Septic Tanks & Wastewater

Promax septic tanks from 2,000L to 5,000L in ENDURO and XPRESS series. Single stage filtered system with Taylex outlet filter. Made from polyethylene to AS/NZS 1546 (on-site domestic wastewater treatment). ENDURO: rectangular shape, shallower excavation, 5-year pro-rata warranty. XPRESS: cylindrical shape, 5-year pro-rata warranty. Made in New Zealand.
ENDURO available on the North Island (Kerikeri). XPRESS available on the South Island (Rangiora).

Filter

5,000L Septic Tank 1.2m Dia - XPRESS

$5,011.00

4,000L Septic Tank 1.2m Dia - XPRESS

$4,362.00

3,000L Septic Tank 1.2m Dia - XPRESS

$3,806.00

2,000L Septic Tank 1.2m Dia - XPRESS

$2,971.00

5,000L Septic Tank 1.0m Dia - ENDURO

$5,011.00

4,000L Septic Tank 1.0m Dia - ENDURO

$4,362.00

3,000L Septic Tank 1.0m Dia - ENDURO

$3,806.00

2,000L Septic Tank 1.0m Dia - ENDURO

$2,971.00

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Why You Need a Septic Tank

Any rural property without a connection to municipal sewerage needs an on-site wastewater treatment system. In New Zealand this applies to farms, lifestyle blocks, and remote communities. A septic tank receives wastewater from the house, separates solids from liquid, and discharges treated effluent to a disposal field.

Regional councils regulate septic tank installation. Building consent and resource consent are typically required before installation. The tank must comply with AS/NZS 1546.

Plastic septic tanks have replaced concrete as the standard for new installations. Polyethylene is lighter than concrete, does not crack with ground movement, does not corrode, and does not deteriorate. Delivery and installation are simpler and more affordable.

When you need a septic tank:

Rural property without a connection to municipal sewerage
New development on rural or semi-rural land
Replacing an old concrete or fibre cement septic tank
Sewage tank for a bach, holiday home, or secondary dwelling
AS/NZS 1546 compliance required for building consent

What a Promax Septic Tank Gives You

Promax septic tanks are made from polyethylene. Heavy-duty one-piece ribbed construction with no welded seams or joints. Polyethylene does not corrode or deteriorate in the acidic environment of wastewater.

Single stage filtered design: wastewater enters the tank, solids settle, the Taylex outlet filter captures floating particles, and treated effluent exits to the disposal field. Fully plumbed internals to the outlets. Easy installation through 100 mm inlet and outlet.

The construction is engineered for underground installation. The heavy-duty ribbed shell is designed and fully tested to withstand soil pressure and groundwater at depth.

ENDURO vs XPRESS: Which Series

ENDURO (North Island). Rectangular shape, 1.0 m diameter. Heavy-duty ribbed construction engineered by geotechnical engineers. The rectangular shape reduces excavation and backfill volume, saving time and money. Manufactured at the Kerikeri factory.

ENDURO warranty: 5 years, pro-rata.

XPRESS (South Island). Cylindrical shape, 1.2 m diameter. Heavy-duty ribbed construction. Manufactured at the Rangiora factory.

XPRESS warranty: 5 years, pro-rata.

The choice of series depends on the island: ENDURO for the North, XPRESS for the South. Both series are manufactured to AS/NZS 1546 and fully tested.

What Capacity to Choose

Range from 2,000L to 5,000L. The exact volume depends on the number of occupants and regional council requirements. Contact Promax for technical support with volume selection.

2,000L: for a smaller dwelling with standard domestic use.
3,000L: a mid-range option for standard domestic use or higher water consumption.
4,000L: for larger properties or properties with a secondary dwelling.
5,000L: the maximum volume in the range. For larger households or where increased capacity is needed.

Both series (ENDURO and XPRESS) are available in all four volumes.

Installation

Promax septic tanks are installed underground. A typical septic tank installation includes:

1. Obtaining building consent and resource consent from the regional council

2. Preparing the excavation to specification

3. Connecting inlet and outlet pipes

4. Setting up the disposal field

5. Council inspection

Promax recommends engaging a qualified installer. Incorrect installation may void the warranty.

For rural properties, consider the distance to water sources, soil type, and site gradient. These factors affect the size of the disposal field and the choice of tank.

Maintenance

A septic tank requires minimal maintenance, but regular checks extend its service life. Desludging is recommended every 3 to 5 years depending on the number of occupants and usage intensity. The Taylex filter should be checked annually and cleaned or replaced when blocked. Signs that maintenance is needed: slow drains, unpleasant odour, standing water on the disposal field.

A polyethylene tank does not need internal corrosion protection. The acidic wastewater environment does not affect polyethylene. The tank does not crack from seasonal ground movement, unlike concrete and fibre cement alternatives.