A quick guide to rainwater tanks

Rainwater tanks are a great way to reduce your dependency on mains water if you live in an area where it rains frequently and regularly throughout the year. When plumbed into your home the benefits can be even greater – saving up to 20% of the average in-house water use each year and reducing your water bill.

Where can I use rainwater?

In the South West and Great Southern regions, a 125m2 roof area can collect up to 51,000L of water annually, supplying part of your household’s non-drinking water needs.

While rainwater tanks are great for hand watering your garden, connecting a tank to your toilet or your laundry is where the real water savings can be made. This is because it can be used year-round and not just during the dry months, when you would typically use the stored rainwater water to hand water your garden.

Plumbing your rainwater tank into your home ensures the rainwater is used on a regular basis and the tank captures more rainfall during the year.

What to consider before buying a rainwater tank

Before you decide to invest in a rainwater tank, you should consider the region you live in. The amount of rainfall you get and how often you get it will influence the amount of water you can effectively capture and use.

Rainwater tanks come in various shapes and sizes, so choose a tank that fits your space and is right for your needs. Think about where your tank will go. To keep costs down, you should install your tank close to your house, near existing downpipes.

The best time to install a rainwater tank is when you're building your house. However, no matter when you choose to install a rainwater tank, a licensed plumber can assess your roof catchment size and structure to determine the best location for plumbing into your house.

What size tank do I need?

Smart Approved WaterMark recommend purchasing a tank that holds a minimum of 4 weeks’ supply. So, if you’ll use 1,000L of rainwater each week in the garden, toilet and laundry combined, consider a 4,000L tank. The online tool, tankulator can help you calculate the right size tank to suit your water needs. 

Council approvals & installation

Most local councils require you to submit a building application for approval to install a rainwater tank on your property. Please check with your local council to see if this applies to you. They’ll also be able to advise of any other council-specific requirements for rainwater tank installations.

When it’s all systems go, your rainwater tank, fixtures, pipes and pumps must be installed by a licensed plumber.

Check your eligibility for our waterwise offers

Throughout the year we provide tailored rebates in eligible towns across WA to help you to save water in your home. They include offers for rainwater tank rebates and plumbing services. View current offers and check your eligibility.

Where to find waterwise rainwater products

Using waterwise approved rainwater products will help you use water more efficiently inside and outside your home.

Together with Australia’s water conservation label, Smart Approved WaterMark, our waterwise product endorsement program makes it easy for you to identify these products. When shopping for rainwater products, keep your eye out for the Waterwise and Smart Approved WaterMark logos, or browse recommended products on the Smart Approved WaterMark website.

Need more information on rainwater tanks?

Get in touch with your local council or visit the Healthy WA website to learn more about installing a rainwater tank in your home.