The Complete Australian Instant Hot Water Buyer's Guide
Buying an instant hot water system in Australia? Here is everything we ask on the phone first, in the order we ask it.
The best instant hot water system in Australia for most homes is a gas continuous flow unit: the Midea M26 from $849 in Melbourne, Adelaide and colder areas, or the Midea M20 from $749 in warmer cities. With no gas on site but 3 phase power, the best instantaneous hot water system is the Stiebel Eltron DEL 27 Plus at $1,399.
Single phase and no gas is the hard case, and it gets an honest answer below. The whole decision comes down to three things: what power and gas the house has, how cold your incoming water gets, and how many showers run at once.
Want your exact size? Our instant hot water sizing calculator works out the kW or litres a minute you need in winter, checks single or 3-phase power, then shows the units that fit.
The best instant hot water systems by situation
The right instant hot water system depends on the supply at your house, so the table starts there and not with the brand.
| Your house | Buy this | Output | Price |
|---|---|---|---|
| Gas, 2 to 3 bathrooms, or a cold city | Midea M26 | 26 L/min | From $849 |
| Gas, smaller home, warm city | Midea M20 | 20 L/min | From $749 |
| Natural gas, unit must go indoors | Midea M26 Internal | 26 L/min | From $1,569 |
| 3 phase, no gas, best all rounder | Stiebel Eltron DEL 27 Plus | 28 kW | $1,399 |
| 3 phase, warm city, one bathroom | Stiebel Eltron DEL 18 Plus | 19.4 kW | $1,365 |
| 3 phase, lowest price | Stiebel Eltron DHB-E 18 LCD | 19.4 kW | $1,139 |
| 3 phase, exact temperature to 60°C | Stiebel Eltron DHE 27 | 28 kW | $1,545 |
| Single phase, one sink or basin | Stiebel Eltron DHC-E 8/60 | 9.5 kW | $915 |
Prices current as of November 2026, AUD including GST, unit only. Gas prices vary slightly between Natural Gas and LPG. Installation not included.
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Step 1: Check what your house can run
Your gas and electrical supply decides which instant hot water systems are even possible, so check it before you compare anything else.
Mains gas or LPG on site means a gas continuous flow unit is the easy answer. No gas means electric, and electric means looking at the switchboard. A proper whole house electric instant unit needs 3 phase power, full stop. Three main switches ganged together usually means 3 phase, and one main switch usually means single phase. If you are not certain, ask a licensed electrician before you buy.
Current draw matters too. The DEL 18 Plus pulls 27A per phase and the DEL 27 Plus pulls 38.9A, so the electrician needs to confirm the board and the supply can carry it. Our guide to single phase vs 3 phase instant hot water goes through it properly.
Step 2: Size it for winter, not for the brochure
An instant hot water system has to be sized for your coldest incoming water, because the unit has to lift that water to shower temperature on the fly.
This is where people get caught. A unit that feels great in February can run out of grunt in July, because the same kW has to do a much bigger temperature lift. One standard shower at 40°C in winter needs roughly these figures:
| City | Power for one winter shower | Sensible electric pick |
|---|---|---|
| Brisbane | About 15 kW | DEL 18 Plus (19.4 kW) |
| Sydney | About 17 kW | DEL 18 Plus (19.4 kW) |
| Melbourne | About 19 kW | DEL 27 Plus (28 kW) |
| Canberra | About 21 kW | DEL 27 Plus (28 kW) |
A 28 kW unit gives roughly 13 to 17 L/min. Two showers at the same time is a gas job: 20 L/min in warm cities, 26 L/min in Melbourne, Adelaide and anywhere colder. Here is the part that makes the choice easy: the DEL 27 Plus costs only $34 more than the DEL 18 Plus. If the supply can carry it, buy the bigger one. Our instantaneous hot water sizing guide walks through it by city.
Step 3: Gas or electric instant hot water
Gas continuous flow is cheaper to buy and cheaper to run than electric instant hot water when the house already pays for a gas connection.
| Three person Sydney home | Per 8 minute winter shower | Rough yearly cost |
|---|---|---|
| Midea M20, mains gas you already have | About 37c | About $360 |
| Midea M20, hot water the only gas appliance | About 37c plus supply charge | About $650 |
| Midea M20, bottled LPG | About 64c | About $670 |
| Stiebel Eltron electric instant | About 75c | About $725 |
Worked estimates at 4 cents per MJ mains gas, 7 cents per MJ LPG and 33 cents per kWh electricity, as of November 2026. Your tariffs will differ.
Electric earns its place in other ways. There is no flue, no gas line and no outdoor wall needed, and a DEL unit fits in a cupboard. For an apartment or a house going all electric, 3 phase instant is the tidy answer. The full breakdown is in our cheapest hot water system to run guide, and the head to head is in electric vs gas instantaneous hot water.
