What temperature should you heat a pool to?

Guideposts, not one perfect number

World Aquatics competition rules specify a pool temperature range of 25–28°C. That is a reference for competitive swimming, not a universal recommendation for every household or activity.

Preferences vary. A swimmer exercising continuously may find water comfortable that feels cool to somebody standing or playing. Try your own pool at a measured temperature before assuming it needs to be several degrees warmer.

Warmer is not automatically better. Follow equipment limits and relevant safety guidance. For young children, older swimmers or anyone with health considerations, personalised health advice takes priority over a general comfort guide.

Do not confuse approval settings with comfort advice

You may see temperatures quoted in building sustainability assessments such as BASIX in NSW. These settings are part of a particular project approval and energy-assessment framework, not a national list of ideal swimming temperatures.

Check current requirements for your own project with the relevant assessor or installer. Do not treat a figure from an approval guide as a blanket legal operating limit for every existing pool or spa.

Why one degree matters

Increasing the difference between the water temperature and its surroundings generally increases the heat the heater must replace. A higher target affects ongoing maintenance as well as the initial warm-up.

There is no single reliable dollar figure for an extra degree. Climate, season, cover use, pool size, tariff and operating efficiency all change the result.

Compare two otherwise identical scenarios in the sizing tool, one degree apart. The monthly figures are indicative estimates, not actual bills or guaranteed savings.

A practical way to choose

• Start with the temperature the people who actually swim find comfortable
• Decide which months you really want to maintain that temperature
• Compare the estimated heating demand and running cost at a slightly lower target
• Allow enough warm-up time rather than assuming a change will be instant
• Use a cover when the pool is not in use, and remove it before swimming

Pools and spas are different jobs

A spa usually has a smaller volume and a different pattern of use, so rapid heating may be more important than maintaining a large pool all season. That is one reason gas can suit some spa installations.

Do not use a pool comfort range as spa safety advice. Follow the spa manufacturer’s instructions, applicable requirements and health advice for the people using it.

Gather before you decide

• Who swims, and whether they are doing laps, playing or relaxing
• Your current measured water temperature and preferred target
• The months you want to maintain that target and your cover routine
• Your electricity usage rate so the estimate uses your own tariff

Worth professional input

Ask an installer about controls and schedules that make a realistic target easy to maintain. For health-related temperature questions, speak to a qualified health professional rather than relying on a heater-sizing guide.