How to turn off your hot water system, and what not to touch
When a tank leaks or a pipe bursts, you want the water and the heat stopped fast. Here is what is yours to do, in the right order.
To turn off a hot water system, stop the heat source first, then stop the water coming in. On an electric system that means the switchboard. Then close the isolation valve on the cold inlet, and call a licensed plumber.
The order matters. A tank that keeps heating with no water coming in can build pressure and temperature, and that is the situation you are trying to avoid.
What do you do first on an electric system?
Switch the power off at the switchboard. Many homes have a labelled breaker for hot water, and some systems also have an isolating switch near the tank. Use the switchboard, and leave the tank cover alone.
If water is pooling near the system or the switchboard looks wet, do not go near it. Call a licensed electrician and keep everyone clear. Our page on a leaking hot water system covers what a leak can mean.
What about gas, solar and heat pump systems?
| System | Stop the heat | What you leave alone |
|---|---|---|
| Electric storage | Breaker at the switchboard | The element and thermostat behind the cover |
| Gas storage or continuous flow | Call a licensed gasfitter if you need the gas off | Gas connections, burner, pilot and flue |
| Heat pump | Switchboard breaker or the isolator the installer fitted | The refrigerant circuit and the unit casing |
| Solar with booster | Switch the booster off at the switchboard | Roof panels and pipework |
For gas, the rule is plain. Diagnosis is fine, intervention is not. If you smell gas, leave the building and call your gas emergency number from outside. Do not switch anything on or off inside.
How do you stop the water?
Close the isolation valve on the cold water pipe feeding the system. If you cannot find it or it will not turn, use the main shut-off for the property. Do not force a stiff handle with a wrench, since a snapped stem makes the leak worse. Our guide to the isolation valve shows where to look.
Do not open the relief valve to release pressure. It is a safety device and only a licensed plumber should touch it.
Is turning it off for a holiday different?
Yes, and usually it is not worth it. For a short trip, most households save very little by switching off, and the system reheats afterwards. For a long absence, switching off the power at the switchboard is reasonable. Check your manual for what the maker says, and have a plumber advise on gas models.
What to do next
- Call a licensed plumber. Tell them the system type and what you saw.
- Keep the power off until it has been checked. Do not switch it back on to test.
- Note where the water came from. A photo helps with the call and any warranty claim.
- Check the warranty. Terms on hot water system warranties often depend on a licensed installer.
The shut-down order, step by step
Follow the order below for an electric system. The reasons matter, because a tank that keeps heating with no water coming in can build pressure and temperature.
- Keep everyone clear if the area is wet. Water near the system or a wet switchboard means you call a licensed electrician and stay away.
- Switch the power off at the switchboard. Use the hot water breaker. This stops the heat without opening anything on the tank.
- Close the isolation valve on the cold inlet. This stops water coming in. Our guide to the hot water isolation valve shows where to look.
- Use the main shut-off if the valve will not turn. Do not force a stiff handle with a wrench, since a snapped stem makes the leak worse.
- Leave the relief valve alone. It is a safety device and only a licensed plumber should touch it.
- Call a licensed plumber. Tell them the system type and what you saw, and keep the power off until it has been checked.
If you smell gas at any point, leave the building and call your gas emergency number from outside.
Mistakes to avoid when you shut down a hot water system
In an emergency it is easy to reach for the wrong thing. These are the usual slips and what to do instead.
| Mistake | Why it is a problem | Do instead |
|---|---|---|
| Removing the tank cover | Wiring and the element sit behind it | Use the switchboard only |
| Shutting the water but leaving the power on | The tank can keep heating with no water coming in | Power first, then the cold inlet valve |
| Forcing a stiff valve | A snapped stem makes the leak worse | Use the main shut-off for the property |
| Opening the relief valve to release pressure | It is a safety device | Leave it for a licensed plumber |
| Switching it back on to test | It can restart a damaged system | Keep the power off until it is checked |
| Turning off gas inside the building after a smell | Switching anything on or off can be dangerous | Leave and call the gas emergency number from outside |
Photograph where the water came from before you call. It helps the plumber and any warranty claim.
Frequently asked questions
How do I turn off an electric hot water system?
Switch off the hot water breaker at the switchboard, then close the isolation valve on the cold inlet. Leave the tank cover alone, and call a licensed plumber.
Should I turn off the water or the power first?
Power first on an electric system, then the water. A tank that keeps heating with no water coming in can build up pressure and temperature.
Can I turn off the gas to my hot water system myself?
Leave gas work to a licensed gasfitter. If you smell gas, leave the building and call the gas emergency number from outside.
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.
- Australian Government, energy.gov.au. Hot water systems — types, installation and energy performance
- Australian Building Codes Board. National Construction Code — Volume Three (Plumbing Code of Australia)