Deciding your Tank Size

There are three main factors to choosing your ideal tank size and these are listed below. After reading through these considerations the team at Designer Tanks can further discuss your unique situation and together we can determine your ideal tank size.

Access to get your tank in

One of the very first considerations is the room you have available to have the tank delivered to the desired position. You may have a large area out the back of your house for a tank but remember it has to delivered to that position. Measure spacing between walls and fences and the like. You may have to take a slightly smaller tank to be able to simply be able to physically get it in.

Space available

First thing you need to do is work out how much space you want to allocate to your water tank. This is more applicable to the residential situation, where you may be looking at a slimline on the side of your house or a small round in your back yard. For example you could measure the distance from your hot water heater to your laundry door, then check width so you can still get the lawn mower past…..this would be your physical size limitation. Then discover how much water you can hold in this space using our size-a-tank feature. 

Roof area your harvesting

The size of the roof area you will be harvesting will determine how much water you can catch. If you have a tank too large you may never fill it and you have spent more than you should on a tank. If the roof area is large and you choose a small tank then it will fill in first hour of rain and the rest is wasted to stormwater. A good rule of thumb is your tank should fill with no more than 100mm of rain otherwise it is too big for purpose. See how much water I can catch section to work out how much water you will be catching 


Many people do not realise water usage statistics. A garden hose typically uses 1000 litres of water per hour. So a 3000 litre water tank will provide on average 3 hours of hand watering. A toilet flush on a water efficient toilet is 6 litres. Use our size-a-tank to understand more about water usage. Make sure your tank meets your expectations by sizing it correctly. A good rule of thumb is your tank should provide 70% of your water needs.