PART 7 — PLUMBINGUpdated for the 2024 Ontario Building Code
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7.4.9.2.Serving Water Closets
(1) Drainage pipes that serve a water closet shall be not less than NPS 3.
(2) Branch and building drains downstream of the third water-closet fixture drain connection shall be not less than
NPS 4.
(3) Stacks that serve more than 6 water closets shall be not less than NPS 4.
(4) Discharge pipes serving a macerating toilet system shall be not less than NPS ¾.
(5) No vertical leg of the drainage pipe from a water closet or other fixture that has an integral siphonic flushing action
shall exceed 1 000 mm.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.