Gas Hot Water System Cost (2026): Australian Installed Prices

A new gas hot water system costs about $1,800 to $3,800 installed in Australia in 2026, including GST, when you replace like with like. A mid-size continuous flow unit swapped onto an existing bracket and gas line sits at the lower end; a 170 litre storage tank with a new tempering valve and a tricky install sits towards the top. Converting from one type to another, or from electric to gas, costs more because the pipes, gas supply and power may all need changing.

Hot water installation involves water, gas and sometimes electrical work. The water side must be done by a licensed plumber and the gas side by a licensed gasfitter; most hot water installers hold both licences. If the new unit needs a power point, that must be installed by a licensed electrician. The prices below are indicative, so get at least three written quotes and make sure each one is for the same size and type of unit.

Installed prices for common gas systems

LPG versions of most models cost about the same to buy. The difference is the fuel supply: you need LPG cylinders or a tank on site, and LPG generally costs more per unit of energy than mains natural gas. If you are not yet connected to gas at all, read our gas installation cost guide for connection and pipework prices before deciding.

Continuous flow or storage?

Continuous flow (sometimes called instantaneous) systems heat water only when a hot tap is turned on. There is no tank to keep hot, so no standby heat loss, and you cannot run out of hot water as long as the unit is big enough. They are compact and wall-mounted, which frees up space beside the house.

The catches are gas supply and flow. A large continuous flow unit draws a lot of gas at once, and an older house with a small gas pipe or a low-capacity meter may not deliver enough. If the pipe is undersized, the water runs lukewarm when two showers are on. Continuous flow units also need a 240 volt power point for the electronics and ignition, and there is a short wait for hot water to arrive at the tap.

Storage systems keep a tank of water hot, ready to go. They are simple, they do not need power (on most outdoor models), and they suit houses with a small gas supply. The downsides are standby heat loss from the tank, the space it takes up and the fact that a big household can run the tank dry. Storage tanks also have a shorter typical life than continuous flow units.

As a rough guide, continuous flow suits most families with mains gas and an adequate gas line. Storage suits smaller gas supplies, homes where power to the unit is awkward, and households that use hot water in short bursts.

Getting the size right

An undersized system is the most common complaint after a new hot water install. Here is a starting point; your plumber should confirm it against your household and the number of outlets that run at once.

• 16 L/min continuous flow: one bathroom, one or two people, one shower at a time.
• 20 L/min: one to two bathrooms, two to four people.
• 26 L/min: two bathrooms, a family of four or five, a shower and the kitchen tap at the same time.
• 32 L/min: three or more bathrooms, or homes with high-flow shower heads.
• 135 L storage: one to three people.
• 170 L storage: three to five people.

Cold winter mains water, such as in Hobart, Canberra and inland Victoria, means a continuous flow unit has to raise the temperature further, so it delivers less hot water per minute than in Brisbane or Perth. Plumbers in cold climates often size up one step.

What a gas hot water install costs around Australia

These are typical installed prices for a like-for-like 26 L/min continuous flow replacement in each city, including GST.

Three real-world installs

All amounts include GST.

Like-for-like continuous flow in Hornsby, NSW

A 15-year-old 26 L/min unit on the side wall of a four-bedroom brick home had a failed heat exchanger. The gas line and power point were already in place.

Storage to continuous flow in Morphett Vale, SA

A family of five kept running out of hot water from their 135 litre gas tank. They switched to a 26 L/min continuous flow unit, which needed a bigger gas pipe from the meter and a new outdoor power point.

The gas line upgrade was the line item the family had not expected. A good installer checks the gas pipe size and meter capacity before quoting a conversion. For the power point side, our electrician cost guide covers call-out and small-job prices.

Weekend emergency storage swap in Joondalup, WA

A 135 litre gas storage tank started leaking from the base on a Saturday morning. The owners chose a like-for-like tank so the job could be done the same day.

Had they turned off the gas and cold water at the tank and waited until Monday, the labour would likely have been $200 to $300 less.

Comparing gas with other hot water types

Gas is no longer the default it once was. Electricity prices, rooftop solar and government policy have all shifted the maths, so it is worth comparing before you replace like with like.

Heat pumps and solar water heaters can attract federal small-scale technology certificates, which reduce the upfront price, and some states offer extra rebates. Our solar hot water cost guide explains how that works. The federal government's Your Home guide to hot water systems is a good neutral comparison of running costs and emissions.

State rules that affect gas hot water

Policy on household gas is changing, and it varies by state. Victoria stopped new gas connections for new homes that need a planning permit from 1 January 2024 and has announced further rules to move existing homes towards electric hot water when gas units reach the end of their life. The ACT has also stopped most new residential gas network connections and plans to phase out gas. The details and start dates have changed more than once, so check the current position with Energy Safe Victoria or the Victorian Government, or with Access Canberra in the ACT, before you buy a new gas unit.

In other states, replacing a gas hot water system with another gas unit is allowed, but energy efficiency rules apply. New gas water heaters must meet minimum energy performance requirements, and many installs must comply with the gas installation standard AS/NZS 5601.1, which covers flue clearances from windows, doors and boundaries. An outdoor unit that was legal when installed 15 years ago may not meet current clearances, and the installer may need to move it.

Licences, compliance and safety

Installing a gas hot water system is both plumbing and gasfitting work. In every state and territory it must be done by a licensed plumber and a licensed gasfitter, or one person who holds both licences. That includes disconnecting the old unit. A handyman cannot legally do any part of it, and our article on whether a handyman can do plumbing explains why.

