Inspecting & Testing Plumbing, Wells, Septic Systems for Defects - Home Buyers and Home Owners
Hot water: how to get more hot water flow, quantity, performance from your water heater Oil tanks, how to find, inspect, test, remove above ground or buried oil tanks. Oil tank piping advice. Septic systems: how to inspect, test, repair, install, maintain septic tanks, septic fields, alternative designs. Tank Types Encyclopedia an encyclopedia of tanks in buildings, water tanks, oil tanks, gas tanks, expansion tanks, cisterns, antique, modern Water wells, water pumps, water tanks, water piping, supply: how to inspect, test, repair Plumbing system inspection, testing, & repairs
We explain how to buy, inspect, install, test, diagnose maintain and repair septic tanks and all other components of all types of septic systems. We discuss how septic systems work, and how to provide septic system care to avoid replacing the septic system unnecessarily. We provide septic cleaning and septic maintenance procedures, septic inspection methods, septic repair guides, and septic system design information.
We give in-depth information about conventional septic tanks, drain fields, septic pipes, and septic waste handling. We describe and explain the need for and how to install alternative septic system designs for problem sites where the need is to save water or where it is difficult to dispose of septic waste. We include tables for septic tanks: pumping frequency, septic tank size, septic tank design, and clearances between septic systems, wells, and other site features and boundaries. This page organizes and links to our detailed septic system inspection, test, repair, and design articles, including our online septic systems book. Septic testing class presentations, septic system photos, septic system design sketches, septic care tables, links to products and consultants are provided. If you do not quickly find here information
Septic Tank & Drainfield Inspection & Maintenance for Home Buyers or Owners
If you own or are buying a home with a septic system, look through the list of articles below.
If you are in a rush read A Home Buyer's Guide to Septic Systems inspection & testing - what to do, step by step to inspect and test a septic system when buying a home and then What is a Septic System? An Engineer's View & Septic System FAQ's.
If you don't know if the building is connected to a septic tank system or to a public sewer, see Septic or Sewer Connection?
If you are having a problem with your septic system, start with the easy articles below but also see our step by step guides at Septic Maintenance and Repair
If you want to avoid septic system backups, see Septic Backup Prevention when you're having a big party or
If your drains are backing up, see Septic Backup Repair
Use links below or at the left of each page to navigate this document or to view other topics at this website
How to inspect & test an abandoned or un-used septic system How to inspect & test a new, un-used septic system
How to Evaluate the Condition of an Abandoned or Un-Used Septic System
Determining the Condition of Never-Used Septic Systems
A septic system that has never been used should not be evaluated by a loading and dye test because chances are the septic tank is empty - the loading test volume of water run into the system is unlikely to even fill the septic tank during the test interval.
If the a septic tank is not full to normal operating level, placing a test volume of water into the septic tank will not move any test water out to the drainfield - the drainfield or absorption system will remain un-tested, and its problems will remain undiscovered.
What to Inspect & Test a Septic System is New & Un-Used
In almost any location where building codes and health codes are enforced, a building permit, a septic system design, soil percolation tests, and approval of the septic system design are required by local health or building department officials.
Contact the building department and health department to ask:
Was a septic design submitted and approved?
Are there drawings, inspection, or test result documents available (obtain copies)?
Was there a final inspection to confirm that the septic system was built as proposed?
Confirm that a septic construction permit was obtained and the system was inspected and approved as built
Identify the septic contractor who installed the system;
Ask for a site tour (offer to pay the contractor for his time) at which the contractor points out (and you mark) the location of septic components (tank, distribution box, drainfield, other site drainage components that may have been installed).
Ask if the septic contractor had to make changes to the original plan. A septic contractor might encounter a buried surprise - rocks, boulders, changes in lot or building plans, that lead to last-minute changes in the septic system layout or in the location of its components.
Ask when the work was completed and whether or not all connections (tank to house, tank to D-box, D-box to drainfield) were completed.
Septic drawing: if an accurate sketch is not already provided, locate and sketch the measurements to and location of all septic system components. See Septic Tank Location. Confirm that the as-built (which may be different than the as approved design) septic system meets all of the setback requirements - distance from well, property lines, streams, etc.
Inspect the septic system site, tank, septic distribution box, septic drainfield:
A septic tank that has never been used should be empty of sewage and water. It is possible that a small amount of water has run into a septic tank during installation if the tank was set during very wet weather, but that's an abnormal circumstance. If there is significant water in the septic tank, more than an inch, the concern is that surface runoff or ground water may be leaking into (and flooding) the septic tank: look for stains at the inlet piping, baffles, covers, tank sides, that might indicate places where water is leaking into the septic tank.
Inspect the septic tank further using the criteria that we list below,
Inspect the site for evidence of settlement, un-wanted surface runoff, or other changes that might have affected the condition of the septic system such as evidence that vehicles have been driven over the drainfield. See Septic Site Inspection Procedure and see Failure Causes - Septic Drainfields.
If the distribution box has tipped, or if there is evidence that surface water is entering the distribution box, these conditions will need to be corrected.
Make certain that the septic tank has save and secure covers. See Septic & Cesspool Safety
If the septic system is reported to be new and never used, the septic tank should be empty. Inspecting the septic tank by finding and opening its service ports will yield important data such as evidence that surface or groundwater are leaking into the septic tank (and flooding the system).
If the septic system is new and never used, the distribution box should show no evidence of flooding or ground water leaking into that part of the system.
What to Inspect & Test If an Un-used Septic System is Old
If a septic system is old, perhaps of un-known age, and it is reported that the system has been un-used for a long time, special inspection and test considerations apply.
Contact the building department and/or health department to ask if there was a septic plan, inspection, approvals for the site, and if drawings are on file. Above we suggest details that might be asked.
Inspect the septic system site, septic tank, and distribution box: find the septic tank (see Septic Tank Location), have the tank opened (be careful not to fall into a tank with an unsafe cover, and never enter a septic tank).
If the septic tank is empty and clean inside it has either been pumped or has never been used. There should be no standing water or debris in the septic tank. A steel, plastic, or concrete septic tank that has never been used will have clean sides with no sewage staining.
While the septic tank is open, look for evidence of places where ground water might be leaking into the tank (DO NOT ENTER THE SEPTIC TANK) - and check the condition of the septic tank inlet and outlet baffles to be sure they are in place.
If the septic tank is not empty inspect the sewage and effluent levels. A septic tank that was in active use but has been unused for a year or even longer should still be nearly full to the point just below its outlet pipe. A septic tank that has been un-used for many years may have lower sewage and effluent level.
But if the septic tank has no effluent, just a dried crust of sewage sludge on its bottom, it is possible that the tank has been damaged and is leaky. Something is probably wrong. A steel septic tank is at risk of having rusted through and lost its liquid volume, so unless the test volume of water is more than tank volume you won’t be testing the drainfield. A concrete septic tank might be cracked and leaky too – but this is less common.
If the septic system's distribution box has tipped, or if there is evidence that surface water is entering the distribution box, these conditions will need to be corrected.
Make certain that the septic tank has save and secure covers. See Septic & Cesspool Safety
Inspect the septic system site for evidence conditions that suggest damage to the drainfield, un-wanted surface water, etc: Site conditions may have changed since the original septic tank or drainfield installation, such as changes in surface runoff, subsidence, nearby construction, vehicle traffic on the drainfield, or even damage to the septic tank, distribution box, or drainfield piping. See Septic Site Inspection Procedure.
Settlement of the septic tank, tank cover, distribution box, or settlement of areas in the drainfield. Any of these may mean that septic components have become tipped or even disconnected. For example, a poor-quality installation of septic drainfield piping with uneven trench excavation, inadequate gravel, un-compacted backfill, may have led to drainfield pipes that have become tipped, disconnected, or blocked with soil. Even a new septic drainfield, just a few months old, might fail under these conditions.
Un-wanted surface runoff that directs water onto the septic tank, distribution box, or drainfield can flood the system and may significantly shorten the life of the drainfield.
Other changes that might have affected the condition of the septic system such as evidence that vehicles have been driven over the drainfield. Driving over the drainfield compacts soil that needs to breathe, and it risks crushed or broken drainfield piping or distribution boxes.
