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CESSPOOLS for onsite wastewater disposal - What is a Cesspool? What Cesspool Maintenance is Needed? How do Cesspools Fail? InspectAPedia®  -     Septic cesspool design & inspection manual Definition of a cesspool, why a cesspool is not a drywell, why their function is limited How do cesspools fail? How old is the cesspool? Important life safety warnings regarding cesspools

This document explains 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.

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CESSPOOLS for WASTEWATER - for onsite wastewater disposal

What is a cesspool? A cesspool combines the septic treatment tank and absorption system into a single component.

In its most basic and traditional form a cesspool is a hole in the ground to receive sewage: the walls of the "hole" are lined with stone or concrete block or (safer) pre-cast concrete (photo) to form a masonry-lined pit into which sewage is discharged. Solids (sewage from the building) remain in the pit, effluent is absorbed into soil below and at the sides of the cesspool. Solids settle to the bottom, floating grease and scum collect at the top, and liquid seeps into the ground, initially through the bottom and most of the time through the side of the cesspool.

Cesspools as a means to dispose of sewage have been around since the late 1400's at the beginning of the Renaissance. (Before that people simply tossed their night soil into the street.) While cesspools have been used for a long time, since the development of the more modern septic system (tank and drain field) cesspools have often used where there is limited physical space (no room for a leach field), and perhaps where the soil absorption rate was high such as areas of gravel or sandy soils.

For most buildings and onsite waste disposal installations which use a "cesspool", you should consider the use of a cesspool as an obsolete, limited capacity system likely to need replacement, and involving significant cost. Some immediate concerns are stated next.

Cesspool Failure Criteria (MA)

Failure Criteria for Cesspools: If the waste level is within 12" of the inlet pipe near the top of a cesspool the system is at end of life and needs to be replaced. Some municipalities and experts will state other distances. In Massachusetts according to the Massachusetts Title 5 Septic Law the following are considered a failed or unacceptable cesspool installation:

• Less than 6inches of freeboard in the cesspool - this means that the top of sewage inside the cesspool is within six inches of the bottom of the inlet pipe
• Less than 1/2 day's storage - the free volume (air) inside the cesspool is less than will hold the number of gallons of waste and wastewater equaling the typical daily use of the cesspool system
• Cesspools located within100 ft. of a pond or dug well (surface water supply) are unacceptable
• Cesspools located within 50 ft. of a private well (modern sanitary well) are unacceptable
• Cesspools located between 50 and 100 ft from a private well if the well fails bacteria test are also unacceptable
• In some states including Massachusetts, cesspools located within Zone 1 of a public well are considered failed and unacceptable
• In most jurisdictions, board of health (BOH) evaluation is required if a cesspool is located within 50 feet of any surface water such as a lake, pond, stream, or river.

A cesspool needs replacement if it meets any of these failure criteria. While a septic company may offer to pump, partially pump out, or agitate or aerate the bottom sludge in the cesspool in an effort to extend its life, these procedures are potentially very dangerous (see Cesspool safety Warnings and at best will give only temporary relief.

Where a new cesspool of traditional sort is going to be installed you should at least use a concrete pre-cast model with a safe cover (see photos at left and above).

Fortunately there are alternative onsite wastewater disposal alternative designs which can handle limited or even zero-space sites, so a simple cesspool as a destination for blackwater is no longer the only choice for limited-space sites.

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.
• Safety Warning: 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 summary about cesspool hazards: 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.

Cesspool Capacity and Testing Limitations

Cesspools can obscure or prevent effective septic loading and dye testing: If a cesspool is in use at a property a septic dye test would not be a reliable indication of good system condition since the test could simply be trying to fill a large near-empty hole in the ground; yet such a system may fail soon after being returned to active or heavier regular use.

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SEPTIC DESIGN ALTERNATIVES
  Wastewater Treatment Levels
  Wastewater Dispersal Methods
  Master List of Septic System Types
  AEROBIC 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

• Biomat Formation in the Septic System Drainfield Absorption System - what leads to drain field clogging and expensive drainfield repairs
• Cesspools for onsite wastewater disposal
• Cesspool Safety
• 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.
• ...

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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