Household septic systems guidelines
For a 4 bedroom and 2 bathroom dwelling, typical of many family homes, a commonly used eptic system comprises of 1 x 1520mm septic tank, 1 x 1220mm septic tank and 2 x 9 metre precast concrete leach drains, Drains with a maximum cover of 400mm from the lids to finished ground level, connected via a diverter box.
OR
1 x 3,200 litre baffled modular Polyethylene Septic Tank and 2 x 11m
Polyethylene Leach Drains with a maximum cover of 400mm from the lids to finished ground level, connected via a diverter box.
If you are designing a system for a home you should note that this applies to the following site-specific criteria being met:
1. Ground water table minimum of 2200mm from natural ground level; Leach drains to have a 1:200 fall from the inlet
2. Sandy soils;
3. Site not subject to inundation of flood waters; and
4. Leach drain area is a minimum 30 metres to any bore, well, stream or any underground source of water.
OTHER STANDARD CONDITIONS which should be noted
5. Leach drains to be at least 1.8m from any structure or boundary and septic tanks to be at least 1.2m from any structure or boundary.
6. Leach drains to be 3.6 metres apart from side of drain to the side of the other drain
7. A distance of 1 metre between septic tanks is to be complied with