There is no single correct pool temperature, which is inconvenient because it is the question everyone asks first.
What there is instead is a comfortable range that shifts depending on who is swimming and what they are doing in there, and a running cost consequence that grows disproportionately the higher you push it.
Understanding both is how you land on your own ideal pool temperature rather than someone else's.
Why there is no single answer
Water conducts heat away from a body far faster than air does. That is why still water at a temperature you would find pleasant as air feels cold, and why a small change in water temperature produces a large change in perceived comfort.
But how much heat your body is generating changes the equation entirely.
A lap swimmer working hard generates a lot of heat and needs the water to carry it away. Water that a child finds pleasant will feel oppressive to them after ten laps.
A child playing moves in bursts and spends time standing still. They cool quickly and have a higher surface area relative to body mass, so they feel cold sooner than adults in the same water.
Someone doing gentle exercise or therapy generates very little heat and is often in the water for extended periods, so they need it warmer again.
An adult lounging sits between the two.
So the same pool serving a family with young children, a parent doing laps at 6am, and a grandparent doing gentle movement is genuinely being asked to be three different temperatures.
The general comfort bands
These are commonly used guides rather than rules, and personal preference varies considerably.
Competitive and lap swimming sits at the cooler end. Serious swimmers frequently find water that feels pleasant to a casual bather uncomfortably warm once they are working.
General family swimming and recreation sits in the middle, and this is where most domestic pools are set. Comfortable to get into without a gasp, comfortable to stay in.
Young children, gentle exercise and therapeutic use sits at the warmer end. Less heat generated, longer time in the water, more warmth required.
Spas are a different category entirely, considerably warmer than any of the above, because you are sitting still. See spa heating.
The practical approach: pick a setpoint, live with it for a fortnight, and adjust by a single degree at a time. Everyone in the household will have an opinion, and the compromise is usually a degree below what the coldest family member wants.
Why each degree costs more than the last
This is the part that changes how people set their pool, and it is worth understanding properly.
Heat loss from a pool is driven by the difference between the water temperature and the surrounding environment. The bigger that gap, the faster the pool loses heat.
So when you raise your setpoint by a degree, two things happen at once. You have to add energy to get there, which is a one off. And then you have to keep replacing losses that are now permanently higher, every hour, for as long as you hold that setting.
The consequence: the cost of a degree is not linear. Going from a moderate setting to one degree warmer costs more than the previous degree did, and the one after costs more again. Pushing well above comfortable is where pool running costs get genuinely alarming.
The corollary is the useful bit. Dropping your setpoint by a single degree, if nobody in the household actually notices, is one of the most effective running cost reductions available to you. It costs nothing to try.
The cover changes this more than the thermostat
Before adjusting your setpoint, deal with evaporation.
Evaporation is the largest single heat loss mechanism in an outdoor pool, by a wide margin, and it peaks overnight when the air cools and the water does not. An uncovered pool spends every night giving your heating back to the sky.
A cover reduces that loss dramatically. In practical terms, a covered pool holds a higher temperature for the same energy input, which means you can either run warmer for the same cost or the same temperature for less.
If you are unhappy with either your temperature or your bill, the cover is the first thing to address, ahead of the thermostat and well ahead of the heater.
Seasonal strategy, rather than one setting
Most people set a temperature once and leave it. There is a better approach.
Peak summer. You may need no heating at all in warmer parts of Australia, and in the tropics the question can invert entirely into whether you need cooling. Reversible heat pumps can pull heat out of a pool that has become uncomfortably warm.
Shoulder seasons. This is where heating earns its keep, and where a sensible setpoint turns a three month pool into a nine month one.
Winter. If you are swimming through it, expect to hold a setting continuously and expect the cost to be highest here, because the gap between water and air is widest.
Extended absences. Drop the setpoint rather than switching off entirely. Reheating a fully cold pool on a heat pump takes a long time, so maintaining a lower baseline is usually both cheaper and more convenient than starting from cold. App and timer control makes this easy on modern units.
Regional differences across Australia
Your postcode changes what a given setpoint costs you, even for identical pools.
Tropical north. Long natural season, warm nights, minimal gap between water and air. Holding a temperature here is comparatively cheap, and cooling may be the more relevant capability.
South east Queensland and northern New South Wales. Comfortable through summer, cool either side. Shoulder season heating is where the value sits.
Sydney and coastal New South Wales. Bigger day to night swing, so overnight losses matter more and the cover becomes disproportionately valuable.
Melbourne, Adelaide and the temperate south. Cool nights well into the warmer months and genuine winter. Holding any setpoint costs more here because the gap is larger for more of the year.
Perth. Warm days, but the afternoon sea breeze strips heat off an open surface efficiently. Shelter and cover matter more than the raw temperature figures suggest.
Tasmania, ACT and the highlands. The most demanding conditions in the country. Year round swimming is achievable but has to be designed for from the outset.
There is a fuller breakdown in the complete pool heater guide.
Measuring it accurately
Worth a mention, because a surprising number of temperature complaints are measurement problems.
Your heater's display reads at the plant, not in the pool. Depending on pipe runs and whether the pump is running, those can differ.
Surface water is warmer than water at depth, especially on a sunny day in an unmixed pool. A thermometer floating on top will read high.
Cheap thermometers drift. If you are making decisions based on single degrees, it is worth having something you trust.
Check at the same time of day. Early morning, before solar gain, is the most honest reading and the one that tells you whether your heater is holding overnight.
Frequently asked questions
What temperature should I set my pool to?
Somewhere in the general recreational comfort band, adjusted for who actually swims. Start in the middle, live with it for a fortnight, and adjust one degree at a time.
Is a warmer pool less healthy?
Warmer water is chemically more active, so sanitiser is consumed faster and water balance needs closer attention. That is a maintenance consideration rather than a health one, but it does mean heating and water care go together.
Why does my pool feel colder than the display says?
Possibly a measurement issue, possibly stratification, possibly wind chill as you get out. Check with a trusted thermometer at depth, early in the morning.
How much does one degree cost?
It depends on your pool volume, climate, cover use, exposure and tariff, and it costs more for each additional degree. Anyone quoting a firm figure without those inputs is guessing. What is reliable is the direction: each degree costs more than the last.
Should I turn it off when we go away?
Drop the setpoint rather than switching off. Reheating from fully cold takes a long time on a heat pump.
Do children need it warmer?
Generally yes. They generate less heat, cool faster, and will simply refuse to use a pool they find unpleasant, which defeats the purpose of having one.
Can a pool be too warm?
Yes. In tropical Australia pools can become uncomfortably warm at the peak of summer, which is why reversible units that can cool are a genuine feature rather than a novelty.
Work out your number properly
The right setpoint depends on your household, and what it costs depends on your pool, your climate and your cover.
Request a free personalised pool heat report, read the complete pool heater guide, or browse the pool heater range.
