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 Inspecting, Testing, & Maintaining Residential Septic Systems - Cesspool Collapse Hazards
- Cesspools for onsite wastewater disposal - Cesspool Collapse Warnings and Cesspool Safety
- Warnings about cesspool collapse and fatality hazards
- Cesspool rejuvenation, agitating, jetting, or hydrojetting cesspools vs when to install a new cesspool or drywell
- CESSPOOL SAFETY WARNINGS
- CISTERNS - separate article
- METHANE GAS SOURCES & SEPTIC SYSTEM & SEWER GAS ODORS - separate articles
- SEEPAGE PITS - separate article
- SEPTIC TANK ABANDONMENT GUIDE - separate article
- SEPTIC & CESSPOOL SAFETY - separate article
- SPECIAL WARNINGS FOR HOME OWNERS - separate article
- Questions & Answers about safety hazards, collapses, explosions, fires, toxics, injuries and fatalities involving septic tanks, cesspools, drywells, and other septic system components
- References
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Septic & Cesspool or Drywell Safety Hazard Warnings: this document explains and describes some critical safety concerns for people owning and maintaining cesspools for onsite waste treatment. Cesspools, depending on how they have been constructed and how they are serviced, can present particularly dangerous
conditions and risk collapse and fatal injury. The hazards described here in discussing cesspools can also be present
at drywells and seepage pits.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Cesspool Safety Warnings and Cesspool Capacity Limitations
 Readers trying to diagnose and deal with sudden soil subsidence or yard collapses should see CESSPOOL SAFETY WARNINGS as those hazards can also apply to drywells and septic tanks, and also see SINKHOLES, WARNING SIGNS. Additional septic system safety warnings are at SEPTIC & CESSPOOL SAFETY. Quoting from our sink holes article:
The bare minimum that a property owner needs to know about sinkholes or any other sudden subsidence
of soils at a property is that these conditions might be very dangerous.
Someone falling into a sink hole
or into a collapsing septic tank could be seriously injured or even die. If a suspicious hole, subsidence,
or depression appears at a property the owner should rope off and prevent access to the area to prevent
anyone from falling into the opening, and then should seek prompt assistance from a qualified expert,
geotechnical engineer, septic contractor, excavator, or the like.
This document is a subchapter of our online text about cesspool design, cesspool installation, cesspool maintenance and cesspool inspection. These pages explain what a cesspool is, gives important safety and maintenance advice for cesspool systems, and defines the
criteria for cesspool failure.
We also provide critical safety warnings concerning cesspool systems as with some older and especially site-built cesspools there is a risk of dangerous collapse or cave-ins.
This material is a chapter of our Septic Systems Online Book: That document explains septic system inspection procedures, defects in onsite waste disposal systems, septic tank problems, septic drainfield problems, checklists of system components and things to ask. Septic system maintenance and pumping schedules.
Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information in books or pamphlets for sale is reserved to the author.
Some technical review by industry experts has been completed-reviewers are listed at "References."
Review comments and content suggestions are invited. Home buyers should see the Home Buyer's Guide to Septic Systems.
Also see Septic & Cesspool Safety - Septic System, Septic Tank, & Cesspool Safety Warnings for Septic Inspectors, Septic Pumpers, and Homeowners.
Also see The Septic Systems Home Page.
Very Important Cesspool Safety Warnings
- Safety Warning: do not walk over the top of or close to the edges of a cesspool or any other onsite pit or excavation because
of the danger of fatal collapse. Keep pets and children away from such systems.
Our photo (left) shows a sudden back yard collapse that may have been due to an old drywell or cesspool, discussed in detail at Sinkholes in New York.
- Safety Warning: there is a high risk of cesspool collapse, risking fatality if someone falls in to one of these
systems. This is particularly true for older site-built systems that were often made of dry-stacked stone or concrete block,
and more-so if such systems are not protected by a very secure cover.
- Safety Warning: pumping cesspools is dangerous since older site-built systems may be more likely to collapse inwards
when relieved of their contents. Also, pumping a cesspool from the bottom, in an attempt to break up the sludge layer and "rejuvenate" the cesspool is likely to undermine the structure's walls and in the case of dry-laid concrete block or stone, as we warn just below, can lead to a dangerous and sudden collapse of the cesspool.
Experienced septic pumpers who attempt this "cesspool rejuvenation" method despite severe safety warnings not to do so, will still avoid pumping much waste out of the cesspool in hopes to avoid a collapse.
- Hydrojetting a pre-cast cesspool in good condition and standing on stable soil (not sand) may be less dangerous and is usually performed after a partial pumpout. Before taking any action, review your cesspool repair plan with your local health and building departments for both building code and site safety concerns can be grave when a cesspool is disturbed.
- Safety Warning: hydrojetting a cesspool, aerating or agitating sludge at the bottom of a cesspool in an attempt to renew its function or extend its
life also risk system collapse - in particular if the cesspool is an older type of site-built structure, typically made of dry-stacked stone or concrete blocks, jetting the cesspool bottom, and even pumping out the cesspool can undermine the cesspool walls leading to collapse of the system. We are informed of a serious fatality involving a cesspool that was jetted and then collapsed, burying the owner. Don't do this.
Cesspools that are collapse-resistant pre-cast concrete structures are safer in this regard. However many municipalities define the end of life of a cesspool in terms of its static full level and do not provide for rejuvenation attempts. See CESSPOOL FAILURE CRITERIA.
- Safety Warning: do not drive over cesspools (nor over septic tanks, septic piping, or drainfields) as there is risk of collapse or cave-in. The photographs of a collapsed
seepage pit (which could as well have been a cesspool collapse) at the top of
this page and just below show what happens when a heavy truck drove over a seepage pit which was not designed to carry such a heavy traffic load. See DRIVING or PARKING OVER SEPTIC
In Summary: watch out for cave-ins, keep away: cesspools, particularly older site-built
cesspools present a very high risk of collapse from an unsafe cover or following some types of service involving
pumping, aeration, or hydro-jetting.
