Rainwater harvesting at home: what the system needs and where the rules start
Watering the garden from a tank is simple. Plumbing tank water into the house is where backup supply, cross-connection and testing begin.
Rainwater harvesting means catching roof runoff, storing it in a tank and using it on site. For most Australian households the question is not whether it works. It is what you will use the water for, because that decides how much equipment and how much licensed work you need.
Garden and laundry use is the simple end. Plumbing tank water into the house is the point where rules, backup supply and testing start to matter.
What does a rainwater harvesting set-up include?
Every system has the same five parts. Some are more important than they look.
- Catchment: the roof and the gutters that feed the tank.
- First flush and screening: leaf screens and a device that diverts the dirtiest first runoff.
- The tank: sized to your roof and your use. See what size rainwater tank you need.
- A pump if you want pressure. See our guides to tank pumps and pressure pumps.
- An overflow path that sends surplus somewhere safe. A full tank with no clear overflow causes damage, as we explain in water tank overflow.
Is it worth doing for the garden only?
Often, yes. Garden watering needs no treatment and no connection to the house plumbing, so it is the cheapest way to get value from a tank. A tank, a pump if you want pressure, and a hose or drip line is the whole system.
Check local watering rules and any council requirement for tanks before you buy. Those differ by state and by council, and we do not list them here.
What changes when you plumb tank water into the house?
Plenty. Using rainwater for toilets or the washing machine means a changeover or backup arrangement so the fixture never runs dry, plus clear labelling so nobody mistakes the pipes. Connecting a tank to household plumbing is licensed plumbing work in Australia, and the rules differ by state and territory.
The main hazard is cross-connection. Tank water must never be able to flow back into the mains supply. That is why the work needs a licensed plumber and why we do not describe the connection steps.
Can you drink the water?
Do not assume so. Roof runoff can carry bird droppings, leaf matter and whatever has settled on the roof, and a tank can grow bacteria. If you want to drink it, have the water tested by an accredited (NATA) laboratory, and never treat the result of a home test kit as a clearance. Our page on whether tank water is safe to drink covers what to ask for.
If anyone in the house is very young, elderly or has a weakened immune system, ask your state health authority for guidance before drinking tank water at all.
How far can you take this yourself?
Choosing a spot, cleaning gutters and screens, checking the overflow and watering the garden from the tank are all yours. So is booking a laboratory test.
This far, and no further. Connecting a tank or pump to the house plumbing, adding a mains backup or touching anything near the electrical supply of a pump is work for a licensed plumber or electrician. Licensing and tank rules are set by each state and territory, so ask your plumbing regulator and your council what applies where you live.
Garden only, laundry and toilets, or drinking: what each needs
| Use | What you need | Licensed work? |
|---|---|---|
| Garden watering | A tank, a pump if you want pressure, and a hose or drip line | No connection to the house plumbing |
| Laundry and toilets | A mains changeover or backup, clear pipe labelling and backflow protection | Yes, a licensed plumber |
| Drinking | A laboratory test and possible treatment | Plumbing connection is licensed; testing is yours to book |
| Any use with a pump | A pump suited to the tank and the use | Wiring is for a licensed electrician |
Start with the simple end. You can add the house connection later if the sums work out.
Questions to settle before you buy a tank
- What is the water for? That decides how much equipment you need.
- How big is your roof? See what size rainwater tank you need.
- Where will the overflow go? A full tank with no clear overflow causes damage.
- Do local watering rules apply? Check your council and state or territory water authority.
- Are rebates or tank rules involved? They change by state, council and year, so ask before you buy.
- Who will do the licensed work? Find a plumber before you order the tank.
Frequently asked questions
What do you need for rainwater harvesting at home?
A roof catchment with gutters, leaf screening and a first flush device, a tank, an overflow path and, if you want pressure, a pump. Using the water inside the house adds a licensed plumbing connection and a backup supply.
Can I use harvested rainwater inside the house?
Yes, in many cases, but connecting a tank to household plumbing is licensed plumbing work and the rules differ by state and territory. Ask your plumbing regulator and your council before you start.
Is harvested rainwater safe to drink?
Do not assume so. Roof runoff can carry contaminants and tanks can grow bacteria. If you want to drink it, get it tested by an accredited (NATA) laboratory rather than relying on a home kit.
Is rainwater harvesting worth it just for the garden?
Often, because garden watering needs no treatment and no connection to the house plumbing. Check local watering rules and any council requirements for tanks first.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- NHMRC. Australian Drinking Water Guidelines
- Australian Building Codes Board. National Construction Code — Volume Three (Plumbing Code of Australia)