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Septic system life expectancy:
This document describes the typical life expectancy of septic systems and various common septic system components. The life expectancy of a septic tank depends largely on its materials, while the life of septic system piping
depends largely on the risk of damage from vehicle traffic, clogging by roots, or flooding by groundwater.
expectancy of a drainfield varies widely by installation type (conventional soil absorption system versus a sand bed
filter, for example), by soil conditions (clay or rock or sand), and importantly, by the frequency of maintenance and cleaning
which has been performed on the septic system.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Septic System Component Life Expectancy
Understanding the proper procedures for septic tank care, septic tank cleaning frequency, and other septic tank maintenance chores,
will permit the owner of a home with an onsite septic system to maximize the life of the system and to assure that it is
How Quickly Does A Septic System Fail? How long will a septic tank, D-box, or absorption bed last?
Septic Tank Pumping Frequency: providing you are starting with a functional and reasonably-designed septic
system, the most significant step you can take to extend the septic system life is to have the septic tank
cleaned or "pumped" on schedule.
See TANK PUMPING SCHEDULE
for a table that determines how often a particular septic tank needs this service.
How the Septic System is Used: including the wastewater usage level and what materials are flushed
down the septic system drains. Conserving water reduces the load on the absorption field. Avoiding flushing
chemicals or items that don't biodegrade reduces the solid build-up rate in the septic tank.
See "Don't Flush these things into a septic system"
for a list of what's ok and what's not ok to put into septic tanks and building drains.
Soil Conditions such as the soil percolation rate and the amount and level of ground water or surface
water that affect the soil absorption area or drain field.
Septic Tank Materials: a steel septic tank rusts away, first losing its baffles (which lead to
drain field clogging) and eventually rusting at its bottom or sides. The rate of rust depends on the
soil conditions and soil acidity and other factors. A concrete septic tank can have a very long life, in excess
of 40 years, except for cases of poorly-mixed concrete or possibly acidic soils which may reduce that span.
Plastic or fiberglass septic tanks can expect to have a similar life unless they are mechanically damaged.
Life of Special Components such as effluent pumps or septic grinder pumps, septic filters,
septic media, and sand bed filter systems often determines the need for repair of alternate-design
septic systems that use these components.
Nearby trees or plants whose roots invade system components.
Water & wet sites: sending surface or roof runoff into a drainfield area or locating a septic soakaway bed in wet soils, near a high water table, near creeks or streams prone to flooding all mean short life as well as maybe an improper or illegal installation.
Water usage in the building: tThe level of water usage in a building also affects the drainfield and unusual or abnormal levels of water usage, such as constantly running toilets (TOILET RUNS CONTINUOUSLY) or a water softener stuck in "backwash" cycle, can saturate a septic drainfield and cause it to fail. And a water softener or water conditioner that is improperly adjusted and puts too much salt into the water also is harmful to the drainfield.
How Quickly Will the Septic System Fail if We Have One or More of the Problems Listed Above?
Septic systems (tank and absorption system, or onsite wastewater disposal systems) will
not fail immediately if they are not pumped. However, an un-maintained septic tank is no longer protecting the soil
absorption field from solids.
Continued neglect shortens the drain field life and
may result in system failure and even require complete replacement of the soil absorption
field. In some cases, site limitations may make replacement of the absorption field impossible - at least impossible
using a conventional drainfield design. Alternative designs are available to solve these problems.
So provided you've addressed these factors in septic system life, how long can you expect a septic
system to last before costly repairs to the septic tank or septic drain field are required?
How Long do Individual Septic System Components like Tanks, Piping, D-Boxes, Filters or Pumps Last?
A steel septic tank will rust out on a schedule affected by soil acidity and tank steel quality and coating
integrity. A steel septic tank more than 15 or 20 years old is likely to have already rusted to the point of
having lost its baffles and perhaps having a rusted-out bottom - conditions that can be recognized during
septic tank cleaning and inspection. A steel septic tank cover lasts until some fool drives over it or it
A concrete septic tank can last 40 years to nearly indefinitely, though poor quality concrete or acidic ground
water may result in deteriorated baffles or tank components.
