PHOTO of a septic seepage pit collapse when a truck drove over it.

Septic & Cesspool Safety Guide for Homeowners

Septic & Cesspool Safety:

This document describes key septic system collapse and sinkhole safety warnings for homeowners and home buyers of properties using onsite septic systems and cesspools.

Septic tanks, cesspools, and drywells present serious hazards including septic cave-in's or collapses, methane gas explosion hazards, and asphyxiation hazards.

Simple precautions which we describe here can help avoid a dangerous or expensive septic problem.

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SPECIAL SEPTIC SYSTEM SAFETY WARNINGS FOR HOME OWNERS - Septic System Warnings for Home Owners and Home Buyers

Septic system concerns for a building owner start with safety. The photograph at the top of this page shows what can happen when a truck drives over a cesspool, drywell, or seepage pit.

Luckily in this case no one was injured, but the seepage pit was destroyed and significant costs were involved in installing a new seepage pit as well as in repairing the soils compacted and damaged by the heavy equipment necessary to pull this dump truck out of the pit into which it fell.

Here are some red flags that suggest collapse hazards at septic systems, cesspools, drywells, or seepage pits:

  • Signs of collapse-possible fatal hazards: include depressions or "soil subsidence" anywhere on or around the property. Any suspect area should be roped-off and absolutely no one should walk over or even close to such a spot until it has been investigated by a professional.
  • Odors: sewer gas is explosive. A septic backup, contamination, or blockage or simply improper drain-waste-vent piping installation can leak dangerous sewer gas into a building where a spark can cause an explosion.
  • Old or abandoned septic or cesspool systems: such as site-built cesspools or drywells were often made with a thin steel or wood cover which with age can collapse. If the history of the site or visual observation suggests that there are or were old systems at the property, professional investigation is warranted. Improper "abandonment" (failing to fill-in a pit) can lead to sudden collapses.

    Signs that there may be old systems at a property might come from anecdotal evidence (ask a neighbor, ask the local septic installing or service companies), or visual evidence such as seeing abandoned waste pipes at basement or crawl space walls or floors. Don't assume that an old house which is now connected to the public sewer didn't previously have an on-site waste disposal system.
  • Septic service by untrained workers: such as aerating, agitating, or pumping out an old site-built cesspool, can lead to sudden system collapse. Prevent access over or near any such systems.
  • Unsanitary conditions such as discharge of sewage effluent to the yard surface, to a nearby well or stream, or previous septic backups into a building deserve professional attention. Indoors special cleaning may be needed to remove bacteria or other pathogens.
  • Septic testing by inexpert "inspectors" who may not follow an adequate procedure increases the risk of a costly surprise.
  • Uninformed or inexperienced homeowners may not notice a danger or malfunction. Homeowners should review the Septic System Safety Warnings listed above If your home uses a cesspool, drywell, or seepage pit, be sure to review our Cesspool Safety Warnings - Specific Warnings about Cesspool Collapse Hazards.\
  • Cesspools or drywells that are constructed of dry-laid stone or concrete block, are especially at risk of sudden collapse if a septic service company has pumped down the sewage level in the cesspool and that risk is still greater if someone has attempted to "restore" cesspool operation or function by aerating or jetting or agitating the sludge layer on the bottom of the unit.
  • The information here is general in nature. Since conditions and requirements vary widely at individual sites, the you should obtain qualified expert advice pertaining to the specific system about which you have questions, and should not rely on this general text for costly diagnostic/repair/replacement decisions.

Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved to the author. Technical review by industry experts has been performed and is ongoing - reviewers are listed at "References."

This article is part of our series: INSPECT TEST & MAINTAIN SEPTIC SYSTEMS


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