Aerated water treatment systems often have a maintenance contract signed at the same time the system is installed. Some manufacturers make it clear that their systems require service and maintenance inspections every six months for the warranty to remain valid.

Some local authorities also have set maintenance requirements. For example, Auckland Council requires that all systems in its area are serviced at least every six months.

These inspections should include a check of the condition of filters, pumps and piping and ensure that the chambers are working properly. If there is an alarm in the system, the inspection will check that it is functioning properly.

Inspections will also measure the level of sludge and scum. Aerated systems require sludge to be pumped out every few years, as with septic tanks.

There are often simple maintenance steps that owners can carry out themselves, such as cleaning the outlet filter. The system supplier will provide details.

You may need to contact your service agent if you expect to be away from home for several months, leaving the system unused. This is because the bacteria in the system may have died and need replacing when you return home.