Selecting a Rainwater Tank

Rainwater tanks are available in a large variety of shapes, materials and sizes. Choosing the best water tank for your situation will help you to preserve one of our most precious resources and reduce your water bill. There are a number of points to consider when deciding which rainwater tank is going to be right for you.

Tank size and rainfall

The obvious decision you need to consider when purchasing a tank is around the tank size. Questions you may need to ask yourself could include:

  • How often will I be using the rainwater held in my tank?
  • How much rain does the area I live in typically receive?
  • How much space do I have around my home for a tank?
  • Will my tank require any structural support?

Tank location

There are rainwater tanks available for underground installation as well as above-ground installation. The most suitable option for you will depend on your unique situation. Above-ground tanks can be installed alongside your house, or even under your house in some cases.

Tank material

Different tanks are manufactured using different materials, depending on the specific purpose of the tank being considered.


These tanks come with corrosive resistant coatings to prevent rust. There should be at least two metres of plastic pipe between a steel tank and copper, brass or bronze fittings as they can cause corrosion. Galvanised and Zincalume steel can be considered as an alternative, however they are both prone to rusting. Copper and stainless steel can also be considered for specific situations.


Fibreglass tanks are durable and resist corrosion however, they are often more expensive and can expose the stored water to sunlight. Stagnant water exposed to sunlight can allow algae to grow, some forms of which may be toxic for both humans and pets. Ensure you purchase a tank which is manufactured with sufficient pigment to prevent light entering the tank.


These tanks are strong and heavy which means they can be installed underground. New concrete tanks may need to be flushed clean because they can release excess lime leading to a high pH in the water. Some concrete tanks require a lining to be installed.


Plastic tanks respond well to bumps and are non-corrosive. These are often the cheapest tanks. Their advantage is that they are lightweight, easy to transport and are available in a range of colours.