scope:

General

This Standard covers the manufacture of septic tanks and their associated fittings for the treatment of domestic wastewater only. This range of tanks typically is designed to cater for:

(a) All-waste (Blackwater and Greywater);

(b) Blackwater only;

(c) Greywater (with or without kitchen waste included) only; and

(d) Holding tanks (collection wells) and pump wells.

Septic tanks covered by this Standard are suitable for a flow of domestic wastewater of up to 14,000 litres per week.

Structural design

This Standard provides guidance for consultants and designers of septic tank systems. Structural design provisions included in the document apply to conventional designs installed in standard situations. Specific structural design by a suitably qualified structural engineer, using appropriate design methodologies and relevant Standards, shall be carried out when any of the following conditions apply:

(a) Capacity of the tank exceeds 6000 L;

(b) Tank lid or wall is below ground level;

(c) The internal diameter of the cylindrical tank and the internal width or internal height of a rectangular tank is greater than 1800 mm;

(d) The internal length of a rectangular tank is greater than 2400 mm;

(e) Tank lid plan area is greater than 4.5 m².