The Ontario Building Code | Required Check Valve
7.2.11.4. Required Check Valve
(1) Where a water service pipe is supplied with water by more than one drinking water system, a check valve shall be installed at each connection with a drinking water system.
(2) Where a fire service main is supplied with water by more than one source, a check valveshall be installed at each connection with a source of water.
Section 7.3. Piping
7.3.1. application
In Plain Language
Where a water service pipe can be fed by more than one drinking water system, a check valve is required to stop water from flowing backward between the two systems and cross-contaminating them.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.