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AQUAPLATE® Steel in Rainwater Tanks

AQUAPLATE® Steel in Rainwater Tanks

In our last article, we compared Poly Water Tanks with AQUAPLATE® Steel Tanks. In this article we look further into the features of AQUAPLATE® steel in rainwater tanks.

History of AQUAPLATE® Steel

Until recent decades, the most common material for rainwater tanks seen in the Australian outback were corrugated steel tanks. These tanks were often galvanised, which is a process where a protective zinc alloy is applied to iron in order to provide an electrochemical protection against rust and corrosion.

Prior to the 1970’s many steel roofs were largely galvanised. Then a Chicago-based company, Lithostrip Corporation and Pre Finish Metals, discovered a way to successfully bond paint to a galvanised base.

John Lysaght brought the technology into Australia and invested much time and effort getting the process right. This resulted in COLORBOND® steel being rolled out of a Wollongong manufacturing facility for the first time in 1966.

BHP Steel (now BlueScope Steel) bought half of Lysaght’s company in 1969, and by 1988 John Lysaght (Australia) was a wholly owned subsidiary of BHP. Today BlueScope Steel are also known for selling ZINCALUME® Steel which was developed in 1976 and possessed a higher level of corrosion resistance.

Sometime later, BlueScope developed AQUAPLATE® Steel specifically for the storage of drinking water. This steel is made from a base comprised of galvanised steel that is laminated with food-grade polymer film on the inside.

About AQUAPLATE® Steel

While AQUAPLATE® steel is well known in its pre-painted COLORBOND® steel form, it is actually available in painted and unpainted forms:

  1. painted or laminated exterior – ZINCALUME® steel (ZINCFORM® G300S) hot-dip coated in 275g/m2 zinc (Z275)
  2. unpainted exterior – ZINCALUME® steel (G300S) hot-dip coated in 450g/m2 zinc (Z450).

What makes AQUAPLATE® steel specifically AQUAPLATE® is its interior laminated coating of food-grade polyethylene. This is a very thin layer a poly applied during fabrication being only 0.2mm thick (about one quarter the thickness of a credit card).

When COLORBOND® steel is referred to in water tanks, what is often meant is a pre-painted AQUAPLATE® steel product. The same technology used for bonding paint to steel in a COLORBOND® steel sheet is used to manufacture a painted form of AQUAPLATE® steel.

AQUAPLATE® steel is the only product for application in water tanks. Provided the coating is not damaged during the tank manufacturing process, seams are correctly formed and sealed and it is carefully installed, an AQUAPLATE® steel water tank will last many years.

BlueScope Steel provides a conditional perforation warranty of up to 20 years for water tank lids and walls only. This warranty is also extended to water tank bases where the tank is made with double-sided AQUAPLATE® steel (polymer film on both sides) from the date of installation.

Using AQUAPLATE® Steel Water Tanks

Always examine water tank warranties closely, as often such reveal the weaknesses in material, and often detail specific installation instructions which may void your warranty if not followed. Keep the following in mind with an AQUAPLATE® steel water tank:


  • discard the first fill of water to ensure roofs, gutters, tanks and pipes are clean.
  • install anodised aluminium mesh inlet strainers above the water level.
  • install gauze filters on all outlets and overflows to keep out mosquitoes.
  • install the tank away from trees that may drop leaves and clog the strainer.


  • allow tank overflow to run down the exterior tank wall.
  • enter the tank unless necessary. The polymer lining can easily be damaged by tools, ladders and footwear. If entry is required, use rubber soled shoes, rubber ladder footings and great care.
  • collect water from lead, copper, or copper treated timber.
  • store water over 65°C.
  • expose the polymer lining to prolonged contact with alkalis, mineral acids, petrol, kerosene, mineral turps, alcohol or water solutions of inorganic compounds.
  • permit any contact with low organic weight organic acids (acetic, lactic, formic, stearic), aromatic hydrocarbons (toluene), chlorinated hydrocarbons (111 tricholroethane), ketones (methyl ethyl ketone) or esters (cellusolve acetate).

For an in-depth comparison of AQUAPLATE® steel water tanks versus poly water tanks, read Water Tanks Compared – Poly Tanks versus AQUAPLATE® Steel Tanks.