The 1.0m ENDURO. Twelve sizes, 2,000 to 10,000L.

Every standard 1.0m ENDURO, 575mm low profile and Super Duty underground tank is priced on this page, including GST, and you can order it online. Your Promax rep then confirms the tank and arranges delivery, including delivery to site if you want it.

TankGuard tanks are priced on enquiry. Pricing several tanks or a whole subdivision? Send the tank schedule and we will quote the lot.

Tanks of 6,000L or smaller are delivered free to site by hiab anywhere in the Auckland Metro area. Every standard 1.0m ENDURO travels free to your nearest Mainfreight depot in the North Island. Anywhere else in the North Island, your Promax rep arranges delivery to your site and quotes it with your order. Pickup from Promax is also available.

South Island site? See the XPRESS range first.

Yes, but start with the XPRESS. ENDURO is built in the North Island, so South Island freight is quoted with the order. The 1.2m XPRESS is built in the South Island, covers 2,000 to 10,000 litres, and is usually the shorter trip. See the XPRESS range.

Your resource consent or stormwater engineer sets the volume, usually in litres or cubic metres.

If you have that number, go straight to the standard sizes and pick it. If you do not have it yet, send us what you do have and we will tell you what is needed to size it.

Only with the right lid and riser. The standard polyethylene lid supplied with the tank is for garden areas. For a pedestrian or trafficable area the installation guide calls for a steel manhole lid and a Promax adjustable riser, which takes a concrete surround so vehicle loads are carried by the concrete and not the tank.

The guide has installation drawings for residential driveways (vehicles up to 2,500kg) and commercial driveways (vehicles up to 10,000kg). Anything heavier needs an engineer. Tell us what goes over the top and we will confirm the right lid and riser to order with the tank.

The installation guide sets a 45 degree line of influence that has to start at least 1,000mm from the edge of the house foundations, and at least twice the retaining height away from a retaining wall. Leave a minimum of 150mm between the tank and the excavation wall at the narrowest point. The design assumes the site meets the NZS 3604:2011 definition of good ground; if it does not, or the tank cannot sit outside those limits, a chartered professional engineer needs to look at the site.

Washed crushed stone or gravel with angular particles no larger than 13.2mm, or clean naturally rounded gravel no larger than 19mm, with no more than 5% passing a 2.36mm sieve and a dry density of at least 1,500kg per cubic metre. Do not mix the approved backfill with sand or native soil, bring it up to at least the tank crown, place it in lifts of no more than 300mm, and probe it under the full length of the tank and into the ribs so there are no voids.

The Underground Tank Installation Guide covers handling, location, excavation, backfill, anchoring and manholes, with installation drawings for lawn areas, residential driveways (vehicles up to 2,500kg) and commercial driveways (vehicles up to 10,000kg). The Underground Tank Riser Installation Guide is on the same downloads page, and the dimensions and weight of every size are on its product page.

An empty tank in saturated ground wants to lift. Uplift restraint kits hold it down, and they are sized to the tank: on the 1.0 m ENDURO that is one kit per 1,000 litres, so a 5,000 litre tank takes five.

Stated burial depths in the installation guide assume dry ground with no hydraulic loads, so if groundwater is a known issue on your site, say so when you enquire and it goes into the spec.

When the site has a high water table, rocky or heavy soil, flotation risk, or more load over the top than a standard install. It runs 2,000 to 10,000 litres, it is priced online in the full range above, and it is usually specified alongside an uplift restraint kit. Send your site details and we'll confirm whether it applies.

TankGuard suits stormwater detention projects where protecting the controlled discharge outlet from blockage is part of the design. It is built as a separate version of the tank rather than fitted afterwards, so ask us and we will quote the TankGuard version of the size you need.

Pro-rata, from the date of purchase, per the Promax Warranty Terms and Conditions:

• ENDURO underground tanks: 10 years
• Standard underground tanks: 5 years

The warranty covers the tank. Lids, fittings and inlet and outlet connections are excluded. The tank must be registered on promax.co.nz within 30 days of delivery.

A drainlayer, working to the Promax Underground Tank Installation Guide that comes with the tank. Excavation, bedding and backfill all matter on an underground tank, and connecting into the drainage is restricted work in New Zealand, so it has to be done by a registered drainlayer.

Your project location, the application, the required volume, site conditions, consent notes, and any plans or outlet specifications you have. Nothing needs to be finalised before you make contact.