Classes of sewage systems - Definitions

• Class 1- a chemical toilet, an incinerating toilet, a recirculating toilet, a self-contained portable toilet and all forms of privy.  See diagrams of Pit Privy and Vault Privy.
• Class 2- grey water system. See diagram of Grey Water Pit.
• Class 3- a cesspool.
• Class 4- a leaching bed system including sewage systems utilizing treatment units
• Class 5- a system which requires or uses a holding tank for the retention hauled sewage at the site where it is produced prior to its collection by hauled sewage system. See diagram of Holding Tank installation.

CLASS 1 SEWAGE SYSTEMS

Class 1 sewage systems shall receive or be used only for the disposal of human body wastes. This classification includes various types of toilets and privies.

The following sewage systems are included in Class 1.

1. A chemical toilet
2. A recirculating toilet
3. An incinerating toilet
4. A self contained portable toilet
5. All forms of privy including a portable privy, an earth pit privy, a pail privy, a privy vault and a composting toilet system.

CLASS 2 SEWAGE SYSTEMS

Class 2 sewage systems shall receive or be used only for the disposal of sewage other than human body waste. A leaching pit is classified as a class 2 sewage system.

Use of Class 2 Sewage Systems

1. Leaching pits provide a suitable system for disposing of "grey" water when the daily amount of such waste is small and site conditions are favourable. They are normally paired with class 1 sewage systems in cottages where the water is hand carried, serviced by a hand pump or serviced by a gravity fed water system.  Higher daily sewage flows soon overload a small leaching pit, or require pits of such proportion as to be impractical. In most areas where class 2 sewage systems are used the soil cover is limited. This further restricts their use in any situation but for low flows.

  Location of Class 1, 2 Sewage Systems clearances measured horizontally in metres    

CLASS 4 SEWAGE SYSTEMS

A class 4 Sewage system is a leaching bed system and consists of a treatment unit connected to a leaching bed constructed in accordance with the requirements of the Ontario Building Code. The principal components, and the action that takes place in these components, are:

1. The septic tank which received sewage from the building sewer, and in which solids are settled to improve the quality of the sewage prior to its movement to the leaching bed. Anaerobic bacterial action breaks down much of the solid matter to liquids and gases. The tank design allows for the storage of the solid matter, that rises to the surface to form a scum and that, which settles to the bottom to form sludge. If the accumulation of sludge and scum is kept within limits by periodic cleaning, the tank should provide reliable service.
2. The leaching bed received the liquid effluent from the tank. This sewage still contains solids and is highly charged with bacteria and nutrients. The sewage is distributed in the leaching bed by means of distribution pipes set in a stone layer located in the absorption trenches or above a filter medium. The sewage percolates downwards through the soil where it receives treatment due to the action of aerobic bacteria in the pores of the soil. The key to the design of an efficient leaching bed is the assessment of the soil and of the highest level of the water table in the area of the proposed bed.

A filter bed is a unique leaching bed that uses imported granular materials with a specified percolation rate and is specially engineered.

See other diagrams - typical layout of system, sectional view of raised system, idealized soil sections.

Note: the Health Unit is only responsible for sewage systems which would receive a daily sewage flow of less than <10,000 litres/day. This includes a total sewage flow created on a single registered lot not only for 1 single system.

CLASS 5 SEWAGE SYSTEMS

A class 5 sewage system is a sewage system that requires or uses a holding tank for the storage or retention of sewage at the site where it is produced prior to its collection by a hauled sewage system.

The Building Code (Chapter 8) specifies under what conditions a Class 5 system may be installed.