Signs of Septic System Failure
Step by Step Septic Problem or Failure Diagnosis
SEPTIC FAILURE CRITERIA - CONTENTS: How Does Each Septic System Component Fail? What to Look For During a Septic Inspection - Step by Step Diagnosis of Septic System Failures, clogged drains, odors, sewer backup, wet areas in the yard, and slow drains
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This septic system inspection article describes detailed "how to" steps instructing the septic inspection investigator in
how to inspect specific septic components for signs of failure.
We describe the criteria for saying a septic system has failed,
and we take you step by step through the onsite waste disposal system, from the building to tank to absorption system, with
suggestions for examining the condition of each component so that a proper diagnosis of the cause of septic failure and a
specification of the appropriate repair can be made.
In the photo at the top of this page, a wet spot appeared in the previously "perfect" yard of this
older home within twenty-four hours of the new family moving-in. The buyers had obtained a "septic inspection" but it was improperly
performed and missed the chance to discover before purchase that the septic system was in total failure.
SYSTEM FAILURE CRITERIA - Septic System Failure Causes: What Constitutes a "Failed" Septic System?
Before digging up your septic tank or calling a septic pumper, if you think the septic system is failed because of
drain blockage or drains backing up into the building, you should to see Diagnosing Clogged Drains: Is it a blocked drain or the septic system? - A First Step for Homeowners. If you link to that text, please return here using your browser's "BACK" button.
Massachusetts Title 5 Septic Law lists specific failure criteria and serves as
a good model for septic inspections anywhere. (The photograph shows the septic baffles in a concrete septic tank. While at the time of inspection the sewage was not flowing over the baffles, sewage debris atop the concrete baffle shows that at some point that problem had occurred. Further diagnosis was in order.
Metal septic tanks (municipality dependent; note that in special site conditions small metal tanks may be the "only" solution and
may be approved by local officials. An owner/buyer must be informed of the implications of such installations.) See Septic Tank Types for more details.
Soil Absorption System (or cesspool, etc) is at a depth exposing it to the maximum groundwater level. See Septic System Design for more details.
Depressions or low areas over the septic tank, septic drainfield depressions: a depression in the septic tank area or a septic field depression may or may not indicate trouble with the septic system. It is normal for backfill over septic tanks or drainfield lines to settle and leave a depression or "low area" in the soil.
But if the septic tank or fields have not been dug-up, or otherwise disturbed and if you see a new depression or area of settlement it should be marked-off, access to that area should be prevented, and it should be investigated by a professional - possible collapse of a septic tank, distribution box, or other buried septic components can be very dangerous or even fatal. See Septic & Cesspool Safety for details.
HOUSE TO TANK - Septic Piping Failures Between Building Drains and the Septic Tank
Outside, waste piping conducts sewage (black water and gray water) from the building to the treatment tank or "septic tank,"
and from the treatment tank to the distribution box. Our photo shows a new waste line carrying sewage down from the home to the
septic tank in lower yard. The previous waste line had been broken when driven over by a heavy lawnmower.
Septic drain lines between the house and the septic tank should be of solid, non-perforated material and need to be
protected from mechanical damage (such as by vehicles). Piping extending from the distribution box into drain fields
is normally perforated, though solid lines might be used if effluent is being processed by more specialized devices such
as seepage pits, galleys, or a sand-bed system.
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.
"orangeburg" pipes which look like black asphalt-soaked cardboard (they are) crush and deteriorate with age. Clay pipes
also break and have a tendency to become blocked by tree roots at their joints. 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.
This line may become blocked by waste, damaged by collapse of a section, or invaded by roots.
Detection of these conditions is fairly easy by routing a snake or power snake from the building drain to the septic tank.
An experienced power snake operator can often tell by "feel" that a drain line is collapsed, partially collapsed, or invaded
by roots. While you may make a temporary "repair" of such a condition by drain-cleaning, if the line is broken or
root-invaded, you should expect to have to excavate and replace it soon.
SEPTIC TANK FAILURES - How Different Types of Septic Tanks Fail
Additives: Use of septic tank or drain field additives which claim to extend system life can generate so much activity in the tank that solids are held in suspension and forced into the soil absorption system! Do not add any treatments, chemicals, yeast, or other treats to a septic system. In general these treatments don't work, may ruin the system, and
are illegal in many localities. There is no magic bullet to repair a bad SAS.
Concrete tanks are pretty durable but they can crack and leak or may have an unsafe cover.
Concrete tank baffles can deteriorate, crack, break, fall off.
Concrete tank lids: can be damaged by vehicle traffic; heavy duty covers are available.