A conventional septic drain field has a varying life as a function of the soil percolation rate,
drainfield size, and usage level. I've seen a septic drainfield, a large one in good soil with a well
maintained septic tank, last for more than 50 years. I've seen a conventional septic drainfield
fail within 24 hours of first use on a new system when piping was poorly installed.
There is therefore
a very wide range of life for this component. Experience of neighbors who have similar soils and
similar systems can be helpful if you ask. In general, if I know nothing but that there is a conventional
septic drainfield or a raised bed system and it's 20 years old, I consider its forward life not
predictable and advise owners to budget for its replacement at any time.
The septic tank is only one part of an on-site wastewater system. It is designed to remove solids prior to the
effluent entering the soil absorption field, provide for the filtration, digestion of a portion of those solids, and
storage of the remaining solids.
Taking care of the septic tank will, however, extend the life of the costly second
half of the onsite wastewater treatment system - the absorption system, leach field, or drainfield.
What to Do if you have just moved into a home with a septic system
If you've just moved into a home with a septic tank you may not know the size of the septic tank, its maintenance
history, or even where the septic tank is. In this case, you should have the
tank pumped and inspected. The company pumping the tank will tell you its size, age, and condition.
Continue reading at SEPTIC DRAINFIELD LIFE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see these
Details about the life expectancy of a septic system
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septic system installation in Newfoundland, Canada lasted 60 years
(May 15, 2014) Art Mercer said:
In 1958, as a boy of 14 years, I helped my father install a concrete septic tank for our home in Newfoundland, Canada. We dug a septic field behind the house (rural property) using 8" pieces of aluminum piping. This septic system has been used constantly since that date (over 60 years) and it has never been opened. Later this week my brother (who was not even born then)will switch the system to the local town septic system. I wish my father was alive to realize the feat that he acomplished so many years ago.
Thanks for the success-report Art. Indeed there are some old, still functioning septic system drainfields. Often I see that soil properties are key in the successful disposal of effluent.
As a different data point, in 1998 I excavated a system built in 1920 that was still "functioning" supporting the home of a single elderly occupant who had observed odors around the septic tank. We found that there was no drainfield, not even a seepage pit. A short pipe exited the septic tank into the "ground" that was in this case largely gravel. Effluent was disposed-of, though the level of treatment was probably minimal.
Question: 36 year old septic systems: contractor wants too much to do a repair
Oct 22, 2014) Sherry Lewis said:
My septic system is 36 years old. It is concrete (if the stand pipes are concrete I assume the tank is), it has two tanks (I'm told the second is an overflow tank), the soil in my area is mostly sandy (nearby ocean) and for about 30 years I have been the sole occupant in my house. Plus, I use the disposal only for the smallest bits of food that slip into it, don't put anything in the system other than water, soap, the slight disposal waste and toilet waste. I have the system pumped on the average of every other year.
Recently when it was pumped I had called them due to air bubbling out of my downstairs toilet and a friend suggesting that spelled trouble and a full tank. It was at the 2 year mark. The pumper fellow said primarily due to the age of the system, it was probably due for replacement, either entirely or at a minimum the leach field.
#1) Is age alone the primarily indicator for replacing the system?
#2) When talking to a contractor to do the job he said it would require a lift station due to my high ground water (8'). He said that if the sewage pipes in my house were located somewhat high in the ground the lift pump would not be required, however, a high water table issue has inundated over 50 homes barely 5 miles away and indications are that "it" (the high water) is moving my way.
He did recommend the lift station without coming to check my current sewage pipe depth and I'm going to call him to do so rather than him assuming they will not accommodate a standard system as I have now. I don't know what the water table level was when the house was built but I suspect a was a bit lower than 8'. Finally, the fellow who came to dig the test hole, looking for the water level, indicated an approximate cost of $7,000 or a touch more if I declared 4 rather than 3 bedrooms. The contractor who will do the replacement work indicated a price right at DOUBLE that amount due to the lift station! That seems obscenely high! Please help! Thank you very much.
Question: warn home buyers to inspect the septic system
(Feb 13, 2015) Harry Ford said:
You should probably advise the new home owner to have the septic inspected before they purchase the home.
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
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.
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