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.
The strongest plastic tank made in New Zealand
Of all the New Zealand-made plastic water tanks on the market, there's nothing stronger than the Promax corrugated ENDURO tank. This is no idle boast. We have engineering on our side. The continuous sidewall corrugation and one-piece moulded construction with a heavy ribbed dome give this tank its unique strength. One-piece moulding matters as much as the corrugation does: there are no seams and no joins, which means there is no line for the tank to fail along. What is left is a single shell whose shape is doing the structural work.
The engineering: why corrugation works
You can liken it to a flat sheet of iron. As soon as you mould it with a profile or put a rip through it, the material becomes more rigid and can sustain increased pressure from both sides. The same principle applies to this tank. The grooves make the Promax ENDURO water tank stand alone with its unrivalled strength and associated benefits. This is also why strength here is not a matter of making the wall thicker. It is a matter of shape, which is what allows the tank to stay light enough for one person to move into position. The same logic separates it from the smooth-walled range, as set out in ENDURO vs XPRESS.
What that strength unlocks
The benefits of the corrugated sidewall are practical, and they show up as things you are permitted to do with the tank rather than as numbers on a datasheet:
- The easiest poly tank to hide, the ENDURO can be buried up to one metre into the ground
- The safest poly tank when buried, you can back-fill against the side wall
- Peace of mind, after submerging and back-filling ENDURO still has a full guarantee of 20 years
- Strong enough for hillside installation, allowing for many more site opportunities
- Specify under decks and homes, increased opportunities for architects and developers
- Proven earthquake strength, with an engineered earthquake restraint system available
- High wind zone installations, with many proven methods New Zealand-wide
- Industrial grade tanks, allowing for large welded spigot inlet and outlet penetrations
- Helicopter installation lifting eyes, so remote installations are easily achievable
Buried, back-filled and still guaranteed
Two of those points are worth reading together. The ENDURO can be buried up to one metre into the ground, and you can back-fill against the side wall. Backfill is the test that sorts tanks out, because an empty tank with soil pressing in from outside is loaded in the opposite direction to the one it spends its life resisting. After submerging and back-filling, ENDURO still carries its full guarantee of 20 years. That is the detail that turns a claim about strength into something you can rely on at the point you specify it, rather than something you find out about later.
More sites become possible
These benefits open up a world of possibilities. Designers, engineers and architects can now explore a broader range of solutions for residential, commercial, industrial and rural applications. A tank that can go on a hillside, under a deck, under a house, into a high wind zone, or into a spot only a helicopter can reach, is a tank that has stopped dictating the design. The site stops being a list of constraints and becomes a set of options, which on a difficult property is worth more than any single specification figure. An engineered seismic restraint is available where the site calls for it.
Earthquakes as a real-world test
Recent earthquakes have provided real-life demonstrations of Promax tanks' strength, while highlighting the limitations of other materials. This is what catapults ENDURO tanks well ahead of different designs. Following the Kaikoura earthquake of 2016, Promax replaced damaged concrete tanks in the Marlborough settlement of Ward. That was a remote installation, and it shows what minimal weight actually buys you: a tank you can get to a site that a heavy one cannot reach. Strength that only exists on a test rig is of no use in Ward. Strength you can fly in is a different proposition.
What this does to the concrete argument
The combination of minimal weight, flexibility and robustness is seriously eroding the concrete water tank market, and demolishing the myth that you should always use concrete for strength. The Ward job makes the point more plainly than an argument does: the concrete tanks were the ones that had to be replaced. If you are weighing the two materials against each other, the useful questions are which one survives the event, and which one you can actually get onto your site. We cover this in more depth in the truth about concrete tanks and in concrete or plastic.
Talk to Promax
Like what you've just read? For further information on the strongest plastic water tanks in New Zealand, or for a project evaluation, contact Promax. Call 0800 77 66 29 or get in touch with the team. If your site is the difficult kind, a hillside, a tight boundary, a high wind zone, or somewhere a truck simply cannot reach, that is the conversation worth having before anything gets specified.