Adults or children should not walk over or even near cesspools because of
the risk of falling-in followed by collapse, a virtually certain cause of death. If the presence of a cesspool
is known or suspected at a property its location should be roped off to prevent access and it should be investigated by a professional.
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When to Install a New Cesspool or Drywell
Question: When is the best time to install a new cesspool?
I need a lot of information because I am going to buy a new cesspool. When is the best time to buy one? I was told winter is the best time to buy a new cesspool? But the ground is frozen now. What temp is right? What is the average price? House was built 1950 (maybe). Does new cesspool come with new cover? Can I have my clothes line on top of old cesspool? How do I get rid of odor in my basement? When they put the new cesspool in do they check pipelines in and out of house? If so how? Do I need to get new pipes in side? Does a plumper know best, when to replace pipes? - S.H.
Reply: Wet warm weather
The season in which a cesspool is to be installed affects the cost and may affect the outcome too:
- If the ground is frozen it may cost more to excavate to install the cesspool, and of course if there is very deep snow cover it may be difficult to deliver the unit and drop it into the new hole as well as to deliver the necessary gravel underneath and around the unit.
- If the ground where you intend to install a cesspool is found to be flooded - which you can discover if the excavation is performed in the in wet season - you will know the cesspool won't work in that location
So it's probably cheaper and smarter to dig during the un-frozen wet season.
Of course, if your building relies on a cesspool or drywell to function and the present system has failed, you may be forced to install the new cesspool or drywell without waiting.
Cesspool cover:
Cesspools, if you buy a pre-fab pre-cast unit, are made of concrete. You may have a choice of cover - a heavier duty one that can be driven-over without collapsing is smart. But a safe cover must be included in your bid price regardless.
Watch out: falling into a cesspool or drywell is likely to be fatal. See SEPTIC & CESSPOOL SAFETY
Putting a Clothes Line over a Cesspool:
A clothes line won't hurt the cesspool if you don't drive a post into the cesspool top.
Getting rid of Old Sewage Backup Odors:
Odors go away by cleaning and sanitizing the area of any sewage backup and airing it out. If odors remain you may have an outdoor failure and outdoor sewage odors as a source, or you might have an indoor plumbing vent problem.
See ODORS & SMELLS DIAGNOSIS & CURE for details.
Building Codes, Permits, Approvals for Cesspools and Drywells
You need an experienced plumber and cesspool. installer to help locate the new cesspool, connect existing building drains to it, and to assure that the building drain/waste/vent piping are working properly.
Don't forget to obtain a building department or health department permit and approval, and to install it correctly and safely.
Watch out: Some municipalities do not allow cesspools - so check with your building department. .
See these articles about cesspools
CESSPOOLS
CESSPOOLS for WASTEWATER
CESSPOOL FAILURE CRITERIA
CESSPOOL AGE ESTIMATES
Frequently Asked Questions (FAQs)
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Questions & answers or comments about safety hazards, collapses, explosions, fires, toxics, injuries and fatalities involving septic tanks, cesspools, drywells, and other septic system components.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- Thanks to Denise Cermola for permission to use the photo at page top (email 11/16/06 to 12/10/06). The contractor drove over this seepage pit connected to septic tank and caused total destruction of the system. Luckily there were no injuries in this event.
- Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06
- Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com 11/06
- Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY. 11/29/06
- Thanks to reader - S.H. for discussing the timing of when to install a new cesspool, February 2011
- Cesspool Safety - Specific Warnings about Cesspool Collapse Hazards (this document)
- Septic & Cesspool Safety - septic system, septic tank, & cesspool safety warnings for septic inspectors, septic pumpers, and
- Septic Safety: Septic System, Septic Tank, & Cesspool Safety Warnings for Septic Inspectors, Septic Pumpers, and Homeowners
- Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location - these methods also apply to locating a cesspool or drywell at a property.
- When Not to Pump a Septic Tank to avoid damage, unsafe conditions, or wasting money
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.
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- 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), Advanced Onsite Wastewater Systems Technologies.
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 we 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.
- 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. (DF volunteers to serve as indexer if Burks/Minnis re-publish this very useful volume.)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. We refer to it often.
While Minnis says the best place to buy this book is at Amazon (our link at left), you can also see this book at Minnis' website at http://web page .pace.edu/MMinnisbook
- 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
- Soil Percolation Tests soil perc testing guide and instructions
- Percolation Testing Manual, CNMI Division of Environmental Quality, PO Box 501304, Saipan, MP 96950
- Planting Over Septic System Component", Daniel Friedman (author/editor, InspectAPedia.com), The Innovator, Winter/Spring 2008, BCOSSA, British Columbia OnSite Sewage Association, 201-3542 Blansard St., Victoria BC V8X 1W3 Canada
- Save the Septic System - Do Not Flush These Items Down the Toilet, Daniel Friedman, InspectAPedia.com - PDF document, printable
- SEPTIC STANDARDS
- 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.
- Test Pit Preparation for Onsite Sewage Evaluations, State of Oregon Department of Environmental Quality, Portland OR, 800 452-4011. PDF document. We recommend this excellent document that offers detail about soil perc tests, deep hole tests, safety, and septic design. Readers should also see Soil Percolation Tests and for testing an existing septic system, also see Dye Tests
- 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.
- The NSFC Products List has an excellent list of design manuals/modules available from their website or by telephone 800-624-8301
- Submissions welcome. send us a suggested document link or request an exchange of website links
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