The Ontario Building Code | Connection of Subsoil Drainage Pipe to a Sanitary Drainage System
7.4.5.3. Connection of Subsoil drainage Pipe to a sanitary Drainage System
(1) Except as permitted in Sentence (2), no foundation drain or subsoil drainage pipe shall connect to a sanitary drainage system.
(2) Where a storm drainage system is not available or soil conditions prevent drainage to a culvert or dry well, a foundation drain or subsoil drainage pipe may connect to a sanitary drainage system.
(3) Where a subsoil drainage pipe may be connected to a sanitary drainage system, the connection shall be made on the upstream side of a trapwith a cleanout or a trapped sump.
In Plain Language
Subsoil drainage pipe (used to manage groundwater around a foundation) can only connect to a sanitary drainage system under specific conditions, since subsoil water isn't sewage and mixing the two systems improperly can overload sanitary infrastructure.
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.