The Ontario Building Code | Air Gap
7.6.2.9. Air Gap
(1) An air gap shall not be located in a noxious environment.
(2) Every air gap shall be not less than 25 mm high and at least twice the diameter of the opening of the water supply outlet in height.
In Plain Language
An air gap, a physical vertical space between a water outlet and the flood level of a fixture, is required in specific situations as one of the simplest and most reliable backflow prevention methods.
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.