Soil test: You might want to do a soil perc test to see if the soil drains as was claimed when the septic drainfield was built.
Septic drawing: if an accurate sketch is not already provided, locate and sketch the measurements to and location of all septic system components. See Septic Tank Location. Confirm that the as-built septic system meets all of the setback requirements - distance from well, property lines, streams, etc.
Septic loading and dye test for an un-used septic system? If inspection of the septic tank shows that the tank is full or nearly full, then a septic loading and dye test has a chance of disclosing a damaged, blocked, or failed septic drainfield. We find enough septic failures with this procedure (see Dye Tests and also see Dye Amounts, Water Volume) that it's worth performing, but beware: a drainfield that has rested for a few months and that is tested during the dry season might still have a short functional life when it is restored to year round use. Septic loading and dye tests and septic tank inspections should be accompanied by an expert visual inspection of the site as well as a collection of any available historical data.
Septic maintenance history may be available from local septic tank pumping companies. If a few telephone calls can locate a septic pumper who has serviced the property be sure to ask the contractor's opinion of the condition of the septic system.
Also see these Septic System Inspection & Testing articles
Abandoned or New Septic System inspection & testing suggestions
Baffles, Septic Tank septic tank baffles defects and inspection suggestions
Buyer's Guide Home Buyer's Guide to Septic Systems Inspection & Testing - What to Do, Step by Step.
Cesspools Home Buyer's or Owner's Advice
Cesspool Age Estimates help evaluate cesspool condition and need for repair or replacement
Cesspool Safety Warnings include dangers of cave-in and fatality
Clearances & Distances from septic system components to other site features, property boundaries, waterways, etc.
Don't Pump Before Testing Septic Systems: warnings for home buyers about septic tank pumping
Drainfield Inspection Procedure Septic Leach Fields - how to inspect and diagnose septic drainfield failures
Drywells Home Buyer's or Owner's Advice
Dye Amounts, Water Volume: how much septic dye and how much water to use to perform a septic dye test
Dye Tests: how to perform a Septic Loading and Dye Test - the complete procedure for septic loading & dye testing, a septic function test
Failure Causes - Septic Systems Basic Septic Inspection Procedures: for septic tanks, septic drainfields, cesspools, drywells, distribution piping
Failure Causes - Septic Tanks - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
Failure Causes - Septic Drainfields: how to inspect septic leach fields & what causes septic field failure
SEPTIC FAILURE SPOTS - Where septic system trouble is likely to show up regardless of septic dye testing
Life Expectancy of Septic Systems and septic system components
Media Filter Septic Systems types of alternative septic systems using sand, peat, textile, foam cube or other filter media, single pass vs. recirculating media filters, how to identify them.
Pumps Septic pumps, sewage ejector pumps, grinder pumps, effluent pumps, sump pumps, & septic pumping stations compared; pump alarms. Advice.
Septic & Cesspool Safety - septic system, septic tank, & cesspool safety warnings for septic inspectors, septic pumpers, and homeowners.
Septic or Sewer Connection? - how to determine if a building is connected to a septic tank or to a public sewer line
Septic Site Inspection Procedure - Simple Outside Visual Site Inspection Gives Key Information About Septic System Condition
Septic Sludge & Scum Levels in Septic Tanks - Measuring the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks
Septic Tank Inspection Procedure - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
Soil Percolation Tests Perc Tests or Deep Hole Test for Soil Absorption Rate Testing
SPOTTING SEPTIC BREAKOUTS - Spotting Dyed Septic Effluent Breakout Outside - Where Septic Dye is Likely to Show Up During a Septic Dye
Technical Reviewers & References
Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material.
Daniel Friedman - principal author/editor of the InspectAPedia TM Website
Thanks to Rick Kie, Email: AccHomeInsp@stny.rr.com a professional home inspector in Endwell, NY, for helpful discussion of septic testing difficulties at abandoned properties. Mr. Kie can also be reached at 607-221-8724. 09/11/2008. Mr. Kie points out that if a septic system design includes a sand bed with chlorinator, septic test dye is likely to be bleached out and will be difficult to spot
Home Buyer's Detailed Guide to Septic Systems - Buying a Home With a Septic Tank
Advice for buyers of a home with a septic system - what to do What is a septic system - how it works, what goes wrong What to ask about a septic system when buying How to make a visual inspection of the septic system How to test the septic system - dye testing, loading, probing When to pump the septic system - before purchase Where to get information about the septic system
Septic systems include buried septic tanks (sewage tanks) and drainfields - expensive and hidden from view such as in the photo at left. This document provides advice for home buyers who are buying a home with a private septic system: homes using a septic tank and drainfield or similar soil absorption system.
Here we explain how to reduce the risk of a costly surprise by asking questions, visually inspecting the septic system, and by testing the septic system. Chapters 1,2,3 in this file explain what a septic system is and outline step by step septic inspection and testing for home buyers
INTRODUCTION: to buying a home with a septic tank
Home buyers ask us these questions about septic systems:
"What is a Septic Tank?
What is a Leach Field?
How does a septic system work?
What does the existing septic system consist of at my new home?
Do I have a Cesspool or Drywell?
How do I know if the septic system is working properly?
What septic inspections and tests should I have performed when I am buying a home?
How long will a septic system last?
Is septic system maintenance necessary?"
To help buyers obtain the necessary information to address these questions, we have put together this document to guide them in making informed decisions regarding the potential problems and costs associated with a property's septic system.
2-YOU NEED TO KNOW AND DO: How Septic Systems Work. Here is the minimum you need to know and what you need to do (or have done) when buying a property with a septic system
So how does a septic system work? A private onsite septic system means that the waste from your building drains (sinks, showers, toilets) goes into a septic tank which retains the solids and lets the effluent flow into the soils on the property.
Properly designed and installed these systems are functional and sanitary. Private septic systems serve more homes in the U.S. and many other countries than any other waste disposal method. But the components are costly and do not have an indefinite life.
Because of the potential repair/replacement costs involved, and because the system is buried and cannot be exhaustively inspected and tested, you want to do what you can to evaluate the condition of the septic system before you complete the purchase of the property.
Here's what to do: If you are buying a home with a septic tank and drain field, here's what you need to do, as succinctly as possible. Each of these steps is described in more detail below, and in even more detail in linked-to documents. Steps 1 and 2 are essential. Step 3 is usually a good idea. Step 4 depends on the results of steps 1,2,3 but is usually a good idea. Step 5 is not usually done but might be necessary. Step 6 is what you do if you're being really thorough.
Synonyms for "septic system" used by the general public include septic waste system, sewage systems, and water sewage systems, even Roman sewage systems. All of these refer to onsite systems which hold and separate sewage waste from its liquid effluent which is treated further and then disposed-of by any of a variety of means which we will discuss. At this site we also discuss special considerations for handling septic waste such as garbage disposal septic tank waste volume and what to do about it.
Ask About the Septic System - where is it, what's installed, what's the service and repair history
Make a Visual Site Inspection for signs of trouble
Perform a Septic Loading & Dye Test to see if it produces evidence of a failure. Hire a home inspector who knows how to perform and will include this test.
Pump the Septic Tank and inspect for additional clues, depending on what you learned at 1,2,3
Additional Septic System Physical Investigation might be needed
Get Outside Information Sources about Septic Systems if you're being really thorough
Neighboring Septic System Problems - advice for dealing with a neighboring septic system producing odors or seepage
The six home buying steps listed above are explained in detail at 5-HOW TO INSPECT & TEST but first you might want to review the basics about septic systems at 3-SEPTIC SYSTEM COMPONENTS and also 4-WHAT GOES WRONG.
3-SEPTIC SYSTEM COMPONENTS - the Basic Parts of a Conventional Septic Tank and Leachfield
The purpose of a septic system is to retain solid waste in the tank and to dispose of effluent waste water into the ground without contaminating the environment.
To accomplish this a septic system consists of the elements shown in the sketch above. In simplest terms, a septic system consists of a holding tank which retains solid waste and grease from household waste water, and an absorption system or "leach field" which disposes of liquid wastewater or "effluent" which leaves the septic tank for absorption below ground into soils at the property.
