The Ontario Building Code | Separate Services
18.104.22.168. Separate services
(2) An ancillary building on the same property as the main building may be served by the same service.
(3) Water service pipes or building sewers serving buildings located on the same property may connect into a private water supply or a private sewer conforming to Article 22.214.171.124.
(4) No plumbing serving a dwelling unitshall be installed in or under another unit of the buildingunless the piping is located in a tunnel, pipe corridor, common basement or parking garage, so that the piping is accessible for servicing and maintenance throughout its length without encroachment on any private living space, but this Sentence does not prevent plumbing serving a unit located above another unit from being installed in or under the lower unit.