Concrete tanks can crack or sections may separate causing leaks with the same effects as just stated
Concrete tank baffles: may erode from chemicals, detergents, poor concrete mix, water flowing over top of baffles, or may be broken by improper pumping procedures
Diapers, Toys, Garbage which find their way into building toilets and drains risk clogging the drain piping,
distribution piping, or the septic tank baffles. Keep diapers, tampons, sanitary napkins, kids toys, household chemicals, and the like
out of your building drains and toilets. See WHAT CAN GO INTO TOILETS & DRAINS?
Driving over the septic tank, septic piping, or drainfield are likely to crush a pipe, collapse a tank, or ruin a drainfield. Only if special installation steps have been taken can a septic pipe or tank be located below a driveway or parking area and never can a septic drainfield work in such a location.
Garbage disposers also increase the solid waste load on septic tanks and may
require that the tank be pumped more often.
Home made septic tanks:
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 tank shown in the photo here 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 the open septic tank photo.
The septic system was inadequate, not working, and required replacement.
Incidentally, this was the septic system "serving" the property with the nice green lawn in the photo at the very top of this page.
property seller was an elderly, single occupant who used no water and never did laundry in her home.
The new owners had effluent in their yard within 24 hours of
moving into the home.
The buyer's inspector performed an inadequate septic inspection and test.
A proper loading and dye test would probably have detected this failure.
Leaks: Septic tank leaks: a septic tank should be water tight. If ground or surface water leak into the tank the result is often a flooded and failed drainfield; if sewage effluent leak out of the septic tank the result is the discharge of inadequately treated effluent into the soils and in the case of a very leaky septic tank, the result may also be a too-rapid loss of effluent in the septic tank resulting in too rapid build-up of solids and total system clogging and failure.
Pumping: 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.
Rusting steel tank covers can cause death! Rusted covers can collapse. 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 tank covers may be made of wood which eventually rots and collapses.
Collapsing septic tanks are very dangerous. Falling into a tank is likely to be fatal.
We have reports of
children and adults who have died from this hazard (December 1997, California).
In 2000 we consulted in a fatality involving an adult falling into a cesspool.
At a building inspection I myself stepped through a hidden, rusted-through steel septic tank cover.
Falling into a septic tank, drywell, or cesspool is quickly fatal, either from being buried by falling soils and debris, or by asphyxiation. Septic gases are highly toxic and can kill in just minutes
of exposure. Even leaning over an empty (just pumped) tank has led to collapse and fatality of a septic pumper.
Steel septic tank baffles rust off, as you see in the lower left of the above photo which also
depicts a very dangerous rusted-out steel septic tank cover.
Even if the
cover is intact a rusted or lost septic tank baffle sends solids and grease into the leach field, shortening its life.
A steel septic tank baffle is visible in the lower left of this photograph.
Steel tank bottoms rust out permitting effluent to leak into soils around the tank, possibly giving a large void in tank at time of testing,
thus subverting a loading or dye test
SEPTIC TANK TO DISTRIBUTION BOX - How to Find The Septic Blockage
The same failures can occur on the effluent distribution pipe line from the septic tank outlet in to the distribution
box as we described earlier on piping from house to the septic tank.
Pipes can settle (especially in new construction), break, become blocked or clogged, or become invaded and blocked by tree roots or soils.
How to Determine Where a Septic Blockage Is Located
How would we distinguish among blockages at different points in these distribution lines?
Blocked pipe between house and tank: discover by snaking the line from house to tank or by observing a backup
in the house and, on opening the septic tank access cover, observe poor or no flow into the tank when water is
running in the building drains.
Blocked pipe between tank and D-box: discover by opening the tank and seeing that it is not draining out when
water is being run into it from the building drains, and by opening the D-box to observe poor flow or flow into
the D-Box when the tank is backing up.
Blocked leach field lines: discover by excavating at sample points along individual leach lines, often
by opening up the line at its lower end. If no effluent is present at the lower end of a leach field line
and if effluent is entering that line at the D-Box the line is collapsed or blocked along its passage.
Failed leach field: effluent is confirmed as flowing freely from building drains to tank, tank to
D-Box, and D-Box attempting to flow into the leach lines - perhaps both backing up in the D-Box (see flood lines
above the D-Box outlets) and also flowing out at the excavated ends of the leach lines.
D-BOX FAILURES - What Goes Wrong at the Septic System Distribution Box
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.
("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.
Opening the D-box can also show whether or not
effluent is being directed uniformly into each of the leach lines. A tipped D-box can overload one line and cause
early failure of the absorption system.
If this is happening, flow adjustment end-caps (eccentric holes) can be
installed in the distribution box on the inlet end of each of the drain lines, permitting adjustment of
effluent delivery into each line, perhaps relieving the problem line and redistributing effluent into the others.
