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What size tank should I buy?

Published on: Friday, 25th September, 2015

2500 Litre Slimline Tank

Finally … winter is over and spring is here! (thankfully, don’t know about you but we’re sick of this grey weather!) Summer is just around the corner, and although we all enjoy the great weather we do need to think responsibly about our water use over the summer months.

A question we get asked all the time here at Slimline: what is the best size tank for me? There are three main factors which help you make this decision:

  • What size catchment area the tank will serve
  • How much rainfall your area gets
  • What you plan to use the water for.

For example, a household at Cooper Pedy using their tank to run their whole house will need a much larger tank than a household in Cranbourne using their tank only for the occasional garden watering.

To help you out, here is a few figures to give you an idea of what size tank you may need:

  • Melbourne’s average rainfall is around 650mm per year, and of this only around 150mm of rain falls in the summer months.  Of course, different areas of Melbourne are different, so check here for your average annual rainfall or for your local annual rainfall
  • The size of your roof (that will be going into the tank) in square metres multiplied by your rainfall equals the amount of water you can catch.  Eg 50 m2 of roof x 5mm of rain = 250 Litres of water caught in your tank
  • A standard garden hose or sprinkler uses around 9 Litres of water per minute
  • A soaker hose (depending on the size and the pressure it is set at) uses around 2 Litres per minute
  • Flushing a single flush toilet takes average 4.5 litres
  • A washing machine uses around 150 litres depending on the cycle used

As you can see, it is very hard to estimate exactly what size tank your garden needs.  Probably the most common size for a garden tank is a 2000 – 5000 Litre tank, but we would suggest that you work out the room you have and try to fit the biggest tank you can – you can never have too much water!!

Please call us to discuss your needs … 1800 804 901