Care and Maintenance of a Septic Tank | CST Group NZ

Care and Maintenance of a Septic Tank

A septic tank is designed to hold a body of still water in which anaerobic bacteria break down sewage. This forms three layers within the tank as follows;

Septic Tank Maintenance







As sewerage passes through the tank the solid waste floats to the surface where the bacteria act. To maintain optimum bacterial action it is important that this surface layer is not fouled with oils and fats and the system does not become flooded through poor drainage.

As the system works, the top layer will increase in depth while the bacterial waste forms sludge in the bottom. When the combined of these two layers exceeds the depth of the liquid layer your tank requires servicing (about two to three years for an average household). Tanks not serviced beyond this stage become inefficient and the inlet becomes blocked or sludge blocks the disposal field eventually seeping to the ground surface creating a health hazard.
Used in normal quantities the use of washing powder, soap, detergent, drain cleaners, and even small quantities of disinfectants will not harm the system.

The Do’s and Don’ts:

DO – use biodegradable soaps to enable the quick breakdown of wastes and to avoid foaming
DO – clean your tank regularly – every 2-5 years.
DO – clean the filter every 6-12 months if your tank has one
DO – conserve water. E.g. only wash full loads of washing etc.
DO – contact us if you have any questions or enquiries. 0800 11 44 90

DO NOT – use excessive amounts of hard detergents or disinfectants, these kill the bacteria.
DO NOT – allow newspaper to enter the septic tank. The ink kills useful bacteria, and is also highly likely to block the pipework.
DO NOT – overload the tank with food scrapes, fat, cooking oil, sanitary pads, disposable nappies, etc.
DO NOT – grow deep rooting trees or shrubs on or around the septic tank and effluent trench
DO NOT – allow storm water to enter the septic tank or effluent trench

Our comprehensive range of services includes septic tank maintenance, water delivery, precise hydro excavation, thorough CCTV drain inspections, jetting, and more!