Can I replace a hot water system myself?
Short answer
No. Replacing a hot water system is licensed plumbing work in every Australian state and territory, and gas hot water systems also need a licensed gasfitter. It involves the water supply, a pressure and temperature relief valve, often a tempering valve, and for gas or electric units, gas or electrical connections. What you can do is get it quoted quickly: note the model plate, the tank size and how the unit is powered, and send clear photos.
When the hot water goes, it’s urgent, and it’s tempting to buy a unit and fit it yourself. In Australia that’s not an option: every state treats it as licensed work.
The rules
| Job | Who can do it |
|---|---|
| Replace an electric hot water system | Licensed plumber (and electrician for any wiring changes) |
| Replace a gas hot water system | Licensed plumber and gasfitter |
| Replace a solar or heat pump system | Licensed plumber (plus electrician for wiring) |
Queensland’s list of plumbing owners can do themselves specifically excludes hot water systems, and NSW requires a licence for any plumbing work regardless of cost.
Why it’s licensed
A hot water system stores water under pressure at high temperature. It needs a working pressure and temperature relief valve, correct connections to the water supply, and in most homes a tempering valve so the water at your bathroom taps can’t scald. Gas units add gas connections and flueing. A mistake can mean scalding, a burst tank or a gas leak.
Getting it replaced fast, and priced right
- Photograph the model plate (the sticker on the side of the unit). It shows the brand, model, capacity and whether it’s gas or electric.
- Photograph the whole unit and the pipes and connections around it, plus where it sits (outside, garage, cupboard).
- Note the symptoms: no hot water at all, lukewarm water, leaking from the tank or valve, or water that runs out quickly.
- Send the same brief to two or three plumbers. With photos, many can quote a like-for-like replacement without a site visit.
- Ask what’s included: removal of the old unit, a new tempering valve if needed, and compliance paperwork.
For a template, see how to write a job brief tradies can quote from.
Signs it’s time
- The tank is leaking, rusty at the base, or water is pooling underneath
- The water is discoloured or smells, or the unit is noisy
- It’s more than about 10 years old and giving trouble
If water is leaking from the tank itself, turn off the cold water supply to the unit and, for electric units, the hot water circuit at the switchboard, then call a plumber.
Sources
Every rule on this page is taken from these official sources. If a rule has changed, please tell us and we’ll fix it.
This guide is general information, not legal or professional advice. Rules differ between states, councils and individual properties, and they change. Confirm with your state regulator or council before starting work, and if in doubt, get a licensed tradesperson.