Let's just outline these main septic system parts in a little more detail:
The main waste line or "sewer line" connects the home's plumbing to the septic tank.
The septic tank which is often buried just a few feet from the house foundation wall, receives all waste (solid and liquid) and has the main job of retaining solids and grease. Solids settle to the bottom of the tank as sludge. A floating scum and grease layer forms at the top of the tank. Baffles at the tank inlet and outlet reduce the velocity of liquid moving through the tank and prevent solids and floating scum from leaving. Clarified effluent is allowed to flow out of the tank into a soil absorption system. In some states (Connecticut since January 1991) septic tanks now consist of two compartments in order to do a more effective job.
A effluent distribution pipe direct the flow of effluent from the septic tank to the leaching system, often connecting first to one or more distribution boxes which in turn distribute flow of effluent evenly into the leaching system.
A leaching system, or soil absorption system, also called "drainfield", a soakaway system, leachfield, or seepage bed disperses the sewage effluent into the surrounding natural soils. There are many types of leaching systems but the most common is a network of perforated pipes buried in gravel-filled trenches. The specific type utilized on a particular property depends on the soil conditions and the amount of space available.
Galleries or "septic galleys", seepage pits and sand beds have historically been used.
Most distribution piping and leaching systems are "gravity" systems, meaning the flow runs through piping and distribution boxes without the assistance of any mechanical device, such as a pump or siphon, but some homes pump their effluent uphill into a mound system.
Advanced wastewater treatment systems are also available to handle difficult sites.
This chapter describes what goes wrong with septic tanks, drainfields, and other septic system components. Septic backups, failures, breakouts, odors: This document provides advice for home buyers who are buying a home with a private septic system: homes using a septic tank and drainfield or similar soil absorption system.
Chapter 4 in this file outlines what goes wrong with septic systems and their various components. Chapter 5-recommends and describes septic inspection and test methods in more detail, explains how to be sure your septic inspection and septic test are conducted properly, tells you where to get more septic system information about a given property, and warns of unsanitary or dangerous site conditions. Use the links at page left to navigate this document or to go to Other Resources. The Green links at left show where you are in our document & website. Also see The Septic System Information Website. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left.
4-WHAT GOES WRONG with septic systems, tanks, and leaching beds?
4-1 TANK FAILURES - Septic Tank Failures
Do not drive over the septic tank or septic piping.
Unless special provisions have been made such as protection of piping and septic tanks from damage, vehicle-rated septic tank covers, or similar steps, do not drive vehicles over the septic system.
Driving over septic tanks, septic piping, or drainfields risks costly damage to the septic system and may also be dangerous.
The bulldozer in our photo (left) was called to help remove a truck which drove over septic system components leading to a surprise collapse.
Home made or "site built" septic tanks, often using dry-stacked concrete blocks or even stone can collapse, a fatal hazard if someone falls in.
The septic tank shown in the photo at the top of this page had a concrete cover but when the cover was removed we found that the tank was under-sized, built of concrete blocks, and totally impacted with waste, as shown in this open septic tank photo. The system was inadequate, not working, and required replacement.
A proper loading and dye test would probably have detected this failure since the new owners had effluent in their yard within 24 hours of moving into the home. Home made septic tanks which are way too small, such as the 100-gallon home made septic tank shown in the upper left of this photo of a too-small septic tank will simply not be functional for normal use.
Steel septic tank baffles rust off, sending solids into the leach field, shortening its life. A steel tank baffle is visible in the lower left of this photo.
Steel septic tanks rust out and collapse, often sending solids into the leach field and reducing its future life as well. Tank covers themselves can also collapse, especially if made of steel as shown in the same photo as mentioned above.
Other septic tank covers may be made of wood which eventually rots and collapses. Collapsing septic tanks, steel, home made, or any type, are very dangerous. Falling into a tank is likely to be fatal.
Concrete septic tanks such as shown here are pretty durable but they can crack and leak or may have an unsafe cover. The tank shown in this photo is being installed at a new home.
The distribution box has not been placed and is still sitting atop the septic tank. This is a great time to measure and record the exact location of the septic tank and its cleanout access covers.
Concrete tank baffles can deteriorate, crack, break, fall off. Baffles are checked when the septic tank is opened for cleaning.
Fiberglass or plastic septic tanks such as shown here are also quite durable but may be cracked or damaged during installation or if driven-over later.
Septic Tanks which are not pumped often enough can become filled with sludge and scum, becoming totally impacted. Well before this condition is detected, such systems have sent solids into the leach field, shortening its life. See "Septic Tank Pumping Frequency Guide for septic tanks: when, how, what to watch for when pumping or cleaning septic tanks"
More Reading
Diagnosing Clogged Drains: A First Step for Homeowners
Don't Flush these things into a septic system
Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
Septic tank piping failure diagnosis & repair guide
This chapter discusses how to diagnose and repair clogged septic systems or piping. Septic backups, failures, breakouts, odors: This document provides advice for home buyers who are buying a home with a private septic system: homes using a septic tank and drainfield or similar soil absorption system.
Chapter 4 in this file outlines what goes wrong with septic systems and their various components. Chapter 5-recommends and describes septic inspection and test methods in more detail, explains how to be sure your septic inspection and septic test are conducted properly, tells you where to get more septic system information about a given property, and warns of unsanitary or dangerous site conditions. Use the links at page left to navigate this document or to go to Other Resources. The Green links at left show where you are in our document & website. Also see The Septic System Information Website. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left.
4-2 PIPING FAILURES - Septic Piping Failures
Septic Main Drain or Municipal Sewer Piping Failiures
Distribution piping connects the house drain to the septic tank, running between the building and the tank inlet. More distribution piping connects the septic tank outlet to the distribution box and from there to the leach field. Distribution pipes can settle (especially in new construction), break, become blocked or clogged, or become invaded and blocked by tree roots or soils as shown in the first photo above. Clay pipes also break and have a tendency to become blocked by tree roots at their joints as happened here.
Older "orangeburg" pipes which look like black asphalt-soaked cardboard (they are) crush and deteriorate with age. You won't know what kind of piping is installed until it is excavated, but the age of the property may be a clue.
Homes built from the 1970's on, certainly from the 1980's on, use cast iron or more often plastic ABS or PVC piping for these connections, as shown in the second photo above where we were replacing a root and mud-clogged clay sewer line with a new plastic line.
See "Drain Line Replacement diagnosing a clogged drain leads to drain line replacement" for a step by step photo-illustrated guide to diagnosing failed septic piping (or sewer line) and the subsequent drain replacement procedure.
Septic Distribution Boxes
Distribution boxes serve as a connection point to distribute effluent which arrives from the septic tank outlet and is to be sent into two or more individual leach field lines. Distribution boxes ("D-Boxes") can settle or tip.
A damaged or tipped D-box will fail to divert effluent uniformly among the effluent receiving drainfield lines, causing flooding of one leach line. If you see depressions suggesting that there are four leach lines at the property and the end of just one of them is producing wet soil or surface-breakout of effluent, we'd suspect a tipped D-box. (Photo courtesy U.S. EPA)
Septic Drainfield Distribution Piping
Drainfield piping is usually constructed of perforated pipe buried in gravel-filled trenches. It receives effluent from the D-box and allows it to percolate or
seep into the soil around the trench where added filtering and bacterial treatment occur. Like the distribution piping discussed above, individual drainfield pipes can become crushed, shifted, or clogged by tree roots or other debris. More general clogging and failure of the leach field is discussed below. A broken or clogged pipe, once it has been located, may be
much less costly to repair than a complete leach field replacement, so this possibility needs to be considered during diagnosis of a "failed" septic system.
Advice for buyers of a home with a septic system - what to do What is a septic system - how it works, what goes wrong What to ask about a septic system when buying How to make a visual inspection of the septic system How to test the septic system - dye testing, loading, probing When to pump the septic system - before purchase Where to get information about the septic system
This section gives critical advice to people buying a home with a septic tank and drainfield or similar septic systems. This home buyer's guide to septic systems tells what inspection, testing, and maintenance are recommended when buying a home with a private septic system. Learning a little about how septic systems work (described here) and about septic cleaning (removing septic waste), and testing a septic system before buying a new home can help you avoid installing a septic system or replacing the septic system as a big surprise.
