Maintenance

How to winterise your pool? The step-by-step guide

Winterising your pool properly means protecting it from frost and finding it clear and healthy in spring, with no hassle. Here is the method.

Updated in June 2026 · 6 min read

In Switzerland, winter frost can damage a poorly prepared pool: pipework, skimmers, plant room. Winterising prevents this damage and reduces the work of getting the pool running again. Two methods exist; let's see which to choose, then the steps.

Active or passive winterising: which to choose?

Passive winterising means shutting the pool down completely: you lower the water level, drain the circuits and cover the pool. This is the recommended solution in regions where it freezes for long periods, such as much of Switzerland.

Active winterising keeps the filtration running on a low setting to stop the water from freezing. It suits mild winters or pools fitted with frost-protection control, but uses a little electricity.

When to winterise?

The right time is when the water temperature drops steadily below 12 °C, usually in autumn. Too early, and algae can still proliferate; too late, and you risk frost. Below 12 °C, micro-organisms are dormant: this is ideal.

The steps of passive winterising

Clean the pool: run the robot, brush the walls and empty the skimmer baskets.
Balance the water: adjust the pH and carry out a shock treatment to start with healthy water.
Lower the water level below the skimmers and the return jets.
Drain the circuits and the plant room (pump, filter, pipework) so that no water freezes.
Add a winterising product that prevents algae and deposits during the cold season.
Fit anti-freeze accessories (floats, gizzmos) to absorb the pressure of the ice.
Cover the pool with a winter cover, a slatted cover or an enclosure to protect it from leaves and debris.

Automatic slatted cover over a pool — A slatted cover or an enclosure protects the pool all winter and simplifies winterising.

And during the winter?

A winterised pool requires little monitoring: regularly remove the leaves and snow that build up on the cover, and check that the water level stays correct. A solid cover (slatted cover or enclosure) makes this period considerably easier.

Have it done with complete peace of mind

Winterising is a technical task: a mistake can prove costly in spring. Our maintenance contracts include winterising (and reopening), with a guaranteed intervention and professional follow-up. You enjoy your pool; we take care of the rest.

At what temperature should you winterise your pool?

When the water drops steadily below 12 °C. Below this, algae and bacteria are dormant: it is the ideal moment to lock in healthy water.

Should you empty the pool completely in winter?

No, definitely not. You simply lower the level below the skimmers. Emptying a pool entirely can damage it (ground pressure, a fibreglass pool lifting) and is not necessary.

Active or passive winterising in Switzerland?

In most regions of Switzerland where it freezes for long periods, passive winterising is recommended. Active winterising suits mild winters or setups with frost-protection control.

What happens if you don't winterise?

Frost can crack the pipework and damage the pump, the filter and the fittings. Getting the pool running again is then longer and more expensive. Winterising is cheap insurance.

Want to stop dealing with it yourself?

Leave the winterising and maintenance of your pool to our teams. Winterising guaranteed, staged payment possible.

See our maintenance contracts