(formerly 08-02)

Legislative Authority: Ontario Water Resources Act

Responsible Director: Director, Approvals Branch

Last Revision Date: April, 1994


The primary purpose of this guideline is to reduce/minimize the potential for health hazards to water users in the event of a watermain or sewer line rupture that could result in contamination of the water distribution system. The guideline is supported by Procedure F-6-1: "Procedures to Govern the Separation of Sewers and Watermains" (July, 1984, as amended).

Definition (1)

Sewage/sewage works
Includes sanitary sewers, sanitary forcemains, storm sewers, and storm forcemains, together with all appurtenances and fittings.

Rationale (2)

Sewers/sewage works and watermains located parallel to each other shall be constructed in separate trenches maintaining a minimum clear horizontal separation distance of 2.5 metres in accordance with the Procedure F-6-1: "Procedures to Govern the Separation of Sewers and Watermains", dated July 1984, as amended.

In cases where it is not practical to maintain separate trenches or the recommended horizontal separation distance cannot be achieved, the Ministry, in accordance with the above-noted procedure, may allow deviation from the separation requirements.

Hazards due to Contamination (3)

Contaminated ground and surface water may enter the water distribution system through leaks or breaks in the piping, vacuum air relief valves, blow-offs, fire hydrants, meter sets, outlets, etc. with the occurrence of negative internal or positive external pressure. Water pressure in a part of the system may be reduced to a potentially hazardous level due to shutdowns in the system, main breaks, heavy fire demand, high water usage, pumping, storage, or transmission deficiency.

Prevention of Health Hazards (4)

It is recognized by the Ministry that health hazards may develop through proximate locations of watermains and sewers. Adequate protection must be provided to prevent the occurrence of waterborne disease and chemical poisoning due to contaminated ground- water and surface run-off entering the water distribution system.