DRAIN FIELD PIPING - Diagnosing Leach Field Failures
In a conventional "drain field" of perforated pipes buried in gravel-filled trenches,
a drain line may be invaded by tree roots. This is why experts advise keeping tree and shrub plantings away from drain
Vehicle traffic can also collapse this or any outdoor waste piping, which is why experts advise against ever
driving over a drainfield or over any other septic system components. See DRIVING or PARKING OVER SEPTIC
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 failures of the leach field are 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.
Building on the leach field: A leach field can be destroyed by other site "improvements" such as this attempt to install a swimming pool
atop the leaching area in the photo shown at left. This mistaken installation involved multiple errors:
placing a pool atop the leaching area which prevents
proper oxygenation and evaporation, driving over the leach field which risks damaging buried pipes and compacting the soil, and excavating to
remove a portion of the absorption system soil to put in the swimming pool.
The gray water you see next to the swimming pool in
this larger photo was effluent from the failed septic fields.
Compacted soils: driving over the leach field in any vehicle larger than a child's bicycle is a bad idea. Heavy vehicles
may actually crush buried leach field lines, or they may compress the soils around the leach field, either of which leads to failure. Driving
on or parking on leach fields will destroy them.
Paving over the leach field: a leach field cannot function properly if it is paved-over. Some folks may try this as a way
to permit parking over the absorption system. But paving prevents both evaporation of effluent (a portion of the effluent disposal
method) and it prevents oxygen from reaching the soil, thus inhibiting proper bacterial action needed to treat the effluent.
Clogged soils: Soil absorption systems stop absorbing. Eventually the soils around the leaching bed trenches become clogged and
stop passing effluent. Sending grease and floating solids into the leach field hastens this failure.
The biomat which forms below the leaching beds may also become too solid and impacted, stopping soil absorption.
In this leach field photo effluent was appearing in the light colored
area where the homeowner had begun some exploratory digging in a soggy spot only to see her hole fill up rapidly with effluent.
In the building drains become sluggish, stop, or back up into the building (unsanitary), or effluent may appear
on the property surface when the absorption system can no longer function or where a pipe has become damaged.
Lockwood, in "An Engineer's View of Septic Systems" listed these causes of absorption field failure:
If the liquid effluent cannot soak into the soil surrounding the leach field, sewage may back up into the system
and overflow into the house or puddle on the surface of the ground. There are several possible causes for this problem."
Poor Soil Conditions: Faulty Design or Installation of Septic Systems
A leaching system placed in unsuitable soil, a system that is too small for the house it serves, or an improperly constructed system
may lead to early failure.
Soil Clogging and Septic Systems: If sludge or scum is allowed to escape into the distribution box and from there
into the leach field, the soil will quickly become clogged. If this happens, the liquid will no longer soak, or percolate, into the
soil. This condition can be caused by broken baffles in the septic tank that allow sludge or scum to escape. Failure to have the tank
pumped can also lead to a situation where the sludge and scum overwhelm the baffles. If a steel septic tank has rusted out
and collapsed you should assume that before the collapse it was releasing solids and grease into the absorption system, reducing
High Water Table and Septic Systems:
During wet, or abnormally wet, seasons groundwater may rise into the leach field and force sewage upward to the ground surface.
This condition may mean the system has to be re-installed at a higher level. It may also be possible to intercept the high
groundwater with a series of drains around the system called "curtain drains".
Roots and Clogging of Septic Systems:
The roots of trees and bushes planted too close to the system can sometimes enter and block the pipes of the system.
Removal of the plants and clearing the pipes of the roots is usually required.
Physical Damage to Septic System Components:
Trucks or heavy equipment passing over the system can damage pipes and joints to the point of rendering the system inoperable.
You should be aware of the location of the system and direct traffic to avoid such damage.
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Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf.
Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include
Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and
Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by
Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
Advanced Onsite Wastewater Systems Technologies, Anish R. Jantrania, Mark A. Gross. Anish Jantrania, Ph.D., P.E., M.B.A., is a Consulting Engineer, in Mechanicsville VA, 804-550-0389 (2006). Outstanding technical reference especially on alternative septic system design alternatives. Written for designers and engineers, this book is not at all easy going for homeowners but is a text I recommend for professionals--DF.
Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP;
Quoting from Amazon's description: For the homebuilder, one mistake in estimating or installing wells and septic systems can cost thousands of dollars. This comprehensive guide filled with case studies can prevent that. Master plumber R. Dodge Woodson packs this reader-friendly guide with guidance and information, including details on new techniques and materials that can economize and expedite jobs and advice on how to avoid mistakes in both estimating and construction. Chapters cover virtually every aspect of wells and septic systems, including on-site evaluations; site limitations; bidding; soil studies, septic designs, and code-related issues; drilled and dug wells, gravel and pipe, chamber-type, and gravity septic systems; pump stations; common problems with well installation; and remedies for poor septic situations. Woodson also discusses ways to increase profits by avoiding cost overruns.
