Base Preparation

Quite often this aspect of your rainwater harvesting system is underestimated. Please remember that every litre of water is one kilogram of weight. So a 3000 litre water tank is 3 tonnes. That equivalent to two normal cars!! This is important when considering the location of your tank and the base you may choose to sit it on.

For example, it is certainly not recommended to put a tank of any size on a veranda, or an area which is high in uncompacted fill and will subside.

Our tanks are suitable to be placed on the following bases 


Concrete slab 

This is the best base for any water tank. We would recommend 100mm 20MPA concrete slab with F72 reinforcing mesh. The slab should be 100mm larger than the water tank all around. Ensure the slab has been cured for 7 – 10 days ready for our Designer Tank team to carry it into position. 

Here is a good step by step video by Mitre 10 on how to lay a small water tank concrete slab


Paver base 

This is a good alternative if its difficult to get concrete to the area you need and can also be faster. You can purchase concrete pavers in various sizes so once you have worked out your tank size, configure the number of pavers and size to suit. You will need to remove any vegetation first, then lay and level 80mm of sand and cement mix (you can purchase these in premixed 20kg bags) and then place your pavers tightly together. Finally, water the pavers and butter up the edges. The moisture in the ground and from the hosing will set the cement and form a strong base


Crusher dust / Sand base 

This can be an easy option but it does have some risks. The sand or crusher dust must be 100mm think and well contained, such as in a treated pine surround or besser blocks. If the sand can escape from around the tank the tank base will fail. Also, you will need to keep a close eye on your tank base to ensure that there isn't any erosion of the base due to water run off.


Tank stand 

A tank stand can be the most costly base solution for your tank. Tank stand must be well engineered to handle the large loads of water and significant footing is required due to the point loads, often more so than a concrete slab. Designer Tanks have a range of smaller tank stands, but for larger solutions you would need to consult  an registered engineer. Finally, some people think they require a stand to be able to get a bucket under the outlet and use gravity…but in reality its cheaper to go for a taller tank and fix a extra tap at knee height.