(See Note A-7.4.6.4.)
(1)
Except as permitted in Sentence (2), a backwater valve that would prevent free circulation of air shall not be installed in a building drain or in a building sewer.
(2)
A backwater valve may be installed in a building drain provided that,
(a)
it is a “normally open” design conforming to,
(i)
CAN/CSA-B70, “Cast Iron Soil Pipe, Fittings, and Means of Joining”,
(ii)
CAN/CSA-B181.1, “Acrylonitrile-Butadiene-Styrene (ABS) Drain, Waste, and Vent Pipe and Pipe Fittings”,
(iii)
CAN/CSA-B181.2, “Polyvinylchloride (PVC) and Chlorinated Polyvinylchloride (CPVC) Drain, Waste, and Vent Pipe and Pipe Fittings”, or
(iv)
CAN/CSA-B182.1, “Plastic Drain and Sewer Pipe and Pipe Fittings”, and
(b)
it does not serve more than one dwelling unit.
(3)
Except as provided in Sentences (4) and (5), where a building drain or a branch may be subject to backflow,
(a)
a backwater valve shall be installed on every fixture drain connected to it when the fixture is located below the level of the adjoining street, or
(b)
a backwater valve shall be installed to protect fixtures which are below the upstream sanitary manhole cover when a residential building is served by a public sanitary sewer.
(4)
Where more than one fixture is located on a storey and all are connected to the same branch, the backwater valve may be installed on the branch.
(5)
A subsoil drainage pipe that drains into a sanitary drainage system that is subject to surcharge shall be connected in such a manner that sewage cannot back up into the subsoil drainage pipe.