Country Plumbing: Living with a Septic System, Hartigan, Gerry: $ 9.95; ALAN C HOOD & TP;
Quoting an Amazon reviewer's comment, with which we agree--DF:This book is informative as far as it goes and might be most useful for someone with an older system. But it was written in the early 1980s. A lot has changed since then. In particular, the book doesn't cover any of the newer systems that are used more and more nowadays in some parts of the country -- sand mounds, aeration systems, lagoons, etc.
Design Manuals for Septic Systems
US EPA Onsite Wastewater Treatment Systems Manual [online copy, free] Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm Onsite wastewater treatment and disposal systems,
Richard J Otis, published by the US EPA. Although it's more than 20 years old, this book remains a useful reference for septic system designers.
U.S. Environmental Protection Agency, Office of Water Program Operations; Office of Research and Development, Municipal Environmental Research Laboratory; (1980)
"International Private Sewage Disposal Code," 1995, BOCA-708-799-2300, ICBO-310-699-0541, SBCCI 205-591-1853, available from those code associations.
"Manual of Policy, Procedures, and Guidelines for Onsite Sewage Systems," Ontario Reg. 374/81, Part VII of the Environmental
Protection Act (Canada), ISBN 0-7743-7303-2, Ministry of the Environment,135 St. Clair Ave. West, Toronto Ontario M4V 1P5 Canada $24. CDN.
Manual of Septic Tank Practice, US Public Health Service's 1959.
Onsite Wastewater Disposal Books
Onsite Wastewater Disposal, R. J. Perkins;
Quoting from Amazon: This practical book, co-published with the National Environmental Health Association,
describes the step-by-step procedures needed to avoid common pitfalls in septic system technology.
Valuable in matching the septic system to the site-specific conditions, this useful book will help you install a reliable system in
both suitable and difficult environments. Septic tank installers, planners, state and local regulators, civil and sanitary engineers,
consulting engineers, architects, homeowners, academics, and land developers will find this publication valuable.
Onsite Wastewater Treatment Systems, Bennette D. Burks, Mary Margaret Minnis, Hogarth House 1994 - one of the best septic system books around, suffering a bit from small fonts and a weak index. While it contains some material more technical than needed by homeowners, Burks/Minnis book on onsite wastewater treatment systems a very useful reference for both property owners and septic system designers.
Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf
Septic System Owner's Manual, Lloyd Kahn, Blair Allen, Julie Jones, Shelter Publications, 2000 $14.95 U.S. - easy to understand, well illustrated, one of the best practical references around on septic design basics including some advanced systems; a little short on safety and maintenance. Both new and used (low priced copies are available, and we think the authors are working on an updated edition--DF.
Quoting from one of several Amazon reviews: The basics of septic systems, from underground systems and failures to what the owner can do to promote and maintain a healthy system, is revealed in an excellent guide essential for any who reside on a septic system. Rural residents receive a primer on not only the basics; but how to conduct period inspections and what to do when things go wrong. History also figures into the fine coverage.
Grass is Always Greener Over the Septic Tank, Bombeck, Erma: $ 5.99; FAWCETT; MM;
This septic system classic whose title helps avoid intimidating readers new to septic systems, is available new or used at very low prices.
It's more entertainment than a serious "how to" book on septic systems design, maintenance, or repair. Not recommended -- DF.
US EPA Onsite Wastewater Treatment Systems Manual Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm
Water Wells and Septic Systems Handbook, R. Dodge Woodson. This book is in the upper price range, but is worth the cost for serious septic installers and designers.
Quoting Amazon: Each year, thousands upon thousands of Americans install water wells and septic systems on their properties. But with a maze of codes governing their use along with a host of design requirements that ensure their functionality where can someone turn for comprehensive, one-stop guidance? Enter the Water Wells and Septic Systems Handbook from McGraw-Hill.
Written in language any property owner can understand yet detailed enough for professionals and technical students this easy-to-use volume delivers the latest techniques and code requirements for designing, building, rehabilitating, and maintaining private water wells and septic systems. Bolstered by a wealth of informative charts, tables, and illustrations, this book delivers:
* Current construction, maintenance, and repair methods
* New International Private Sewage Disposal Code
* Up-to-date standards from the American Water Works Association
Wells and Septic Systems, Alth, Max and Charlet, Rev. by S. Blackwell Duncan, $ 18.95; Tab Books 1992. We have found this text very useful for conventional well and septic systems design and maintenance --DF.
Quoting an Amazon description:Here's all the information you need to build a well or septic system yourself - and save a lot of time, money, and frustration. S. Blackwell Duncan has thoroughly revised and updated this second edition of Wells and Septic Systems to conform to current codes and requirements. He also has expanded this national bestseller to include new material on well and septic installation, water storage and distribution, water treatment, ecological considerations, and septic systems for problem building sites.