The Ontario Building Code | Protection from Backflow
7.6.2.3. Protection from backflow
(1) Except as provided in Sentence (3) and Articles 7.6.2.4. to 7.6.2.6., where a backflow preventer is required by this Subsection, the backflow preventer shall be selected, installed and tested in conformance with CSA B64.10, "Selection and installation of Backflow Preventers".
(2) backflow preventers shall be provided in conformance with Sentence 7.2.10.10.(1).
(3) Tank type water closet valves shall be provided with a back-siphonage preventer in conformance with Sentence 7.2.10.10.(2).
In Plain Language
Except as permitted, protection from backflow is required throughout the potable water system, preventing non-potable water from being drawn or pushed back into the drinking water supply.
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.