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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.

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.

© Copyright 2009 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.

Cesspool Safety Warnings and Cesspool Capacity Limitations

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.
• 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 Components?

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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SEPTIC SYSTEMS HOME
HOME BUYERS GUIDE to SEPTIC SYSTEMS
SEPTIC SYSTEMS ONLINE BOOK
INTRODUCTION
SEPTIC SYSTEM SAFETY WARNINGS
SEPTIC SYSTEM DESIGN BASICS
  SEPTIC SOIL & PERC TESTS
  SEPTIC TANK SIZE
  SEPTIC TANK DEPTH
  SEPTIC TANK TEES
  SEPTIC DRAINFIELD SIZE
  SEPTIC DRAINFIELD SHAPE
  SEPTIC CLEARANCES
  SEPTIC TANK PUMPING FREQUENCY
  SEPTIC TANK PUMPING PROCEDURE
  SEPTIC PUMPING REPAIR
  SEPTIC TREATMENTS
SEPTIC SYSTEM DESIGN ALTERNATIVES
  Wastewater Treatment Levels
  Wastewater Dispersal Methods
  Master List of Septic System Types
  AEROBIC SEPTIC SYSTEMS
  ALTERNATING BED SEPTIC SYSTEMS
  CESSPOOLS
  CESSPOOLS for WASTEWATER
  CESSPOOL FAILURE CRITERIA
  CESSPOOL AGE ESTIMATES
  CESSPOOL SAFETY WARNINGS
  DRYWELLS
  SEPTIC EFFLUENT DISINFECTION SYSTEMS
  EVAPORATION-TRANSPIRATION SEPTIC SYSTEMS
  FIXED-FILM PROCESS SEPTIC SYSTEMS
  GRAVELLESS SEPTIC SYSTEMS
  LAGOON SEPTIC SYSTEMS
  PRESSURE DOSING SEPTIC SYSTEMS
  MEDIA FILTER SEPTIC SYSTEMS
  SEPTIC & GREYWATER FILTERS
  SEQUENCING BATCH SEPTIC SYSTEMS
  MOUND SEPTIC SYSTEMS
  RAISED BED SEPTIC SYSTEMS
  SAND BED SEPTIC SYSTEMS
  SEWAGE TREATMENT SYSTEMS
  TOILET ALTERNATIVES
  VEGETATED SUBMERGED SEPTIC BEDS
  WETLAND SEPTIC SYSTEMS
  ALTERNATIVE SEPTIC DESIGNERS
  ALTERNATIVE SEPTIC PRODUCTS

• 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

More Reading about Cesspool, Drywell, and Seepage Pit Safety, and Septic System Maintenance and Repair:

• 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 homeowners.
• Septic D-BOX Inspection provides for help in finding and inspecting the septic system drainfield distribution box


• Biomat Formation in the Septic System Drainfield Absorption System - what leads to drain field clogging and expensive drainfield repairs Cesspools for onsite wastewater disposal
• Drywells for onsite wastewater or graywater disposal
• Don't Flush these things into a septic system: a list of what's ok and what's not ok to put into septic tanks and building drains
• 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.
• Inspecting & Testing Septic Systems: Online Book, Inspection, Test, Diagnosis, Repair, & Maintenance: Our Online Septic Book: Septic Testing, Loading & Dye Tests, Septic Tank Pumping, Clearances, details of onsite waste disposal system inspection, testing, repair procedures.
• Dye Tests: how to perform a Septic Loading and Dye Test - septic dye testing procedures in complete detail, a septic function test - a chapter in the above book.
• When Not to Pump a Septic Tank to avoid damage, unsafe conditions, or wasting money

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• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
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More Information on Building Diagnostic Inspections and Repairs

• The Septic System Information Website - Extensive, Detailed Consumer and Industry Information on Septic System Inspection, Testing, Maintenance, Alternatives for on-site waste disposal

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