Conventional Septic Tanks
The most common on-site system in New Zealand: a settlement tank discharging by gravity to a soil disposal field.
A conventional septic tank is a sealed chamber, usually concrete or polyethylene, with an inlet tee, an outlet tee or filter, and one or two compartments. Wastewater settles, solids accumulate, and clarified liquid flows out to trenches or a bed.
Its great advantage is simplicity: no power, no moving parts, and decades of service if it is emptied on schedule and the field is protected. Its limitation is that all of the real treatment happens in the soil, so it needs a suitable disposal area and reasonably permeable ground.
Servicing needs
- Sludge and scum measurement every one to two years
- Pump-out typically every three to five years
- Effluent filter cleaning where fitted
- Baffle, tee and lid condition checks
Frequently asked questions
- How do I know if I have a conventional tank?
- No control panel, no alarm, no power supply near the tank and no audible blower usually indicates a gravity septic tank. An inspection will confirm it.
Related guides
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