Septic systems include buried septic tanks (sewage tanks) and drainfields - expensive and hidden from view such as in the photo at left. This document provides advice for home buyers who are buying a home with a private septic system: homes using a septic tank and drainfield or similar soil absorption system.
Here we explain how to reduce the risk of a costly surprise by asking questions, visually inspecting the septic system, and by testing the septic system. Chapters 1,2,3 in this file explain what a septic system is and outline step by step septic inspection and testing for home buyers.
Other chapters of this guide explain what goes wrong with septic systems, 5-recommends and describes septic inspection and test methods in more detail, explains how to be sure your septic inspection and septic test are conducted properly, tells you where to get more septic system information about a given property, and warns of unsanitary or dangerous site conditions.
If you need to know how to install a septic system, or if you find that you have a sewage pit (cesspool) this website provides articles explaining those topics too. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
2-YOU NEED TO KNOW AND DO: How Septic Systems Work. Here is the minimum you need to know and what you need to do (or have done) when buying a property with a septic system
So how does a septic system work? A private onsite septic system means that the waste from your building drains (sinks, showers, toilets) goes into a septic tank which retains the solids and lets the effluent flow into the soils on the property.
Properly designed and installed these systems are functional and sanitary. Private septic systems serve more homes in the U.S. and many other countries than any other waste disposal method. But the components are costly and do not have an indefinite life.
Because of the potential repair/replacement costs involved, and because the system is buried and cannot be exhaustively inspected and tested, you want to do what you can to evaluate the condition of the septic system before you complete the purchase of the property.
Here's what to do: If you are buying a home with a septic tank and drain field, here's what you need to do, as succinctly as possible. Each of these steps is described in more detail below, and in even more detail in linked-to documents. Steps 1 and 2 are essential. Step 3 is usually a good idea. Step 4 depends on the results of steps 1,2,3 but is usually a good idea. Step 5 is not usually done but might be necessary. Step 6 is what you do if you're being really thorough.
Synonyms for "septic system" used by the general public include septic waste system, sewage systems, and water sewage systems, even Roman sewage systems. All of these refer to onsite systems which hold and separate sewage waste from its liquid effluent which is treated further and then disposed-of by any of a variety of means which we will discuss. At this site we also discuss special considerations for handling septic waste such as garbage disposal septic tank waste volume and what to do about it.
Ask About the Septic System - where is it, what's installed, what's the service and repair history
Make a Visual Site Inspection for signs of trouble
Perform a Septic Loading & Dye Test to see if it produces evidence of a failure. Hire a home inspector who knows how to perform and will include this test.
Pump the Septic Tank and inspect for additional clues, depending on what you learned at 1,2,3
Additional Septic System Physical Investigation might be needed
Get Outside Information Sources about Septic Systems if you're being really thorough
Neighboring Septic System Problems - advice for dealing with a neighboring septic system producing odors or seepage
3-SEPTIC SYSTEM COMPONENTS - the Basic Parts of a Conventional Septic Tank and Leachfield
The purpose of a septic system is to retain solid waste in the tank and to dispose of effluent waste water into the ground without contaminating the environment.
To accomplish this a septic system consists of the elements shown in the sketch above. In simplest terms, a septic system consists of a holding tank which retains solid waste and grease from household waste water, and an absorption system or "leach field" which disposes of liquid wastewater or "effluent" which leaves the septic tank for absorption below ground into soils at the property.
Let's just outline these main septic system parts in a little more detail:
The main waste line or "sewer line" connects the home's plumbing to the septic tank.
The septic tank which is often buried just a few feet from the house foundation wall, receives all waste (solid and liquid) and has the main job of retaining solids and grease. Solids settle to the bottom of the tank as sludge. A floating scum and grease layer forms at the top of the tank. Baffles at the tank inlet and outlet reduce the velocity of liquid moving through the tank and prevent solids and floating scum from leaving. Clarified effluent is allowed to flow out of the tank into a soil absorption system. In some states (Connecticut since January 1991) septic tanks now consist of two compartments in order to do a more effective job.
A effluent distribution pipe direct the flow of effluent from the septic tank to the leaching system, often connecting first to one or more distribution boxes which in turn distribute flow of effluent evenly into the leaching system.
A leaching system, or soil absorption system, also called "drainfield", a soakaway system, leachfield, or seepage bed disperses the sewage effluent into the surrounding natural soils. There are many types of leaching systems but the most common is a network of perforated pipes buried in gravel-filled trenches. The specific type utilized on a particular property depends on the soil conditions and the amount of space available.
Galleries or "septic galleys", seepage pits and sand beds have historically been used.
Most distribution piping and leaching systems are "gravity" systems, meaning the flow runs through piping and distribution boxes without the assistance of any mechanical device, such as a pump or siphon, but some homes pump their effluent uphill into a mound system.
Advanced wastewater treatment systems are also available to handle difficult sites.
Chapter 5-How to Inspect and Test Septic Systems for Home Buyers - Step by Step Details What to do if buying a home with a septic tank Details of How to Inspect & Test Septic Systems When Buying A Home
5-HOW TO INSPECT & TEST When, Where, Why, and How to Inspect and Test a Septic System - for Home Buyers, Step-by-Step
While no septic inspection and test can guarantee 100% that all septic defects have been found, properly conducted, septic inspection and testing procedures can reduce the chances of a dangerous or costly surprise at a property served by an onsite waste disposal system.
When buying a home with a private septic system, septic tank and leachfield, at a minimum you should always should do steps 1-ASK ABOUT THE SYSTEM, followed by 2-VISUAL INSPECTION, and 6-ASK OUTSIDERS yourself.
If you hire an expert to inspect and test the septic system the inspector will also perform step 2-VISUAL INSPECTION and 3-LOADING & DYE TEST. Some home inspectors can provide this service as can independent septic engineers and a few septic contractors. Below we tell you how to get the inspection and testing done properly. Other articles at this website give great detail about how to perform an effective and valid septic system inspection and test.
A septic pumping contractor performs steps 4-PUMP and possibly 5-5. ADDED INVESTIGATIONSL or other measures.
In case you missed it before, steps 1 and 2 are essential. Step 3 is usually a good idea. Step 4 depends on the results of steps 1,2,3 but is usually a good idea. Step 5 is not usually done but might be necessary. Step 6 is what you do if you're being really thorough. Below we discuss each of these steps in more detail.
5-1. ASK ABOUT THE SYSTEM What to Ask the Property Owners About the Septic System
Basic Questions: (An essential step) Ask the seller the following questions. Don't worry if the seller says they don't know the answers. "Not knowing" is also important information. These questions are deliberately a bit vague in order to allow people to tell you whatever they know rather than cutting off or suggesting answers. Convey the answers to these questions to your septic test consultant. >
How old is the property?
Is the property occupied or vacant? If occupied, for how long and by how many occupants? If vacant, for how long?
How long has the seller owned the property?
Where is the septic system? [Tip: if the owner has been at the property for years and does not know where the septic tank is located, they have never pumped it - which looks bad for the leach field. On the other hand, if they know exactly where it is and if it has an easily-opened access cover, you might wonder if it's being pumped unusually often - which could also be a telltale.]
What is installed? [Tip: this means: is it a conventional tank and drain field? Is the tank concrete or steel? How big is the tank? Are there separate drywells or seepage pits? If so the owner may have had a concern with the capacity of the leach field.]
What is the service or repair history of the septic system? [Tip: if the system has received regular pumping that's good. If it has never been pumped, you should be pessimistic about the remaining life of the leach field. If a new tank has been installed but connected to old fields you should be pessimistic about the leach fields. If everything was installed new last year, you may be a lucky buyer.]
When was the tank last pumped? [Warning: if the seller offers to "have the tank pumped for you" ask them not to do so before your inspection. Pumping the tank prevents testing the drain field.]
