Precast Concrete Septic Tanks – Absolute Concrete

Precast Concrete Septic Tanks

Absolute Concrete have made Septic Tanks for many years.

Historically made of plastered layers but modern environmental concerns along with concerns around contamination of in-ground water supplies mean that we now precast the tanks to make a far more impervious and robust structure.


Absolute Concrete have been producing septic tanks for over 30 years.  Historically made in plastered form, now made in the more robust pre-cast format. They are simple, reliable and cost effective solutions for your septic waste. Our precast units hold roughly 4,500 litres and weight close to 4 Tonnes and can be Hi-ab’d straight into a prepared hole.

Septic tanks are manufactured to NZS3107:1997 and are designed to be buried with a maximum of 600mm fill cover.

Precast 4,500 litre Septic Tank

Standard Primary System Septic Tanks work on a trickle in, trickle out basis. They come in both single and dual chamber option. A filter is fitted to ensure most of the solids are retained in the tank and do not clog the effluent field. The dual chamber tank is designed to retain more of the solid matter back in the primary chamber to effectively put less pressure on the filter. Leaving some effluent in the bottom of the second chamber enables faster reactivation after pump-out.

Also available in the 7/30 split Dosing Chamber format, fitted with a dosing siphon to flood the field on each discharge is the preferred option for most waste-water engineers today.

Filters should be inspected and cleaned regularly to ensure they don’t block and back up the system.

These tanks are also ideal for storm-water attenuation, especially on sites where room is restricted.

We also manufacture a range of mini stand alone pump chambers that can be used to convert existing single chamber septic tanks into dosing or pump out systems.

Please call us for more information.