ENDURO Super Duty Underground Tank 4,000 Ltr 1.0m

This is the Future of Underground Tanks.  

The Promax ENDURO Super Duty Underground Tank is the first, and only, tank in NZ to be certified to the latest standards AS/NZS4766:2020. The new, more rectangular shape of the ENDURO Super Duty Underground Tank brings a major advantage to the market by reducing excavation and backfill requirements, saving time and money.   

Distinctive Benefits:  

  • Unique shape reduces excavation and backfill <20%
  • Certified to AS/NZS 4766:2020
  • 10 Year Warranty
  • Traffic rated for vehicles <10000 kg
  • Multiple Inlet/Outlet panels

Additional freight charges will apply to South Island orders.

Please note: We recently completed an update of our product codes and descriptions. New codes are effective from 1 June 2022. For reference only, the old code for this product is: PMXUS040001.0


Code Description Capacity(L) Length(mm) Width(mm) Height(mm) Weight(kg) Manhole Dia(mm)
US1004000 ENDURO Super Duty Underground Tank 4,000 Ltr 1.0m 4000 4115 1250 1000 330 600

A Promax detention tank and a Promax retention tank are not the same. Sure, they look the same, and indeed, they are both stormwater tanks. But the way they are set up makes them very different. This guide will explain that difference and show you why the words “detention” and retention” are not interchangeable.

The stronger your water tank, the more peace of mind it will give you. It will be better able to withstand the elements at their most extreme and act as a reliable water source for many years. At the same time, you want a water tank that is relatively easy to install. You'll be pleased to know Promax plastic water tanks are incredibly robust and durable but light enough to make the installation process straightforward.

Potential customers often ask us, “What size water storage tank do I need?” At first glance, it might look like one question with a range of complex answers. However, at Promax, we prefer to explain things in simple terms, so we will sum it up in one response: buy the biggest tank possible. In our experience, no one has ever complained that their water tank is too big.

Extra capacity means more water, and we know our customers always find a way to use it. A prime example is in our increasingly drought-stricken regions, where people can access the rainwater they’ve collected in their storage tanks and keep their lawns and gardens alive through frequent watering. There is no such thing as too much water in dry areas, and therefore, no such thing as too much tank volume. Read more here.

When discussing the respective merits of plastic water storage tanks and their concrete counterparts, there are no prizes for guessing where our loyalties lie. Promax is New Zealand's premier manufacturer of superior polyethylene water storage and transport products. Our plastic water tanks combine several significant advantages that make them the smartest choice for residential or rural settings. Read more here. 

Yes! Promax Underground tanks are vehicular traffic approved.  

We recommend using a registered plumber or drainlayer to install your water tanks. Visit our recommended installers page to find one in your area. If you wish to install yourself, we recommend you follow the guidelines provided in the following resources:

At Promax, we pride ourselves on making things easy for you. This includes helping you understand how council consents work. Our team is familiar with the processes surrounding consents, and wherever possible, we'll assist you based on our knowledge of these requirements. Read more here.


We offer a range of speedy shipping options, including North and South Island delivery trucks constantly on the road to ensure your tank gets to you as quickly as possible, and in top condition. Whatever it takes to maximise your storage and minimise your wait.

Click here to see our current lead times 

The short answer is that polyethylene tanks are safe in every department. If you have any doubts about the safety of polyethylene water storage tanks, this article should dispel them.

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