A dead hot water system is one of the few household failures that gets fixed within 24 hours no matter what it costs, which is exactly why it pays to understand pricing before you are standing in a cold shower making panicked phone calls.
This guide covers what each system type costs to buy and install in Australia, how running costs compare over the life of the unit, and the questions that stop you overpaying on a distress purchase.
Quick price summary
Fully installed, like-for-like replacement prices in Australian metro areas typically land in these ranges. Regional installs, difficult access and relocations add to every figure.
- Electric storage (250 to 315L): $1,200 to $2,200 installed
- Gas storage (135 to 170L): $1,300 to $2,500 installed
- Gas instantaneous (continuous flow): $1,500 to $3,000 installed
- Heat pump: $2,500 to $5,500 installed, before rebates
- Solar (roof-mounted with electric boost): $4,000 to $8,000 installed
Electric storage: cheapest to buy, dearest to run
Electric storage tanks are the workhorse of Australian homes. The unit itself is cheap, replacement is fast because the plumbing rarely changes, and any licensed plumber can do a swap in a morning.
The catch is running cost. Heating water with a resistive element is the most expensive way to do it, and hot water is typically a quarter of a household electricity bill. If you have solar panels or plan to get them, a heat pump or a timer-controlled element that heats during the day changes the economics substantially.
Gas: storage versus instantaneous
Gas storage units heat a tank continuously and recover quickly after heavy use. Gas instantaneous (continuous flow) units heat water only as you use it, never run out, and hang on a wall taking almost no space.
Instantaneous units cost more up front and may need a larger gas line and a power point, which is where installation quotes vary the most. If your home already has continuous flow, replacement is straightforward. Converting from storage to instantaneous is a bigger job worth two or three quotes.
Worth knowing: several states are phasing back gas connections in new builds, and gas prices have risen steadily. If your gas cooktop is the only other gas appliance, some households now find it cheaper long-term to electrify fully and drop the gas supply charge entirely.
Heat pumps: highest efficiency, biggest rebates
A heat pump extracts heat from the air to warm the water, using around a quarter to a third of the electricity of a standard electric tank. That efficiency is why federal small-scale technology certificates (STCs) and several state schemes discount them heavily, sometimes by more than a thousand dollars.
Two practical caveats. First, heat pumps have a compressor, so they make noise comparable to a quiet air conditioner; placement near a bedroom window needs thought. Second, quality varies widely between brands. A cheap unit that fails at year six is no bargain against a quality tank that runs fifteen years, so ask the plumber what they would put in their own home.
What drives the installation price up
Two identical units can differ by a thousand dollars installed because of site factors. Knowing them helps you read a quote intelligently.
- Relocating the unit or switching fuel type (new pipe runs, gas lines or circuits)
- Difficult access: tight side passages, roof spaces, apartments and internal cupboards
- Compliance work: tempering valves, drain lines, seismic strapping and gas certification where the old install predates current rules
- Disposal of the old unit and any switchboard work for heat pumps or boosted systems
- After-hours emergency replacement versus a booked weekday job
Repair or replace?
A leaking tank is terminal: once the cylinder itself weeps, replacement is the only fix. Valves, thermostats and elements, on the other hand, are all repairable, usually for a few hundred dollars.
Age is the deciding factor. Most storage tanks last 8 to 12 years, longer with a sacrificial anode replacement around the halfway mark. Spending $400 repairing a 10-year-old tank is usually money down the drain; the same repair on a 4-year-old unit is an easy yes.
Frequently asked questions
How long does a hot water system replacement take?+
A like-for-like swap takes 2 to 4 hours once the plumber has the unit on the truck. Fuel-type changes or relocations can take a full day. Most metro plumbers can do same-day or next-day replacement for common sizes.
Can I claim a rebate on a heat pump hot water system?+
Yes. Federal STCs apply Australia-wide and are usually taken off the quoted price by the installer. Some states run additional schemes on top. Ask the plumber to show the price before and after incentives so you can compare fairly against a standard tank.
What size hot water system do I need?+
As a rule of thumb: 1 to 2 people suit 125 to 160L electric or a 16 to 20L/min continuous flow unit; 3 to 4 people suit 250 to 315L electric or 20 to 26L/min continuous flow; 5 or more suit 315 to 400L or 26 to 32L/min. Off-peak electric tariffs need a bigger tank because water is heated only overnight.
Is it illegal to install my own hot water system?+
Yes. Hot water systems involve sanitary plumbing, tempering valves and often gas or fixed electrical wiring, all of which legally require licensed trades in every Australian state and territory. DIY installation voids the warranty, risks scalding injuries and can void home insurance.