Custom Size Water Tanks

Steel Water Tanks From 500 to 40,000 Litres






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Thousands of Custom Sizes Available

Different sites have different rainwater harvesting challenges.  Sloping blocks might require a series of water tanks at different heights so they will balance properly.  A low set house on a large property might require squat tanks with a large diameter and low inlet height.  Whatever the challenges Select Water Tanks will help find you the perfect solution.

Slimline Water Tanks


Slimlines are perfect for narrow blocks or yards without a lot of space.  They can fit down the side of a garage or shed without stealing too much real estate.

Select Water Tanks can manufacture down to a minimum width of 550mm for very tight spaces.  It’s important to consider the height of a very slim water tank.  As a general rule, the tank should not be more than 3 times as high as its width.


  • Length Increments:  100mm
  • Width Increments:  50mm
  • Height Increments:  76mm (approx)
  • Common Heights:    1255mm, 1560mm, 1860mm, 2350mm.

Round Water Tanks


If you have the space, a round water tank is by far the best value for money. Round water tanks do not require additional reinforcing, as Slimlines do, so they cost less to manufacture.  They are also easy to clean and maintain.

Select Water Tanks can manufacture a round water tank up to almost 40,000 litres.  Measuring 4000mm in diameter x 3100mm high, this tank requires a crane to position.  Alternatively, we can manufacture a tank that you could fit in the back seat of your car.


  • Diameter Increments: 100mm
  • Height Increments:  76mm (approx)
  • Common Heights:  1255mm, 1560mm,1860mm, 2350mm, 2800mm, 3100mm


Jumbo Stainless Slimline

This customer needed 20,000 litres on a long skinny block in Paddington.

Under The Deck

Under deck tanks are perfect for sloping sites.

Commercial Water Tanks

Water tanks for industry with commercial fittings.

Space Saving

Aquaplate Slimline Water Tanks are perfect for wash bays in high traffic areas.

How Do I Know What Size Tank I Need?

There are a few issues you want to be across before you order a custom size water tank:

First, you want to ask yourself how much water you will need.  A good rule of thumb for whole-of-house systems is to aim for a minimum of 45,000 litres.  Complimentary water systems that supply water to toilets and washing machines are typically between 3,000 and 5,000 litres.  Ideally you want to be confident of having at least 12 weeks of water storage for the drier seasons.

The first thing to understand is the relationship between your roof area (catchment) and the amount of rainfall.  Your water tank will collect 1,000 litres for every 10mm of rain that falls on 100 square metres of roof area.

10mm of rain x 100 square metres = 1,000 litres


Some More Tips!

Pay careful attention to the difference between the height of the gutters on your roof and the anticipated height of the tank. This is called the Hydraulic Gap.  Remember that a rain head installed below your gutters will narrow this hydraulic gap.  The ideal hydraulic gap for a ‘charge line’ system is 500mm (other factors can impact on this).

If replacing a water tank take careful measurements of the slab / tank pad.  The tank pad needs to be at least 100mm x 100mm greater than the diameter of the water tank.

Make sure to check the access from the front of your property to the water tank site.

Request a free quote, it’s easy.

What you’ll get.

A phone call or email consultation within 8 business hours.
A free quote on your water tank and rainwater harvesting system.
Expert advice and friendly service at no extra cost.

Prefer to Call Us

Call our rainwater harvesting system specialist to discuss your needs.
Craig Reading has over 15 years experience in the rainwater harvesting industry with a great understanding or water tank design and manufacture, water tank installation, pumps, filtration and system maintenance.  He’s waiting for your call!