Technical Booklet N Drainage·Page 7·81
Underground foul drainage requirements
Underground foul drainage systems must be properly sized, constructed, watertight, and ventilated to safely convey foul water to a sewer or treatment structure, with accessible points for maintenance.
Underground foul drainage shall—
(a) consist of pipes and fittings—
(i) of such size, layout, construction and watertightness; and
(ii) with sufficient ventilation,
to ensure the hygienic conveyance of foul water to a sewer, cesspool, septic tank or similar structure; and
(b) have such means of access as is necessary to facilitate the clearance of blockages.
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