Technical Booklet N Drainage·Page 13·2.9
Branch pipe discharge from upper and ground storeys
Branch pipes from upper storeys must discharge into branch pipes or discharge stacks. Ground storey appliances may discharge into branch pipes, stacks, stub stacks, drains, or gullies, subject to specific conditions for water closets and discharge heights.
The branch pipe from an appliance on a storey above the ground storey should discharge into another branch pipe or a discharge stack. An appliance on the ground storey may discharge into another branch pipe or a discharge stack, a stub stack, a drain or (if the appliance is for washing purposes only) a gully provided that – (a) a branch pipe from a water closet discharges directly to a drain only if the drop is less than 1.5 m (see Diagram 2.2); and (b) a branch pipe discharges to a gully only between the grating and the top level of the water seal.
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