Other useful but less reliable sources of information about your septic system include:
Ask for any drawings regarding the actual location (an "as-built drawing) of the existing septic system. However while you should ask for drawings and records, you should never completely trust them. For example, a septic system may not have all of its components installed just as they were placed on a drawing. The excavator could have hit bedrock or other obstructions and moved things a bit.
Ask for the records regarding maintenance of the system; Has the septic tank been pumped at a frequency of at least 3 to 5 years?; What pumping contractor was used?; If the system contains a pump. how often has it been maintained?; If major repairs have been made, when and to what extent?
Ask about the past performance of the system. Have any of the symptoms described earlier manifested during the life of the system?
5-2. VISUAL INSPECTION: Make a Visual Site Inspection for Signs of Septic Trouble or Site Limitations
Visual Inspection: (An essential step) Make a visual inspection of the property. Look for wet areas, smelly areas, rocky areas, areas of recent excavation. Also make note of the location of and distance to nearby streams, private wells, ponds, buildings, property lines, and rocky areas, and areas of trees and shrubbery. [Warning: be very alert for evidence of sink holes or subsidence. Do not walk over anything suspicious as you might step into or fall into a collapsing system.]
Once the locations of the septic tank and leaching fields are known, walk over the entire area and observe whether there is any evidence of a sewage overflow condition. Greener grass in the leaching area may not necessarily indicate a system problem. If, however the area is completely saturated and odorous you should be very concerned. It most likely indicates an active failure.
Try to get a sense of how natural conditions are effecting the capacity of the property to disperse water.
Is the sewage disposal area located In a depression which would have a tendency to collect run-off of rain water? Is the lot flat? Is there a water course of wetland (swamp) near the leaching system?
Is the system virtually at the same elevation as nearby wetlands?
Are there steep slopes and/or ledge outcrops which reduce the available area for leaching purposes?
All of the above factors could indicate that the existing system will experience difficulty or, that there may not be much additional area suitable for sewage disposal on the lot if needed in the future.
Step 5-3: Septic Loading and Dye Test Procedure for home buyers What is a septic dye test? When and should it be used? What are the limitations of a septic dye test? Details of How to Inspect & Test Septic Systems When Buying A Home
Septic Loading and Dye Test Procedure for home buyers. This document provides advice for home buyers who are buying a property with a private septic system, that is, a septic tank and a leach field or drainfield or similar soil absorption system. This is 5-3 SEPTIC SYSETM LOADING & DYE TEST, what is a septic dye test, how should it be performed, what are its use and its limitations.
Chapter 5 in answers detail: questions to ask about the septic system, how to perform the visual septic inspection, ordering the loading and septic dye test (the too-obvious results of a dye test at a problem site are in the photo at left), pumping the septic tank, and finding additional information about the septic system. We explain how to be sure your septic inspection and septic test are conducted properly.
5-3. LOADING & DYE TEST How to Perform a Home Buyer's Septic Loading & Dye Test
Pre Purchase Septic Testing (A good idea, essential in some circumstances.) Most home sales are contingent upon a home Inspection. But home inspections do not usually include a test of the existing septic system. Septic Tests are beyond the scope of a professional home inspection but these septic tests are offered as an additional for-fee service by many home inspectors who serve areas where private systems are common. The photo at above left shows septic dye being measured into a toilet to begin a septic loading and dye test.
Hire your own septic test consultant who has experience with and is familiar with septic loading and dye testing standards, a licensed septic inspector (in states which license this specialty such as MA), or a licensed septic system installer, who performs a great deal of work in the particular town. They can give you advice as to the condition of the soils and septic systems In the area and what might be expected (especially pertaining to costs) if/when you find problems with the existing system.
This photo shows a small property bordering on a river. We were told that a "new septic system" was installed but I could not see where a conventional tank and drainfield could possibly fit except below the driveway. Because of the nearly overwhelming temptation at such sites to pipe septic effluent directly into the river, we performed a septic loading and dye test to see if the river would turn red. The river did not quickly turn red but after less than 100 gallons of water had been run into the septic system our red septic dye appeared at the basement entry platform at the edge of the driveway, as shown in the photo used at the top of this page.
A septic loading and dye test is essential if nothing is known about the septic system, if the system is more than 4 years old, if there is already evidence of a problem such as odors, soggy areas, or a history of frequent pumping. Your consultant should tell you his or her level of concern and can tell you if the loading/dye test seems like a good idea or an unnecessary expense. If there is no indication of a septic system problem, and if the system is just a few years old, and if the system has received proper maintenance, the risk level is less and you may elect to skip this test. Warning: even a "new" system may be defective and can fail this test. The photograph shows septic dye being flushed down the toilet to begin the test. Water must be run at fixtures which drain into the septic system to continue this procedure.
Warning:: Unfortunately many of the people performing these tests perform only a perfunctory test such as a low-water volume test (50 gallons is meaningless) or use an insufficient amount of tracer septic dye. Therefore, the conclusions reached from these tests are often misleading. Be sure your test is performed by an expert and that an adequate volume of water is used. We specify no less than 50 gallons per bedroom or 250 gallons, whichever is greater.
Warning: if you hire a separate consultant only to perform the septic inspection and dye test you're at risk of getting a bad deal. It takes time to get enough water into the system to perform a reasonably aggressive test. It's economical to do this test when it is overlapped with other work at the site (like a home inspection). But someone coming to the site just to do the septic test is not going to wait around for 2+ hours for water to run into the system - you're likely to get an inadequate test. If you must use a third party just for this test be sure to review the test parameters and agree on them ahead of time.
Warning: Do not pump the septic tank before the loading and dye test. Depending on its size an empty septic tank could require 2-3 days' worth of water to re-fill the tank. An empty tank means that the "loading water" run into the system during the dye test procedure is simply filling the tank rather than testing the ability of the drain field to absorb effluent.
5-3a WHAT'S A DYE TEST? What is a Septic Dye Test?
This procedure puts a test volume of water into the system to look for evidence of a blocked pipe or for breakout of septic effluent at the yard surface - indications of the need for repair. If you are looking at a completely new home and septic system you might omit this test but don't assume that new systems are immune to failures. Pipes settle and break or systems can be improperly installed. If the tank was pumped immediately before your inspection you should be suspicious, and you might defer the loading and dye test as it may be unable to put enough water into the system to test the drain fields. The dye itself is just a coloring agent to identify water that may appear at the yard surface. It's the test volume of water that's important.
If the septic dye appears on the ground or appears in a brook or catch basin the septic system is in failure. Further investigation will be needed to determine the extent of septic repairs needed, though an informed inspector can often make a reasonable guess about what will be needed: a complete septic field replacement or more limited repairs. The common septic testing dyes used are green or red depending on the environment. We have seen dye breakout in as little as 15-30 minutes in many instances where there was no pre-existing wet spot but where subsequent excavation confirmed that the system was either damaged or in failure. In unusual cases septic dye may appear at nearby waterways as much as five days after the test has been performed.
The first or left-hand photograph shows green septic dye appearing on a leafy yard surface near the drainfield during a septic loading and dye test. The second photo shows red septic dye appearing up through a modest snow cover during a winter test of a septic system using septic dye. Use of florescent dyes permits detection of even very dilute concentrations of dye, but usually the color and sheen of the dye are unmistakable without requiring UV lighting.
5-3b TEST LIMITATIONS Septic Dye Test Limitations
Warning: if dyed effluent or water does not break out on the property surface, this does not necessarily mean the system is functioning or will function properly in the future. There are certainly cases in which effluent does not appear at the surface for some time, possibly up to five days, and there are other defects which predict upcoming expensive repair or replacement of the system but which are not detected by loading the drain field.
National data collected among professional home inspectors between 1985 and 1995 indicated that a significant number of inspectors performing dye tests discovered total failure of the septic system within 20 to 30 minutes of beginning testing. We agree that a dye test is by no means a complete test of a system, that the other measures suggested here are extremely valuable, and that the volume of water used is critical: too little or too much can both be serious mistakes. If a wet area or soggy area is present, dye has been found to appear in the short time indicated. However beware: NYS DEC has found dye appearing in nearby streams as late as five days following a septic dye test in cases where effluent migrates through considerable ground area before entering a stream.
