Hot Water Systems in Perth: When to Repair, When to Replace and Which Type to Choose

A failed hot water system is one of those problems that always seems to happen at the worst possible time. Monday morning. Middle of winter. Guests arriving Friday. It's the kind of thing most people don't think about until it stops working, at which point the decision about what to replace it with has to be made quickly and under pressure.

This guide is for homeowners who'd rather think about it before that happens. It covers how long systems last, what the warning signs of failure look like, the types of systems available in Perth, and what the licensing and compliance requirements are for installation in Western Australia.

How long does a hot water system last?

Service life varies by type and how well the system has been maintained, but as a general guide:

• Electric storage systems: 8 to 12 years

• Gas storage systems: 8 to 12 years

• Gas continuous flow systems: 15 to 20 years

• Solar hot water systems: 15 to 20 years with good maintenance

• Heat pump systems: 10 to 15 years

If your system is approaching or past these ages and starting to show signs of trouble, the cost-benefit of repairing it versus replacing it shifts significantly. Repairing an old system buys time, not certainty.

Warning signs your system needs attention

Running out of hot water faster than usual. In a storage system, this can indicate sediment buildup at the bottom of the tank reducing its effective capacity. In a continuous flow system, it can indicate a failing component.

Water that isn't getting as hot as it should. Could be a failing element in an electric system, a burner issue in a gas system or a thermostat that needs attention.

Rust or discolouration in the hot water. Discoloured water usually means the sacrificial anode inside the tank has failed and the tank itself is corroding. Once this starts, replacement is typically the right call rather than repair.

Visible corrosion or moisture around the unit. Surface rust on the outside of the tank, moisture pooling at the base or corrosion around the fittings are all signs the system is deteriorating.

The pressure relief valve dripping constantly. The pressure relief valve is a safety device that releases water if pressure inside the tank gets too high. Occasional discharge is normal. Constant dripping is not and usually indicates a problem with either the valve or the system pressure.

The system is making unfamiliar noises. Rumbling, popping or banging from a storage tank is usually caused by sediment and scale buildup. It doesn't necessarily mean the system is about to fail, but it does mean it's working harder than it should be.

Types of hot water systems available in Perth

Perth's climate, relatively affordable gas network and strong solar resource mean homeowners have genuine options across all system types. Here's a plain-English summary of each.

Electric storage systems

The most common type in older Perth homes and the simplest to replace like for like. Relatively low upfront cost, straightforward installation and widely available. Running costs are higher than gas or heat pump alternatives, particularly if the system is running on peak-rate electricity. Off-peak tariffs can reduce this significantly.

Gas storage systems

Faster recovery than electric storage and generally cheaper to run if your home is already connected to natural gas. Perth has good natural gas infrastructure across most metro suburbs. Atco Gas Australia manages the natural gas distribution network in WA and can advise on connection availability in your area.

Gas continuous flow systems

Heat water on demand rather than storing it, which means no standby heat loss and no running out of hot water provided the flow rate suits the household. Higher upfront cost than storage systems. Require adequate gas pressure at the meter and adequate gas pipe sizing. Well suited to larger households with high simultaneous demand.

Solar hot water systems

Perth is one of the best cities in Australia for solar hot water, with one of the highest average solar radiation levels of any capital city. Solar hot water systems use roof-mounted collectors to heat water directly, with an electric or gas booster for periods of low solar input. Higher upfront cost with meaningful long-term savings on running costs.

Heat pump hot water systems

Work similarly to a reverse-cycle air conditioner, extracting heat from the ambient air to heat water rather than generating heat directly. Significantly more energy-efficient than electric storage, particularly in Perth's climate where ambient temperatures are relatively high year-round. Eligible for government rebates in WA. Growing in popularity rapidly as running costs of electric storage become more apparent to homeowners.

The Clean Energy Council has useful resources on solar and heat pump hot water systems, including how to assess what's right for your home.

Government rebates and incentives in WA

WA homeowners replacing an existing hot water system with a heat pump or solar system may be eligible for financial incentives under the federal government's Small-scale Renewable Energy Scheme (SRES), administered by the Clean Energy Regulator. This scheme provides Small-scale Technology Certificates (STCs) that reduce the effective purchase price of eligible systems.

Synergy, the main electricity retailer for Perth metro households, also offers information on energy efficiency and rebate programs relevant to hot water systems. It's worth checking what's current at the time of purchase, as programs and eligibility criteria change.

A licensed plumber or hot water system supplier can advise on what rebates apply to your specific situation at the time of installation.

Licensing requirements for hot water system installation in WA

All hot water system installation and replacement in Western Australia must be carried out by a licensed plumber registered with Building and Energy under the Plumbers Licensing Act 1995 (WA).

If the system is gas-connected, the gas connection work must be carried out by a licensed gas fitter under the Gas Standards Act 1972 (WA).

If the system is electrically connected, the electrical connection must be carried out by a licensed electrician registered with EnergySafety WA.

Most hot water system replacements also require the plumber to lodge a Plumbing Notice with Building and Energy. This is a legal requirement, not a formality, and confirms the work has been done to the required standard.

Replacing a hot water system yourself is not legal in WA and voids most home insurance policies. It also creates significant issues if the property is sold and a pre-purchase inspection identifies unlicensed work.

Repair or replace?

The honest answer is that it depends on the age of the system, the nature of the fault and the cost of repair relative to replacement.

As a general guide, if a system is under eight years old and the fault is a single component like an element, thermostat or valve, repair usually makes sense. If the system is over ten years old, the fault is significant or the tank itself is showing signs of corrosion, replacement is generally the more sensible option. Paying to repair a system that fails completely six months later is not a good outcome.

A licensed plumber can assess the system and give you an honest view on whether repair or replacement is the right call.

This & That handles hot water system repair and replacement across Perth, working with licensed plumbers and gas fitters. Request a quote here or call 0487 606 491 to talk through what your system needs.