Information icon

Northland is at COVID-19 ORANGE setting. Get information about our services during the protection framework settings.

Arrow icon

Septic tanks

If you live in the country, coastal area or in a small rural town, your household effluent (toilet, shower, kitchen and laundry wastewater) probably drains into an on-site treatment system, and from there into the ground somewhere in your backyard.

The standard on-site household effluent system has two parts – treatment and disposal.  Treatment systems commonly used for household effluent include:

  • Septic tanks; and
  • A group of treatment plants known as Aerated Wastewater Treatment Systems (AWTS).

Treatment plants that use sand and textile filters to provide advanced treatment of effluent are also becoming increasingly popular.

When effluent leaves a treatment system it is only partially treated. Final treatment is carried out by the bacteria that are in the soil below the effluent disposal system. The main purpose of the disposal system is to keep the effluent in the soil within the disposal area so this final treatment happens. A variety of disposal systems are available, with each being designed to suit different site conditions and soil types.

The correct operation and continued maintenance of your on-site system is very important. If neglected, they can pollute groundwater and streams, put you and your neighbours’ health at risk, and they are expensive to fix.

This book outlines the way some of these systems work and what is required to keep them operating effectively.

How to look after your effluent treatment and disposal system

We have produced a guide on how some of these systems work and what is required to keep them operating effectively.

View our online guide to household sewerage systems

View all waste publications produced by us