What Size Hot Water System Do I Need in Perth (2026)
In Perth the right hot water size is set by the number of people and their peak demand, with the sunny climate suiting solar and heat pump.
Your what size hot water system do i need details
Storage systems are sized by litres; continuous-flow systems by flow rate.
Continuous-flow systems never run out, so they can be sized a little smaller.
Below the typical range for this service.
Below the typical range for this service.
Where the money goes
Estimated breakdown for your configuration
An undersized tank runs out of hot water; an oversized one wastes energy keeping water you do not use hot. Size it to your household and when you use hot water most.
Ways to save
- Heat pump and solar systems cost more upfront but far less to run, and attract rebates.
- Continuous-flow systems suit smaller spaces and never run out, so can be sized tighter.
How we estimate this
A household of 3–4 typically needs a 250–315L storage system (or a continuous-flow unit) in 2026, costing roughly $1,100 to $5,000 supplied and installed depending on type. Larger households need more capacity.
Pricing reviewed: October 2026.
What a what size hot water system do i need costs in Perth
Sizing a hot water system in Perth begins with how many people use the home and how much hot water they draw at once, since the system must meet the peak, like a morning with several showers running together. A storage system is sized as a tank volume in litres big enough for that peak, so a larger household needs a larger tank, while a continuous-flow gas system is sized by its flow rate in litres per minute that keeps up with the outlets running at once.
Perth's hot, dry Mediterranean climate suits solar hot water and a heat pump especially well, because the abundant sun heats a solar system efficiently for most of the year and the warm air helps a heat pump, which can trim the running cost for the same household size. The incoming mains water is warm much of the year, easing the heating load. A storage tank holds the day's supply and can run short if drained, while a continuous-flow unit never runs out but is capped by its flow rate. A single-storey double-brick home commonly mounts the tank outside, and the isolation of the WA market rarely affects standard units. An off-peak electric storage household sizes the tank bigger to heat overnight.
A hot water system install is licensed plumbing work, and a gas unit also needs a licensed gas fitter, in Western Australia under WA Building Services, so a licensed plumber confirms the final size and installs it. For a Perth home, the clearest way to size hot water is by the number of people and the peak simultaneous demand, with the sunny climate suiting solar or a heat pump.
Compare against the national picture: What Size Hot Water System Do I Need in Australia →
What Size Hot Water System Do I Need in other cities
Frequently asked questions
How is hot water size worked out in Perth?
By the number of people and their peak demand, not the floor area, because the system must meet a peak like several showers at once, so a larger Perth household needs a larger tank or a higher continuous-flow rate.
Is solar hot water good in Perth?
Very good. The hot, dry Mediterranean climate and abundant sun heat a solar system efficiently for most of the year, and the warm air helps a heat pump, which can trim the running cost for a Perth household.
Tank or continuous-flow for a Perth home?
A storage tank holds the day's supply and can run short if drained, while a continuous-flow unit never runs out but is capped by its flow rate, so a large Perth household running several showers at once needs a high-flow unit or a big tank.
Do I need a licensed plumber in Perth?
Yes. A hot water system install is licensed plumbing work, and a gas unit also needs a licensed gas fitter, in Western Australia under WA Building Services, so a licensed plumber confirms the final size and installs it.