Technical Booklet N Drainage·Page 8·7(3)
Septic tank and treatment plant construction requirements
Structures other than cesspools must be of suitable depth with minimum capacity of 2.7 m³, covered or fenced, ventilated if covered with access for inspection, and equipped with filter or treatment facilities for effluent.
Any structure to which paragraph (1) applies other than a cesspool shall be—
(a) of suitable depth;
(b) of adequate size, having in no case a capacity of less than 2.7 m³;
(c) covered or fenced in;
(d) if covered, adequately ventilated and constructed with means of access for the purposes of inspection (including inspection of the inlet and outlet), emptying and cleansing;
and
(e) fitted with filter or other treatment facility for effluent (including subsurface irrigation) or both, sited to comply with the requirements of paragraph (1)(b)(i) and (iii).
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