5-3b TEST LIMITATIONS Septic Dye Test Limitations
Warning: if dyed effluent or water does not break out on the property surface, this does not necessarily mean the system is functioning or will function properly in the future. There are certainly cases in which effluent does not appear at the surface for some time, possibly up to five days, and there are other defects which predict upcoming expensive repair or replacement of the system but which are not detected by loading the drain field.
National data collected among professional home inspectors between 1985 and 1995 indicated that a significant number of inspectors performing dye tests discovered total failure of the septic system within 20 to 30 minutes of beginning testing. We agree that a dye test is by no means a complete test of a system, that the other measures suggested here are extremely valuable, and that the volume of water used is critical: too little or too much can both be serious mistakes. If a wet area or soggy area is present, dye has been found to appear in the short time indicated. However beware: NYS DEC has found dye appearing in nearby streams as late as five days following a septic dye test in cases where effluent migrates through considerable ground area before entering a stream.
5-3b TEST LIMITATIONS Septic Dye Test Limitations
Warning: if dyed effluent or water does not break out on the property surface, this does not necessarily mean the system is functioning or will function properly in the future. There are certainly cases in which effluent does not appear at the surface for some time, possibly up to five days, and there are other defects which predict upcoming expensive repair or replacement of the system but which are not detected by loading the drain field.
National data collected among professional home inspectors between 1985 and 1995 indicated that a significant number of inspectors performing dye tests discovered total failure of the septic system within 20 to 30 minutes of beginning testing. We agree that a dye test is by no means a complete test of a system, that the other measures suggested here are extremely valuable, and that the volume of water used is critical: too little or too much can both be serious mistakes. If a wet area or soggy area is present, dye has been found to appear in the short time indicated. However beware: NYS DEC has found dye appearing in nearby streams as late as five days following a septic dye test in cases where effluent migrates through considerable ground area before entering a stream.
5-3c FLOODING TESTS What Are Septic "Flooding Tests"?
Some authors describe an attempt to "flood" the septic system with 1000 gallons of water to attempt to force a sign of system failure to manifest itself. A typical home with a private well and pressure tank should be able to deliver 5 gallons per minute. If this test were performed overlapped with a home inspection (a 2 1/2 to 4 hour procedure) one could obtain this test volume.
Warning this test should not normally be attempted. Placing 1000 gallons of water into a septic system in two hours is likely to exceed its design parameters, and in the case of certain systems, it could actually damage the system. While all inspections and tests should aggressively seek to protect the interests of the parties involved by being thorough, a test which exceeds system design parameters would be improper.
5-3d PROBE TESTS of Septic Fields & Locating Septic Components
Probing is a procedure whereby the Inspector attempts to locate the "key" elements of the system (septic tanks and leach fields) and determine if they are experiencing hydraulic distress (meaning the septic tank and fields are flooded).
If a probe in a leach field produces a hole which fills rapidly with water this test indeed indicates a problem with the system. But if a probe does not produce this condition, the test has been unreliable since it may be during a time of dry soils or a day when very little water was used by the homeowner or the home in fact may have been vacant.
This test, if performed, must be done by an expert, with caution, and is inconclusive if it does not detect a problem.
This test, if performed, must be done by an expert, with caution, and is inconclusive if it does not detect a problem.
The photo here is not really a probe test, rather our septic pumping contractor is exploring the condition of the septic tank after it has already been located.
WARNING: probing can damage buried equipment such as fiberglass septic tanks or tank covers or plastic septic drain lines. Further, there is little assurance that the probing is done in the area where a problem is present.
Chapter 5-How to Inspect and Test Septic Systems for Home Buyers - Step 4 - Pump the Septic Tank
5-4. PUMP THE SEPTIC TANK When & How to Pump the Septic Tank When Buying a Home
After performing the septic loading and dye test and obtaining whatever historical maintenance and repair information you can obtain from the prior owner, you may want a septic contractor to located, open, pump, and inspect the septic tank
The decision to include this next and more invasive step depends on what you have already learned about the age, history, and probable condition of the system. The pumping decision should be advised by the visual inspection, site history, and loading/dye test results.
Warning: [Repeated from the Dye Test discussion] Do not pump the septic tank before the loading and dye test. Depending on its size an empty septic tank could require 2-3 days' worth of water to re-fill the tank. An empty tank means that the "loading water" run into the system during the dye test procedure is simply filling the tank rather than testing the ability of the drain field to absorb effluent.
Pumping a septic tank prior to purchasing a home may or may not be necessary, depending on the age and service history of the system and the results of the visual inspection and loading and dye test. For example, if a tank is less than two years old or was pumped in the last year, and if there are no other signs of septic problems at the site, we might defer the pumpout. In this case we would strongly recommend calling the pumper to ask about the condition of the system at the time they last cleaned it.
The decision to include this next and more invasive step depends on what you have already learned about the age, history, and probable condition of the system. The pumping decision should be advised by the visual inspection, site history, and loading/dye test results.
Warning: [Repeated from the Dye Test discussion] Do not pump the septic tank before the loading and dye test. Depending on its size an empty septic tank could require 2-3 days' worth of water to re-fill the tank. An empty tank means that the "loading water" run into the system during the dye test procedure is simply filling the tank rather than testing the ability of the drain field to absorb effluent.
Pumping a septic tank prior to purchasing a home may or may not be necessary, depending on the age and service history of the system and the results of the visual inspection and loading and dye test. For example, if a tank is less than two years old or was pumped in the last year, and if there are no other signs of septic problems at the site, we might defer the pumpout. In this case we would strongly recommend calling the pumper to ask about the condition of the system at the time they last cleaned it.
Even if there are no signs of trouble from the inspection and dye test, if nothing is known about the system history, or if it is known that the system has not been opened and pumped in 3 years or longer, this step is strongly advised. If the septic tank has been pumped quite recently, you should call the pumping contractor to ask if, at the time of pumping, the contractor observed any indications of system problems or upcoming system repairs.
5-5. ADDED INVESTIGATIONS Additional Septic System Physical Investigation Measures
Additional steps which are not normally done but which may be performed if there is evidence of system damage or failure are listed next. These steps would ordinarily be performed by a septic contractor who installs or repairs septic systems. Some septic pumping companies also perform septic repairs and field investigations. A septic engineer may be needed if you are expanding a system or if you require design to repair a system on a difficult site.
Find and Open the Distribution Box which connects the pipe from the tank to the network of drainfield lines.
Excavate suspicious areas such as wet areas at in the leach field, subsidence areas.
Perform soil percolation tests or "Perc tests" to evaluate the ability of the soils to absorb effluent. This involves digging a hole, pouring in water, and measuring the time for a given volume of water to be absorbed into a given square foot area of soil.
Soil & Site Research to include determination of the soil quality, the depth of the seasonal high water table in the ground below the leach area, etc. - this work may be needed if a system is to be replaced or relocated, especially at a difficult site.
5-6. ASK OUTSIDERS Other Information Sources About Septic Systems
Talk to neighbors about the general performance of septic systems In the area and specifically the system on the property you're Interested In. However, this is suggested only for those comfortable approaching this subject with strangers and with the realization that the information gathered may not be totally factual for various reasons (devaluation of their own property; not wanting to spoil the sale of a friendly neighbor, etc.)
Soil Maps: Use of Soil Conservation Service County Soil Maps (through the town sanitarian), try to identify the type of soil most likely present on the site in order to predict the feasibility of future repairs to the existing leaching system.
Water Meter Readings: Obtain water meter readings (if the home is serviced by a municipal water supply) to determine what the present occupants of the home are utilizing. Then compare those results with what your family is presently using. If your family Is using significantly more water than the former occupants you may be asking for trouble if the sewage system is undersized by today's standards.
Tank Pumper Records: Additional useful information which may be available from the service company who has pumped the tank recently includes the following:
Type of tank material - old steel tank may be at or end useful life
Tank size - along with usage determines appropriate pumping frequency and system capacity
Evidence of damage to tank components - broken baffles mean the leach fields are probably ruined
Evidence of backflow into the tank during start of pumping - indicates flooded leach field, probably failed
High sludge level and/or excessive floating scum level - indicate high risk of having pushed solids out into the leach field, destroying it
If the system has not been cleaned in several years and if the seller will permit, have the tank pumped to obtain this additional information. Typical pumpout fees are around $100. if excavation is not necessary. If the tank location is unknown extra costs will be involved to locate and excavate it - steps to which a seller is likely to object.