Step 4: Pick the model
Once fuel and size are settled, the model comes down to where the unit mounts and how much temperature control you want.
Midea M Series gas continuous flow
The Midea M26 is the default gas pick because 26 L/min covers 2 to 3 bathrooms for $100 more than the M20. It has a 6.5 star energy rating, 86.6% thermal efficiency and inbuilt frost protection, and it comes pre-set to 50°C. Both outdoor units come in Natural Gas or LPG, so pick the right one at checkout. The M26 Internal is Natural Gas only and needs a power flue. See Midea M20 vs M26 for the side by side.
Stiebel Eltron 3 phase electric
The Stiebel Eltron DEL Plus range is the default electric pick because it caps output at 50°C, so no tempering valve is needed, and it carries a 7 year manufacturer warranty. It is made in Germany. The DHE range goes to 60°C with finer control for $150 or so more, and the DHB-E 18 LCD is the budget way into 3 phase at $1,139. Our Stiebel Eltron DHE vs DEL comparison covers which suits whom.
Single phase electric
Single phase electric instant hot water tops out at 9.5 kW, which is about 5 L/min in a Sydney winter, so it is a sink or basin unit and not a winter shower. The DHC-E 8/60 draws 40A on 240V and suits a kitchen, a laundry or a remote basin. Anyone selling you a single phase unit for a family bathroom is selling you cold showers. No gas and no 3 phase? Keep a tank, or price a 3 phase upgrade with your electrician. For boiling water at the sink, the Stiebel Eltron HOT 2.6 N starts at $999.
Buying instant hot water online: what to check
Buying an instant hot water system online is straightforward as long as you confirm the gas type, the supply and the installer before you pay.
- Gas type. Natural Gas and LPG units are not interchangeable off the shelf. Check what is at the house.
- Unit only. Online prices cover the unit. Your plumber, gas fitter or electrician quotes the install.
- Your installer's view. Send them the model before you order, especially when changing from a tank.
- Pipe size. Gas units need a gas line big enough to feed them at full fire, and an old tank's line may not be.
- Temperature rules. Hot water to bathrooms has limits in Australia. Our 50 degree guide explains them.
Swapping out a storage tank is a bigger job than swapping like for like. Read replacing a hot water tank with instant first, because a gas line upgrade or a new 3 phase circuit is usually the biggest extra cost.
What about Rinnai, Rheem and heat pumps
Rinnai and Rheem make good continuous flow units and are the names most plumbers mention first.
We do not stock them. Compare them with the Midea on the same three numbers: litres a minute, star rating and price. A heat pump storage system is cheaper again to run, but it costs several times more to buy, needs outdoor room for a tank and is a different kind of product. We do not currently sell one. Our heat pump vs instant vs gas guide lays out that trade off honestly.
Frequently asked questions
What is the best instant hot water system in Australia?
The best instant hot water system in Australia for most homes is a gas continuous flow unit such as the Midea M26 from $849, which delivers 26 L/min for 2 to 3 bathrooms. For homes with 3 phase power and no gas, the best pick is the 28 kW Stiebel Eltron DEL 27 Plus at $1,399.
How much does an instant hot water system cost in Australia?
An instant hot water system in Australia costs from $749 for a gas continuous flow unit and from $1,139 for a 3 phase electric unit, as of November 2026. Installation is extra and is quoted by your licensed plumber, gas fitter or electrician based on the site.
Can you run an instant hot water system on single phase power in Australia?
Yes, but single phase electric instant hot water systems top out at 9.5 kW, which suits a sink or basin and not a winter shower. A whole house electric instant system needs 3 phase power, and a home with neither gas nor 3 phase is usually better off keeping a tank.
Is gas or electric instant hot water cheaper to run in Australia?
Gas is cheaper to run in Australia when the home already has mains gas, at about $360 a year against about $725 for electric for three people in Sydney, as of November 2026. If hot water is the only gas appliance, the supply charge lifts gas to about $650 a year and most of the gap disappears.
What size instant hot water system do I need for two showers?
Two showers running at once need a gas continuous flow unit: 20 L/min in warmer cities and 26 L/min in Melbourne, Adelaide and colder areas. Even a 28 kW electric unit only gives roughly 13 to 17 L/min, which is not comfortably two showers in winter.
Still not sure? Ask us before you buy
Tell us your city, your power supply, whether you have gas and how many bathrooms you run, and we will tell you which unit fits, including if the answer is that you should keep your tank.
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Going electric? See the full Stiebel Eltron instant water heater range.
This guide is general information for Australian homeowners and is not a substitute for advice on your specific site. Electrical work must be done by a licensed electrician, and gas and plumbing work by a licensed gas fitter or plumber. 3 phase units need a 3 phase supply. Confirm final sizing with us before you buy.