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Rainwater tanks can help you save water, but they must be designed and maintained to achieve water saving benefits long term.

Urban households are generally connected to a central mains water supply for drinking and general household use. In these areas, rainwater can be used to reduce mains water use. It is typically used for:

  • watering your garden/lawn
  • flushing toilets
  • clothes washing (connection to your washing machine).

Many rural communities do not have access to mains drinking water. These communities rely on private supplies, which can include rainwater. Visit the Department of Health’s website for more detailed information on private drinking water supplies.

Choosing a rainwater tank

A licensed plumber or local water tank supplier can advise you about installing a rainwater tank in your home. This includes choosing the best location and tank size for your house, the permits required and regulations that must be followed.

To help get the most out of your rainwater tank, consider discussing the following points with your plumber or tank supplier.

Check out the health, building or council regulations in your local area.

A licensed plumber will be required for some of the work, including the pipes in and out of the tank (for example connecting the gutters to get rainwater in and an overflow pipe for excess water to go to the council stormwater drain).

A licensed plumber is also required if you want to connect the tank to toilets and/or your washing machine.

The tank will be heavy when it fills with water so it must be installed on a strong, level and stable foundation.

Place the tank in a location where you can collect as much rain as possible from your roof.

The planned uses for your rainwater (for example, gardens, toilets or washing machines) will help to determine what size you need.

A typical house in Melbourne will need between 2,000 and 5,000 L.

There are a variety of rainwater tank sizes, materials and colours to match your property and available space.

Your budget and the planned location of the tank will influence the type of tank you need.

A small external pump is generally used for simple residential use but this will depend on your property size and how you use rainwater in your home.

Multistorey houses and properties with significant slopes may require larger pumps.

Maximising the roof area flowing to your tank is the best way to maximise your water savings, regardless of tank size. This may mean connecting as many downpipes as possible.

Connecting as many indoor uses as possible, like the toilet or washing machine, will also help to increase your water savings.

Do your research before you decide and consider getting multiple quotes.

For examples of how to maximise your roof area and water savings, refer to Scenarios 7-10 (p19-22) of the EPA’s Urban stormwater management guidance.

Installing a rainwater tank

We recommend that you hire a licensed plumber who's experienced with rainwater tank installations. You may also need an electrician to provide a safe power supply for your pump and a tradesperson to lay the foundation for your tank.

During installation, it's important to:

  • Check that your roof and guttering are suitable for collecting rainwater. Don't collect rainwater from roofs with lead-based paint or flashing, bitumen-based products, or exposed treated wood.
  • Prevent blockages from overhead trees and vegetation by trimming them or installing gutter guards.
  • Check that your rainwater tank inlet and overflow are mosquito-proof proof, and ensure there are no other entry points for insects.
  • Use a first-flush device. This is a simple and effective way of only letting the cleanest water into your tank.
  • Install a mains switching device to supply drinking water when the tank is empty.
  • Consider adding energy-efficient accessories like a pressure tank to your pump. These reduce the number of times your pump runs, saving energy and maximising the pump's life.

The Victorian Building Authority also provides a rainwater tank installation checklist, which can help to check if your installation has been completed correctly.

Maintaining your rainwater tank

One of the benefits of collecting rainwater is that it can be a straightforward and low-maintenance way to save money on your bills.

However, rainwater tanks and the connected system still require regular maintenance to keep them working well.

A basic understanding of how your tank operates, checking that all the parts are working correctly and doing some basic maintenance activities will help keep your tank in top condition.

There are a few things you can do to confirm that your system is working:

1. Check for rainwater in the tank

Look inside the tank or knock on the side and listen for water. If there hasn’t been much rain recently, the water level might be low. If it has rained recently and your tank is empty, there may be a leak or blockage at the inlet. If the tank is consistently full after an extended dry period, then check your pump is working correctly.

2. Check if your pump and mains switching device is plugged in and turned on

If your rainwater system uses a pump, you'll find it inside or outside your tank. Check that the water connections are on.

You need to check your pump and mains switching device to ensure they work. Sometimes, they can fail after an electrical trip or blackout and will need to be reset manually.

3. Check if you're using rainwater

Turn on your garden tap, flush a toilet or turn on your washing machine – whatever is connected to your tank. You should hear your pump starting up. If you don’t have a pump, check that the water is flowing.

If you’re unsure if your toilets or washing machine are connected to your tank, contact a plumber to arrange an inspection.

Your rainwater tank requires regular maintenance to do its job properly and maximise water savings in your home. Here are some simple ways for you to make sure your system is working:

1. Check and clean your gutters, screens and downpipes

Your gutter downpipes carry water from your roof into your tank. If they fill with leaves or debris, it can affect the quality of your rainwater or even block the flow completely.

Some ways to prevent blockages, increase flow and improve the water quality of your system include:

  • cutting back overhanging branches or vegetation
  • cleaning your gutters, screens and downpipes
  • removing leaves and debris from your roof
  • installing a gutter guard and downpipe screen.

2. Check your first flush device and flow restrictor

When it starts to rain, the rain will wash dirt and leaf litter from your roof and gutters into your rainwater system.

Some systems have a first flush device that diverts the first flow of dirty rainwater to a separate chamber, stopping it from entering your tank. This chamber will slowly empty the dirty water through a flow restrictor that can block easily.

It’s important to clean your first flush device and flow restrictor, at least after each heavy rainfall event, to make sure that the chamber is clear of blockages.

3. Check your tank inlet screen

The tank inlet screen stops leaves, debris and mosquitos from entering your rainwater tank.

Clean the screen regularly by removing any leaves and debris to prevent blockages and increase rainwater flow into your tank. Some screens can be removed and rinsed with a hose.

If your screen has holes in it, replace it as soon as possible.

If you have completed the suggested checks and have come across an issue or are unsure how to check your rainwater system, you can contact a local licensed plumber to inspect your system and repair any issues.

Page last updated: 08/09/23