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Every autumn the same argument happens: shut it down or keep it turning. The answer depends on where you live, and the cost of getting it wrong is very lopsided.
If your pipes can freeze, close it
Water expands when it freezes. In a pool that means cracked pump housings, split heaters, burst underground plumbing and, in bad cases, damage to the shell. All of it is far more expensive than the cost of a winterising service.
Closing properly is a specific list, and the order matters:
- Balance the water first, so it does not sit corrosive or scaling for months.
- Clean it thoroughly. Anything organic left in the water is a spring problem.
- Lower the water level to the point the closing method requires.
- Blow out the lines and plug them, or use antifreeze rated for pools.
- Drain the pump, filter, heater and chlorinator. Every component that holds water.
- Add winterising chemicals and cover it.
If you are not confident about the blow-out step, pay someone. That is the step that breaks things.
If it never freezes, do the arithmetic
In a mild climate the comparison is:
Running through winter: reduced pump hours at low speed, a smaller chemical load in cold water, no heating, and a pool that is usable on a warm day.
Closing: the closing service or your own time, the opening service in spring, and the risk of a chemistry problem in water that sat still for months.
Two things usually decide it. The first is how mild the winter actually is, because cold water needs much less chlorine and much less circulation. The second is whether you will genuinely swim: a pool held ready for a warm February afternoon that never happens is an expensive option.
Drowning risk does not stop when the pool is closed. A floating winter cover is not a barrier: it can hold water on top and it can be walked onto. The fence and the gate latch are what protect a child in February, exactly as they do in July.
The middle path most mild-climate owners land on
- Drop the pump hours, keep circulation daily.
- Hold a lower but real sanitiser level, and test weekly rather than daily.
- Leave the heater off and covered.
- Keep the cover on, which reduces debris, evaporation and chemical use.
- Check the water level and the cover after storms.
What a closed pool still needs
Even properly closed, look at it monthly. Clear standing water off the cover, because it is both a load and a mosquito breeding site. Check that the cover is still anchored. After a heavy freeze, confirm nothing has shifted. Ten minutes a month prevents the spring surprise.
Related reading: Should You Buy a House That Has a Pool? and A Hot Tub Cover Purchase Needs Fit and Safe Handling.
Questions people ask
Is it cheaper to close a pool or keep it running?
In a climate with hard freezes, closing is not optional, because freeze damage costs far more than either option. In a mild climate, compare reduced winter running costs against the price of closing and opening.
Can I leave the pool uncovered over winter?
You can, but it means more debris, more evaporation, more chemicals and a longer spring clean. Standing stagnant water also becomes a mosquito problem.
Do I still need the fence in winter?
Yes. A winter cover is not a safety barrier. The fence and self-latching gate are what keep working when the pool is not in use.
How low should the water level go?
It depends on the closing method and the cover type, so follow the instructions for yours. Too low can damage some covers and liners, and too high can freeze in the skimmer.
Where these figures come from
- Safety Barrier Guidelines for Residential Pools US Consumer Product Safety Commission, Pool Safely · poolsafely.gov
- Water Savings in Pools and Spas Building America Solution Center, US Department of Energy · basc.pnnl.gov
Figures last checked September 2026.
