Environment & Inspections

Algoma Public Health

Class 3 - Cesspool

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Usually used in addition to a Class 2 Greywater Leaching Pit, this type of system can only be used to dispose of waste from a Class 1 (Privy) sewage system. Some models of composting toilets are equipped with an overflow device, or where a pail privy is being used, this method of sewage disposal may be installed.


If you would like to learn more please call the Environmental Health team at 705-759-5286.


Like Class 2 Leaching Pit, the Cesspool method of sewage disposal can only be used if the daily sewage flow is less than 1,000 litres per day. For the traditional cottage, the anticipated daily sewage flow would be considerably less than this limit. In order to calculate the expected daily overflow from a composting toilet, you will need to check with the manufacturer to calculate the anticipated overflow on a day to day basis.


When constructing a cesspool, the Ontario Building Code stipulates that:

  • The bottom of the cesspool shall be at least 900mm above the high groundwater table.
  • The cesspool shall be constructed in such a manner as to prevent the collapse of its sidewalls.
  • Any material used to support or form the sidewalls of the cesspool shall be an open-jointed material of a type that will permit leaching from the cesspool.
  • The cesspool shall be provided with a tight, strong cover that shall remain over the cesspool except when it is necessary to remove it for the purposes of adding sanitary sewage to or removing sanitary sewage from the cesspool, or for the purpose of maintenance of the cesspool.
  • Where the cesspool extends to the ground surface, the cover required shall be lockable.
  • The soil or leaching bed fill around the perimeter of the cesspool shall be raised or mounded to the height of at least 150mm above the surrounding ground surface.
  • The surface of the ground in the area of the cesspool shall be so graded that surface drainage in the area will be diverted away from the cesspool.
  • The cesspool shall be surrounded on all sides and on its bottom by at least 600mm of soil or leaching bed fill, except the top where the cesspool extends to the surface of the ground.


If you are considering using a composting toilet, equipped with an overflow pipe, or a pail privy, please check the chart below for clearance distances.


  Minimum Horizontal Distance in Metres From:  

A well with a water tight casing to a depth of at least 6 metres (Drilled Well)

A Spring used as a source of potable water or well other than a water tight casing to a depth of 6 metres (Shallow Well) A lake, river, pond, stream, reservoir, or a spring not used as a sources of potable water A property line


60 30 15 3

*Please check with the municipality governing the location you are installing the system in to see if there are increased clearance distances in place - if so, the greater distance must be followed.


Typical Cesspool


Diagram of Cesspool



Cesspools are generally discouraged because the human waste added to the cesspool will cause the soil to clog which can reduce the life expectancy of the cesspool. Applicants considering utilizing a cesspool are encouraged to explore other methods of sewage disposal. If after time your cesspool does begin to fail or malfunction, contact the nearest office of the Algoma Public Health for information on maintenance and repair or replacement requirements.



Class 3 systems are best used in conjunction with a separate Class 2 system used for greywater waste. Class 3 systems are not designed to handle waste flows other than toilet waste. It is, essentially, an outhouse without the above-ground structure.


Please not that these forms are not intended to be a comprehensive interpretation of the OBC design standards, but simply an aid for common installations. If you have any further questions about design or construction it is recommended you contact a licensed Designer or Installer.


Date of Creation: June 1, 2015

Last Modified: June 1, 2015