• NSW: plumbers and gasfitters are licensed by NSW Fair Trading, and gas work requires a certificate of compliance.
• Victoria: plumbers and gasfitters are registered or licensed with the Building and Plumbing Commission; Energy Safe Victoria oversees gas safety. A compliance certificate is required for most gas work.
• Queensland: the plumbing side needs a QBCC licence, and the gas side needs a gas work licence from Resources Safety and Health Queensland.
• WA: Building and Energy licenses plumbers and gasfitters and requires a notice of completion for gas work.
• SA, Tasmania, ACT and NT: plumbers and gasfitters are licensed by Consumer and Business Services, CBOS, Access Canberra and the relevant NT boards respectively.

Every new hot water installation needs a tempering valve or equivalent so that hot water at bathroom outlets is delivered at no more than 50 degrees Celsius, while the system itself keeps stored water hot enough to control bacteria. Your installer will set this up; do not ask them to bypass it.

If you smell gas near the unit, turn off the gas at the meter, avoid using switches or flames, get out of the house and call your gas distributor's emergency line. Do not try to repair a gas appliance yourself.

Running costs and lifespan

Gas running costs depend heavily on your tariff, the gas price in your state, the number of people in the house and how long everyone showers. Continuous flow units avoid the standby losses of a tank, so for most households they cost less to run than an equivalent storage unit. Look at the energy rating label when comparing models; a higher star rating means less gas for the same hot water.

Gas storage tanks commonly last 8 to 12 years. Hard water and lack of maintenance shorten that. Continuous flow units often last 12 to 20 years, with occasional parts such as igniters and flow sensors replaced along the way.

Simple maintenance helps. Gently operate the pressure and temperature relief valve lever on a storage tank about every six months, as most manufacturers recommend, and have the valve replaced at the interval in your manual, often about five years. Storage tanks have a sacrificial anode that protects the tank lining; replacing it every few years, usually for $200 to $400, can add years to the tank's life. Continuous flow units benefit from a service every few years. Check the manufacturer's manual for the exact intervals, as warranties may depend on them.

Signs your system is on the way out

• Water pooling around the base of a storage tank, or rust stains on the tank jacket.
• Rusty or discoloured hot water.
• Hot water running out faster than it used to.
• The pilot light going out often, or a continuous flow unit showing error codes.
• Popping or rumbling noises from a storage tank, which usually means sediment build-up.
• A system older than about ten years for storage, or fifteen for continuous flow, that needs a significant repair.

Replacing a failing unit on your own schedule is cheaper than an emergency swap, and it gives you time to compare gas with a heat pump or solar.

LPG hot water: what changes

Plenty of Australian homes, especially in regional areas, Hobart, parts of Brisbane and new estates without mains gas, run hot water on LPG. The units look the same as natural gas models but are built or converted for LPG, and the two are not interchangeable without a factory conversion kit fitted by a gasfitter. Buy the right version from the start.

An LPG setup needs cylinders, usually two 45 kg bottles on a changeover regulator so you can swap one while the other keeps running, or a larger tank filled on site. Your gas supplier may charge an annual rental per cylinder, and bottle delivery is priced per refill. Continuous flow units can empty a bottle faster than people expect in winter, so ask the installer to size the bottle setup to your usage.

Because LPG usually costs more per unit of energy than mains gas, the running cost gap between gas and a heat pump is often wider for LPG households. If you are on LPG and your system has failed, it is worth getting a heat pump quote alongside the gas one.

Ways to keep the cost down

Replace before it fails. A planned swap on a weekday is cheaper than a weekend emergency, and you can shop around for the unit. If your storage tank is past ten years old and showing rust, get quotes now.

Stick with the same type and location where it makes sense. Like-for-like swaps avoid new gas pipe runs, relocated water pipes and electrical work, which are where conversion budgets blow out.

Get the gas line checked before you commit to a conversion. A bigger continuous flow unit is pointless if the existing pipe cannot feed it, and finding out after the unit is on the wall costs a return visit.

Ask about the unit warranty and who honours it. Some low-priced units have short warranties or no local service agent, which can make a cheap unit expensive when a part fails in year three.

What a good quote includes

Ask each installer to list the exact make and model, the flow rate or tank size, labour, removal and disposal of the old unit, the tempering valve, any gas line or pipework changes, any electrical work and who does it, the compliance certificate and the warranty on both the unit and the labour.

Red flags include a quote with no licence numbers, a price far below the others that excludes the tempering valve or disposal, an installer who will not check the gas supply before quoting a conversion, and pressure to pay in cash. You can compare hot water specialists near you or licensed gasfitters in your area, and our plumber cost guide lists hourly rates if you are getting smaller jobs done at the same visit.

How long the job takes

A like-for-like swap takes two to four hours, and most installers can do it the same day or next day if the unit is in stock. Conversions that need a new gas line or a power point take most of a day and may need a second visit from an electrician. Plan to be without hot water for at least half a day.

Where Yakka fits

Installing a gas hot water system is licensed plumbing and gasfitting work, so Yakka Labour does not do it. A Yakka worker can help with the parts around the install, such as clearing an overgrown side passage so the installer can get the old tank out, carrying a heavy unit to an awkward location, and taking away packaging and rubbish afterwards.

Disconnection of the old unit, the gas and water connections and any electrical work must stay with licensed trades. Book a licensed plumber and gasfitter for the install and check their licence numbers with your state regulator.