Rainwater tankRAINWATER TANKS

Rainwater is water that is collected from the roof run-off during rainfall. It can be collected in a tank to use in the home for non-drinking purposes, such as toilet flushing, garden irrigation or washing clothes.

Why use rainwater?

The best reason for using rainwater is that it is free and, if not captured in a tank, it is a vital resource that literally goes down the drain.  Rainwater tanks are an increasingly common feature in gardens around Australia. Despite the initial cost, installing a rainwater tank can save you money by reducing your water bill in the long-term, and help save the environment.

If you're building a new home, installing a 2000 litre or more rainwater tank for toilet flushing is one of the options to achieve the minimum regulatory requirements of the 5 Star standard. The Victorian Government offers rebates of $150 on the purchase of rainwater tanks (600 litre minimum) that are installed by a licensed plumbing practitioner.

What do I need to know about rainwater tanks?

As demand for rainwater tanks increases, manufacturers have responded with a wide range of shapes, sizes and colours in a range of materials. You can ask a licensed plumbing practitioner about rainwater tanks, or visit a garden centre or specialist water tank supplier.

Choose a tank that suits your needs and actually fits in your garden. Installation is best carried out by a licensed plumbing practitioner - this is required if you are connecting to your home for toilet flushing or other non-drinking use. Some councils may require a planning permit to install a rainwater tank or they may have restrictions on the maximum size or location of the tank. Ensure that any product installed is compliant with Australian Standards and other relevant regulations.

Did you know?

  • Toilets use about 14% of drinking quality water in the home
  • Washing machines use about 16% throughout the year
  • Gardens use about 20% of drinking water, mostly in the summer in metropolitan areas.


 What size rainwater tank will I need?

You should choose a suitably sized tank  based on your water requirements, how much room you have and how much you can afford. Larger tanks may be more appropriate for gardens and pools. Smaller tanks suit constant demand, such as toilets and the laundry. Talk to a licensed plumbing practitioner about the catchment area of your roof, so you choose an appropriate size tank.

Generally, your tank should hold a minimum of four weeks supply of water based on your level of usage. This will mean that the tank will only be empty through extended dry periods. It is easy to calculate the amount of rainwater you will collect: each square metre of roof area collects one litre of water for every one millimetre of rainfall.

What material should my rainwater tank be made from?

Tanks are available in a wide range of materials, shapes and sizes. Polyethylene or plastic tanks are often the cheapest to buy. They are non-corrosive, are easy to transport and come in a range of colours. Tanks made from corrugated steel, coated with corrosion resistant coatings, zincalume or have been galvanised are also popular for above ground use. Tanks are also made from fibreglass and concrete.

Where should my rainwater tank be located?

Most rainwater tanks are above ground. But to save space, it is possible to install concrete or specially reinforced polyethylene tanks underground or "bladders" under houses. Where space is at a premium, it is possible to buy slimline tanks that can be installed under eaves or along fences.

For efficiency and to reduce installation costs, you should locate your rainwater tank  close to the house near already existing downpipes and stormwater drains for overflow. Consider your neighbours when installing a tank, especially if your homes are close together.

How do I install a rainwater tank?

It is best to have a licensed plumbing practitioner install your rainwater tank - remember, a licensed plumbing practitioner is required by law wherever a tank is connected to the mains water supply such as a tank for a toilet system. They are also required where you may connect your gutters to your tank and to install an overflow to stormwater. A licensed plumbing practitioner will provide a certificate of compliance.

Most tank manufacturers can organise a licensed plumbing practitioner to provide installation for you. Some tank installations (particularly for large tanks) may require a building permit. The tank manufacturer's instructions will guide you on installation, particularly on matters such as levelling and preparation of the site for the tank, but it is a good idea to consult a licensed plumbing practitioner about the fall of your gutters and the best location for the tank to maximise the catchment area. 
 
What accessories will I need?

It 's important to ensure that debris and contaminants don't get into the tank and become a breeding ground for insects, such as mosquitoes. This means installing a 'first flush' system and leaf-shedding gutter protection as well as one mosquito-proof mesh.

Unless you can locate your tank on a high enough point on your block to gravity feed the garden, you will need a pump. Choose one that suits your purposes, particularly if you are using the water within your home. Pumps come in all sizes, speak to a pump specialist about your needs.

Where rainwater is used for toilet flushing or other household uses, you are required by law to install a backflow device to prevent tank water from entering the mains system. You will need electricity nearby to power a pump. Be mindful of neighbours with the level of pump noise.