Health Department: Go to Town Health Department to Review the Property's Septic System Information File.
Ask the town sanitarian to review the file with you. Is there enough information in it for him/her to give you an opinion on how the existing system and/or lot meets present health code requirements?
Ask for the records regarding maintenance of the system; Has the septic tank been pumped at a frequency of at least 3 to 5 years? What pumping contractor was used? If the system contains a pump, how often has it been maintained?; If major repairs have been made, when and to what extent?
Your goal is to, confirm and supplement information received from the property owner.
Obtain guidelines concerning the proper maintenance of a subsurface sewage disposal system.
If you are contemplating an addition to the home or plan on renovating an unfinished basement discuss the possibilities with the sanitarian and determine the procedures you would have to follow to accomplish your plans. In wm cases it will not be possible to "enlarge" an existing home.
Ask about the general neighborhood, the frequency of repairs, ability to install proper size repair systems, average life of systems in the area, etc.
Technical Reviewers & References
Water Tanks, Water Testing Guidelines for Home Owners and Home Buyers
Diagnosis & repair guide for water wells, well pumps, & water tanks
Water piping, water supply diagnosis & repair
Water testing: how to inspect, test, repair problems with drinking water
Drinking Water Tests, Water Contamination Limits, Drinking Water Testing Procedures
Types of Tanks Found in Buildings, Water Tanks, Tank Repairs, When to Replace a Tank
Encyclopedia of types of tanks and vessels found in buildings, what they look like, what they do
Types of home water storage tanks and when to replace them.
Water storage tanks, cisterns, rooftop tanks, open tanks, water pressure tanks, steel tanks, range boilers, indirect-fired water heaters
Expansion tanks in attics & basements, oil storage tanks, other tanks in attics, basements, etc.
Well pump & water tank diagnosis & repair procedures
This article describes water tanks and other kinds of tanks found in buildings, captive air and traditional water storage tanks or water pressure tanks, and we provide advice about what to do when things go wrong, such as finding air and water leaks or deciding to replace a water tank. Readers of this document should also see
Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost and see
Wells, Cisterns, & Springs for a discussion of types of drinking water sources and what goes wrong with water supplies. If you're looking for information on types of septic tanks see our
Septic System Design which includes articles about various types of septic tanks, steel, concrete, plastic, etc. The illustration at page top is courtesy of Carson Dunlop, Inc. in Toronto.
© 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Various types of tanks uses in and around buildings are identified and explained below, including water pressure tanks, water storage tanks, range boilers for hot water, indirect fired hot water tanks, expansion tanks in attics, basements, and on heating boilers, oil storage tanks, rooftop tanks, cisterns, water pressure booster systems. We also discuss when to replace water tanks.
Types of residential water tanks
CAPTIVE AIR TANKS bladder-type water tanks for Building Water Pressure Regulation
Newer "captive air" tanks use a rubber bladder to keep water and air separate. This prevents the air charge from being absorbed into the water, so you should never need to add air to those systems. At WATER TANKS HOW THEY WORK we provide details of how water pressure tanks work.
Loss of air in "captive air" bladder type water pressure or water storage tanks
If a "captive air" or internal "bladder" (usually rubber) type tank is installed, and if the pump is short-cycling on and off, you should turn off the pump and call a plumber.
We would suspect that the bladder has ruptured, or that the tank itself has developed a leak. We explain waterlogged water tanks and water pump short cycling in detail at WATER TANK REPAIRS where we also explain how to correct these conditions.
Regardless, short cycling could damage the pump or pump controls. These tanks are made of steel or fiberglass, and typically have an air schrader valve at the top of the tank. The air valve is used for adjustment of the air pressure in the tank at the time of initial installation. Normally you never need to add air to these tanks after initial installation. Sketch courtesy of Carson Dunlop.
The newer type "captive air" tanks, one which use an internal bladder to contain the water separately from the air charge, can also fail. The bladder can rupture as we discussed above - you need a new tank. The tank itself can develop an air leak - you need a new tank. But these failures occur less often than with the older single chamber steel water pressure tank, largely because the tank bladder holding the water supply protects the tank interior from corrosion.
If the captive air water pressure tank bladder is ruptured, the air charge in the tank becomes lost over time and the tank acts like a water-logged steel tank discussed below.
If the captive air water pressure tank bladder is collapsed,, defective, jammed, and stuck on itself it may not accept much volume of water, also leading to a short draw-down cycle before the pump has to turn on again. This is an unusual case but has been reported
Steel Water Storage/Pressure Tanks
The water storage tank in the photographs above is leaking, having rusted through from inside the tank. (This tank is less needed for storage than to smooth or regulate the water pressure in the building as the pump cycles on and off) Leaks like the ones in these photos can also leak the air charge out of the upper portion of the tank when the in-tank water level is below the leak point. So you might trace a water pump short cycling problem to an air loss in the tank to a leak in the tank itself
How to detect a waterlogged water tank
If a steel water tank has lost its air charge, or most of it, the condensate line on the tank will be high, near the top few inches of the tank side (unless you live in an arid climate where there is never condensation on the water tank anyway.).
In this condition the steel tank is called a waterlogged water pressure tank. Such tanks will also be heavy and won't be so easily rocked or moved - a simple test I make to see if the tank is empty or full of water. (Don't move the tank so much that you cause a water piping leak!
When to add air to a water tank
The discussion on how to add air to a water pressure tank at this website beginning at HOW TO ADD AIR applies principally to older steel water tanks that don't use an internal bladder to keep water and air separate.
In these simpler single-internal chamber steel tanks the air charge is lost either by absorption into the water as it passes through the tank during use, or it may be lost by leaks at the tank or nearby plumbing fittings.
Automatic ways to add air to a water tank
Some old-style bladderless steel water pressure tanks are equipped with an air volume control device which is intended to put makeup air into the tank as air is lost or absorbed. I discuss these further at 1: AIR VOLUME CONTROLS but suffice it to say these often stop working. But if you see one on your water tank you know this is a non-bladder type older style water pressure tank.
Range Boilers for Domestic Hot Water Systems
Range boilers are vertical or horizontal hot water systems whose water is heated by circulating the water from within a water storage tank (the range boiler) through a heat exchanger which is inside or connected to the exterior of a heating boiler. The water in the hot water tank range boiler is heated by circulating its water through the heat exchanger which itself is heated by the water inside or from the heating boiler.
The sketch illustrates how a very early type of coal-fired water heater range boiler worked. As homeowners shifted fuels from coal to oil or gas and installed central heating boilers, often the range boiler water heater was adapted to work with these systems as well, as you can see in the photograph.
As with the indirect-fired boiler described next, range boiler water heating tanks are usually located close to the heating boiler and will have both cold and hot water lines leaving the tank to supply the building with domestic hot water and a loop of piping that runs between the bottom of the hot water tank and a nearby heating boiler. Follow the pipes to see which pipes are performing which function. Our photo shows a silver steel range boiler hiding back in the corner behind the newer (though pretty old) gas fired water heater. (Notice also the efflorescence on the masonry block foundation, where the downspout has been spilling by the house foundation?)
See WATER HEATERS for details about residential hot water systems.
Indirect-Fired Domestic Hot Water Tanks
Indirect fired water heaters: In some other buildings domestic hot water is produced by cycling hot water from a hydronic or steam boiler through a loop inside of a steel tank. The water in the tank is heated by the water in the coil.
Modern systems using this approach use the term indirect-fired water heater and such systems are sold by various companies such as the SuperStorTM unit shown here as the white tank to the right of the heating boiler.
You may also notice the WellXTrolTM blue water tank off to the left of the boiler as well as in the left foreground covered partly by a cardboard box we have a white-yellow fiberglass close to the thin blue vertical water softener - water treatment equipment in the same photo. And just to be complete, the little tank over the boiler next to our service technician is the expansion tank for this heating boiler.
