Signs it's time to replace
- Water seeping from the tank itself, not from a valve or a fitting.
- Rusty water from the hot taps while the cold runs clear.
- A repair that keeps coming back, or a new fault soon after the last one.
- More people in the house than the tank was chosen for.
- An ageing gas unit in a Victorian home, and you'd rather pick its electric successor before it stops.
Planning the replacement
Photograph the label
Brand, model, fuel, tank size and install date are all on it. The plumber uses them to see what's connected and what can be reused.
Work out what the house needs
Count the people and the showers that run at once. Our sizing guide and size checklist help you avoid buying too small or too big.
Choose the type
Gas, electric storage, heat pump and solar each suit different houses. The comparison sets them side by side, and the gas or heat pump guide narrows it down.
Check discounts before you commit
Some programs need the paperwork sorted before the install. Read the hot water rebate guide first.
Book the swap
A plumber will drain and remove the old unit, connect the new one, fit the valves it needs, test it and hand you whatever paperwork your state requires.
What changes the job
| Why it matters | |
|---|---|
| Same fuel, same spot | Usually the simplest swap: the pipes and the gas or power are already there. |
| A change of fuel | Gas to electric means capping the gas and arranging a suitable power supply. Electric to gas needs a gas line run to the unit. |
| A heat pump | It needs outdoor air around it, and a spot where its fan won't keep anyone awake. |
| Solar | Collectors go on a roof that gets the sun, so the roof and the way up to it matter. |
| Access | Tight cupboards, stairs, roof spaces and long carries all add work. |
| Temperature control | Depending on your state, a tempering valve may have to go in with the new unit. |
Victoria: the 2027 gas rule
In an existing Victorian home, a gas hot water system that reaches the end of its life on or after 1 March 2027 must be replaced with an efficient electric one, such as a heat pump. That's how Solar Victoria and the Government's 2025 announcement describe it.
It isn't a ban on working systems. A gas unit that still does its job can stay, and it can be repaired if it breaks down. Rentals have their own standards, which allow an electric-boosted solar system as well as a heat pump.
We haven't found the regulation itself, only the announcement and Solar Victoria's page, so check current rules before you order anything. The detail is on our page about Victoria's gas hot water rule.
Before the plumber arrives
You can
- Clear a path to the old unit, and note any stairs or tight corners.
- Measure the space if the new unit has to fit a cupboard or alcove.
- Find any old paperwork: the purchase date can matter for rebates.
- Decide where the water can go when the old tank is drained.
Leave to a licensed plumber
- Disconnecting gas, water and the flue.
- Fitting the relief valve, the isolating valve and any temperature control your state requires.
- Removing and disposing of the old tank.
- Lodging or handing over the compliance paperwork.
Rules and paperwork for a replacement
Hot water is licensed plumbing work. Ask for the plumber's licence number and look it up: our licence guide shows where, state by state.
Victoria. Plumbers are registered or licensed for each class of work, and only a licensed plumber can issue a compliance certificate.
NSW. Replacing an existing hot water system is minor work, so no Notice of Work has to be lodged before it starts.
South Australia. A water heater replacement needs an electronic certificate of compliance, and you should have it within 7 days of the job finishing.
Western Australia. Replacing a water heater isn't minor work. The contractor must give you a certificate of compliance within five working days.
Several states also require a tempering valve when the heater is replaced, and the rules differ: see tempering valves. For the rest, read our compliance certificate guide.
Questions to ask before you say yes
- Is the old system really finished, or would a repair carry it to a planned swap?
- Which types suit this house, and which would you rule out?
- Is the new model eligible for any discount or rebate here, and who does that paperwork?
- Does a tempering valve need to go in, and where?
- What happens to the old unit?
- What certificate or record do I get when you're done?
What we would do
Don't wait for the cold shower. If your system is old, or you're in Victoria with an ageing gas unit, choose the replacement now: compare types, check discounts and pick a day that suits you. When you book, use a plumber who replaces hot water systems every week. They'll know the valves and the paperwork your state expects, and they won't be guessing at sizes.