Promax Water Tanks

Promax water tanks are designed for New Zealand homes, farms, lifestyle blocks and commercial sites, with capacities ranging from 450L to 30,000L. Explore our main categories below to quickly find small water tanks, large water tanks, or slimline water tanks to suit your site, storage needs and available space.

Small Water Tanks | <6,000L

11 products

Large Water Tanks | 10,000L+

7 products

Slimline Water Tanks

8 products

Browse Our Full Range Of Water Tanks

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25,000L Water Tank - XPRESS

$3,412.00

30,000L Water Tank - XPRESS

$3,890.00

25,000L Water Tank - ENDURO

$4,226.00

30,000L Water Tank - ENDURO

$5,104.00

2,500L Water Tank - XPRESS

$968.00

3,500L Water Tank - XPRESS

$1,196.00

5,000L Industrial Tank - ENDURO in Mist Green

5,000L Water Tank - ENDURO

$1,925.00

5,000L Water Tank - ENDURO Low Profile

$2,562.00

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Trusted by NZ homeowners, builders and specifiers since 1985.

Why Water Tanks Are Essential in New Zealand

New Zealand's reticulated water supply does not cover every need. On farms and in rural areas, mains water is either unavailable or unreliable. On urban sites, supply from the network is restricted during dry years.

Droughts and Water Restrictions Across NZ

Droughts occur regularly. After two consecutive dry years, Auckland's dams held 25% less water than usual. Councils introduced staged water restrictions: from voluntary reductions to mandatory bans. Your own tank provides an independent source for irrigation, bathrooms, and laundry.

Reliable Water Supply for Farms and Rural Properties

On farms, tanks solve the challenge of stock water supply. A typical setup: a pump delivers water to a tank at a high point on the property, from where it flows by gravity to troughs. For farms without a mains connection or with an unreliable source, this is the only practical solution.

When a water tank is needed:

Property has no connection to reticulated water supply
Council has imposed water use restrictions
Buffer supply needed for a farm, garden, or livestock operation
Site requires an independent source for firefighting or process use
Rainwater storage needed to reduce utility costs

What Your Own Tank Provides

On urban sites, rainwater replaces mains water for irrigation, laundry, and toilets. The tank fills for free every time it rains, reducing your water bill.

Reliable Water Supply for Farms and Rural Use

On farms, the question is different: without your own reserve, there may be no water at all. The cost of lost stock or failed irrigation during a drought far exceeds the cost of a tank.

A water reserve means confidence in tomorrow. When the council imposes restrictions, when a main bursts, when a dry spell drags on, your own tank provides water regardless of external circumstances.

Long-Life Water Tanks Built by Promax

Promax manufactures tanks built to last decades. Warranty up to 20 years: the manufacturer takes responsibility for durability over the full term. The construction requires no maintenance and does not degrade over time.

Material and Construction

All Promax tanks are manufactured from linear low-density polyethylene (LLDPE) by rotational moulding. This produces a seamless, one-piece construction with no welds, bolts, or joints. The material does not react chemically with water, does not rust, and requires no internal lining.

UV-Stabilised, Food-Grade Water Tank Material

The polyethylene contains UV stabilisers that protect the shell from degradation under direct sunlight. Colour is pigmented throughout: scratches do not expose unprotected material. The material complies with AS/NZS 4020 for contact with drinking water and AS/NZS 4766 for liquid storage tanks.

The flexibility of polyethylene provides an advantage in seismic zones: the material absorbs movement and does not crack under impact loading. Promax can supply seismic restraint systems and PS1 documentation for NZBC compliance (available at additional cost, contact us for details).

Seismic Safety

New Zealand is one of the most seismically active countries in the world. Approximately 50 earthquakes of magnitude 5 or greater are recorded each year, two of magnitude 6 or greater, and an average of four of magnitude 7 or greater per decade.

Why Polyethylene Water Tanks Perform The Best

Polyethylene withstands seismic loads better than concrete and fibreglass: the material is flexible, does not crack under impact, and returns to shape. One-piece construction with no welds or joints has no vulnerable points.

For tanks installed in seismic zones or on sites with higher importance levels (IL2, IL3), Promax can supply seismic restraint systems and PS1 documentation for NZBC compliance (available at additional cost, contact us for details).

Slimline tanks include a built-in seismic bracing system. Promax can supply PS1 documentation to confirm NZBC compliance (available at additional cost, contact us for details).

Enduro Series: 450L to 30,000L

The ENDURO series covers capacities from 450L to 30,000L. Corrugated walls provide increased strength and rigidity.

Available capacities: 450L, 1,000L, 2,000L, 3,000L, 4,000L, 5,000L, 10,000L, 25,000L, 30,000L.

ENDURO tanks can be partially buried: small tanks (up to 5,000L) to one-third of the tank height, large tanks (10,000L and above) up to 1 metre.

ENDURO warranty

Tanks up to 5,000L: 5-year pro-rata warranty
Tanks 10,000L and above: 20-year pro-rata warranty

Xpress Series: 2,500L to 30,000L

The XPRESS series covers capacities from 2,500L to 30,000L. The cylindrical shape simplifies installation of level indicators and pumping equipment.

Available capacities: 2,500L, 3,500L, 10,000L, 15,000L, 25,000L, 30,000L.

XPRESS tanks cannot be buried or backfilled. This voids the warranty. For underground installation, Promax has a separate underground tank range.

XPRESS warranty

Tanks up to 5,000L: 5-year pro-rata warranty
Tanks 10,000L and above: 20-year pro-rata warranty