Indirect fired water heater tanks for domestic hot water, such as the SuperStorTM are usually located close to the heating boiler and will have both cold and hot water lines leaving the tank to supply the building with domestic hot water and a loop of piping that runs between the [usually the] bottom of the tank and a nearby heating boiler. Follow the pipes to see which pipes are performing which function.
The difference between a range boiler and an indirect fired water heater is in the details. The heat exchanger that heats water in the range boiler is in or at the heating boiler. The water in an indirect fired water heater such as the SuperStorTM unit is heated by a finned copper coil located inside the hot water tank. The internal coil is in turn heated by circulating water inside the coil to and from the heating boiler. The range boiler is an old concept in use for about 100 years. Indirect fired water heaters are a modern system and are in current sales and use.
Attic Expansion Tanks for Heating Boilers
Attic expansion tanks and pressure relief systems for boilers: Don't confuse an old heating system attic-mounted expansion tank like the one shown here for a water tank storage tank. The heating system expansion tank will be connected to the heating system radiators or basement boiler and may have a simple overflow pipe to permit excessive water (or system pressure) to spill outside.
This attic expansion tank may have been connected to a drain that spilled outside of the building in case the tank became over-full. You can also see a sight glass on the front of this tank, allowing the service person to see its conation.
Heating systems with this equipment installed may not have a modern pressure and temperature relief valve. Certainly in the original design the tank was put in the attic so that heating water could rise to the upper floors of the building by pressure within the heating system, but if pressure got dangerously high, heating boiler water would just spill up into the attic and thence to outside. Systems which rely on a remote attic-mounted expansion tank are less safe since than a boiler that has a pressure and temperature relief valve mounted right on or at the boiler. It's an easy fix, usually, to just add a relief valve on or at the boiler.
Basement Expansion Tanks for Heating Boilers
Our client is pointing to a do-it-yourself insulating job on a water heater. But that reddish-brown horizontal tank over his head is an expansion tank for the hydronic heating boiler in this building. This is not a water storage tank, it's not a range boiler, it's an expansion tank.
There will usually be just one pipe leading to this tank, coming from the boiler or perhaps a nearby heating water pipe to the tank to permit it to accept the expansion of water in the heating system (or expanding air entrained in the heating system's water) as the boiler gets hot. Otherwise the boiler relief valve might open and spill every time the boiler went through a heating cycle. You'll also find a drain on the bottom of this boiler, used by the heating service technician.
Guide to Hot Water Heater Selection, Inspection, Diagnosis, & Repair
Water heaters: how to inspect, test, adjust, repair, and choose among types of hot water heaters Guide to inspecting gas fired hot water heaters Guide to inspecting oil fired hot water heaters Guide to inspection of electric water heaters Guide to tankless coils, indirect fired water heaters, range boilers No Hot water? how to get more hot water flow, quantity, performance from your water heater
Inspection, Diagnostic, & Repair Guide to Residential Hot Water Heaters
While an electric, gas-fired, or oil-fired water heaters, along with tankless coils on heating boilers are among the most common methods for producing domestic or residential hot water for washing and bathing, there are plenty of other ways that people obtain hot water.
All hot water supply systems use some energy source (electricity, oil, gas, solar energy) to heat either a reservoir of hot water stored in a hot water tank, or to heat water as it is used (such as tankless coils and Thermar type heaters.)
Guide to Alternative Hot Water Sources
Description of Types of Alternative Hot Water Heating Methods: electric, gas, high efficiency gas, oil, high efficiency oil, solar, tankless coils, instantaneous water heaters, point of use water heaters
How to use multiple water heaters in series for more hot water and lower hot water cost
Guide to range boilers & guide to side arm coil water heaters
Solar water heater suggestions to save on water heating cost
A Comparison of Alternative Hot Water Heaters & Sources
The following articles discuss alternative ways to produce domestic hot water for washing and bathing.
High Efficiency Water Heaters such as direct-vent gas-fired water heaters
Indirect-fired Water Heaters which use a separate heating boiler to produce a larger quantity of hot water
Instantaneous Water Heaters point of use systems that have little or no standby energy losses
Multiple water heaters in parallel to increase total hot water quantity
Multiple water heaters in series to stage hot water heating for varying levels of demand
Range Boiler Water Heaters an older form of indirect-fired hot water heating used with separate heating boilers
Side Arm Coil Water Heaters similar to instantaneous and tankless coil water heaters, often used with range boilers
Solar Water Heaters using solar collectors, an indoor water tank, pump and controls, using minimal "on-grid" energy
Tankless Coil Hot Water Increase a heat exchanging coil immersed inside of a heating boiler heats provides (somewhat limited) hot water. various tricks can significantly improve the safety and water quantity available
The characteristics of various water heaters such as life expectancy, cost, safety, and capacity are discussed at WATER HEATER PROPERTIES
Ways to improve total hot water quantity, pressure, temperature and flow are discussed beginning at HOT WATER IMPROVEMENTS and continuing at HOT WATER QUANTITY IMPROVEMENT.
Multiple Hot Water Sources? How to Use Separate Oil, Gas, or Electric, Solar, Wind, or Combination-fuel Water Heaters for More Hot Water
Separate water heaters can provide more hot water than a tankless coil in most cases and choices among water heater types by fuel, size, recovery rate, etc. can make a big difference in the hot water quantity, pressure, flow, and cost at a building. Here we discuss some alternative water heating methods.
Use Instantaneous Water Heaters for Increased Hot Water Supply
Installing an instantaneous water heaters are usually installed as a 'point-of-use' hot water system. You can see the basic appearance of a point-of-use instantaneous water heater in the sketch at left, provided courtesy of Carson Dunlop.
For example an instantaneous water heater, electric or gas fired, may be installed at a single kitchen or bathroom.
In the U.S. and Canada, this is an approach to providing hot water that is usually applied where the total hot water delivery rate needed is modest or where only a limited number of fixtures need to be supplied with hot water.
How to connect multiple water heaters in parallel to increase total hot water quantity
Where hot water volume requirements are high, in addition to installing a single larger-capacity water heater, one can install a several water heaters connected in parallel. You can see this design in our sketch at left, provided courtesy of Carson Dunlop.
Parallel water heaters means that all of them are "on" and heating water at the same time, providing a very large quantity of hot water to the building.
We see this installation most often when building occupants find that they do not have enough hot water but their present water heater is in good condition.
Rather than scrapping a perfectly good water heater to install a single larger unit, a second water heater is simply added, installed in parallel to the first one.
How to increase hot water quantity using multiple water heaters in series for lower hot water cost
Some buildings use water heaters installed in series to handle variations in hot water demand more economically. Unlike the illustration of parallel water heaters shown above, water heaters connected in series means that incoming cold water flows first into heater #1, then out of heater #1 into heater #2, then out of heater #2 into the building hot water supply piping (or into additional water heaters if more than two are used.)
A synonym for water heaters connected in series is a cascaded water heater design. Cascaded or in-series water heaters is an economical way to handle large variations in hot water demand in a building.
When the anticipated hot water demand is low, only water heater #2 may be running.
When the anticipated hot water demand is high, water heater #1 is turned on as well, doubling the volume of hot water available (if the heaters are of the same capacity in gallons or liters).
Water heater controls can be adjusted so that the "upstream" water heater, (water heater #1 in our example), is left turned off or perhaps set to a very low temperature. In either of these cases, the upstream water heater or tank functions as a "booster water warmer" reducing the energy use by water heater #2 by pre-warming water entering the active heater#2.
See Extra Tanks to Increase Hot Water for more discussion of extra tanks to provide more hot water.
Use of a Side Arm Coil to Make Hot Water from a Heating Boiler
A side arm coil is quite similar to an in-boiler tankless coil except that it is located outside of the the heating boiler itself.
We found this system common on older home heating systems such as those using a GE down-fire heating boiler or other boilers whose original design did not include an opening and fittings to mount the tankless coil right into the boiler itself.
Also see WATER SOFTENERS - how to install and adjust a water softener to avoid hot water piping or tankless coil clogging due to hard water and minerals - since a side arm coil can also become clogged by the minerals in hard water