Seasonal care

How to winterize
your pool

By Dominik Graham PritchettUpdated 30 September 2026About 9 min read

Putting a cover on the pool is not enough. To prevent frost damage to pipes, the pump and fittings, prepare the water, equipment and cover as one system. Here is a safe order of work – without applying a winter plan that does not fit your pool.

First decide: store, active winterization or passive winterization?

There is no one correct winter setting. It depends on what your pool and equipment were designed for.

• Seasonal above-ground and quick-up pools: Many models should be completely drained, dried and stored. Check the manual first.
• Winter-proof above-ground and in-ground pools: These can often remain filled with water when fittings, pipes and equipment are protected correctly.
• Active winterization: The system continues to run under a dedicated frost-protection plan. Use this only where the equipment and controller are designed for it.

If you are unsure which method your pool permits, follow the manufacturer documentation or use a qualified pool professional. A one-size-fits-all method is especially risky with heat pumps, salt systems, counter-current units or fixed pipework.

When should you winterize your pool?

Do not wait for the first frost. Prepare the pool once the swim season is over, the water temperature is steadily falling and frost is foreseeable. Depending on the manufacturer, passive winterization commonly begins at a sustained water temperature of around 12–15 °C. At warmer temperatures, algae and deposits can still develop under the cover.

Winterizing by pool type

The pool type decides whether water stays in the pool and how much. The table gives a rough guide; for more on your type of pool, see above-ground pools and permanent pools.

The safe order for winterizing

Before you start: note your pool model, filter system, heater and any special equipment such as a salt system or fittings, and check the manual for the specified winter position, plugs and water level. Then work through these seven steps – the same ones used by the checklist in the app.

1. 1Final thorough clean
   Remove leaves, dirt and deposits from the waterline, walls and floor, vacuum the pool and empty the skimmer basket. Whatever stays in the pool in autumn makes the spring start unnecessarily hard.
2. 2Set pH to 7.0–7.4
   A balanced pH protects the pool material, seals and metal parts from corrosion and scale over the winter. How to correct it is covered in the guide Pool pH level. Keep free chlorine in the normal range: 0.3–1.5 mg/l without cyanuric acid, 1.0–3.0 mg/l with cyanuric acid. Do not shock-chlorinate immediately before passive winterization: chlorine breaks down slowly under a cover. Add care or winter products only as the product label directs, and run the circulation for as long as the manufacturer specifies.
3. 3Lower the water level
   Lower the water only to the level specified for your pool: for permanent pools, below the skimmer and return jets, often at least about 10 cm below the lowest fitting; for above-ground pools, as stated in the manual. Many above-ground pools are emptied completely over winter and stored dry.
4. 4Winterize the equipment
   No water may remain in frost-exposed components. Backwash the filter thoroughly or clean it, and drain pipes, pump, hoses, valves, heat pump and extra equipment as directed. Open only the drain points provided for this and store removable devices dry and frost-free. Details on individual devices follow below.
5. 5Add winter chemicals (if water stays in the pool)
   For pools that overwinter with water, add a winterizing or algae-protection product as directed by the manufacturer. For above-ground pools that are drained completely, this step does not apply. Remember: the product protects the water, not the equipment.
6. 6Secure accessories
   Take ladders, robots, thermometers, hoses and loose accessories out of the pool and remove the skimmer basket. Close skimmers, return jets and other openings with suitable winter plugs, depending on your system, so that no water freezes in the pipes. Clean and dry everything before storing it to avoid frost, rust and material damage.
7. 7Cover the pool
   Use ice-compensation floats only where they are intended for your pool, then fit the correct winter cover as instructed, taut and secured on above-ground pools. Check the fastenings and drainage, and watch for snow load. A cover is not automatically a child-safety device: secure access separately and, for above-ground pools, remove the ladder if appropriate.

Water level when winterizing

On a permanent pool, use the lowest fitting as your reference, usually the skimmer or a return jet. In winter the waterline sits below it, so freezing water cannot burst the connections. The openings are closed with winter plugs.

Equipment in detail

For these devices it is worth checking the individual manual, because the procedure and winter position differ by manufacturer.

Salt system

Remove the cell or electrode as directed, clean it and store it dry.

Sand filter

Backwash the filter, set the multiport valve to the winter position specified by the manufacturer and drain the tank.

Cartridge filter

Clean the cartridge and let it dry thoroughly, or replace it. Then drain the housing.

Heat pump

Drain the unit as directed in the manual. Residual water in water-carrying components can cause damage in frost.

Pool robot

Clean the robot and its filter basket, dry it and store it frost-free. Store the battery partly charged, as the manufacturer advises.

Storing pool chemicals and test equipment safely

Pool chemicals

• Store them dry, frost-free and cool.
• Keep them in the original packaging so the contents and safety information stay identifiable.
• Keep chlorine and acid products apart and never store or mix them together.
• Lock them away, out of reach of children and pets.

Test equipment and reagents

• Photometer: Remove the batteries so they cannot leak.
• pH electrode: Store it moist in storage solution, not dry, and keep it frost-free.
• Reagents and test strips: Check the expiry date. Expired products give unreliable readings, so replace them in spring.

Check occasionally throughout winter

A passively winterized pool needs little work, not no attention. After storms, heavy rain or snow, check the cover, its fastenings and the water level. With active winterization, the pump and frost-protection system must be monitored as part of the plan.

Common mistakes

• Starting too late: above-ground equipment can be at risk before the pool freezes.
• Guessing the water level: pools are not all drained to the same height.
• Draining only the pump: pipes, valves and other devices can retain water too.
• Confusing winter chemicals with antifreeze: water treatment does not protect equipment from frozen water.
• Treating the cover as a safety barrier: an ordinary winter cover does not secure access.
• Forgetting chemicals and test equipment: frost and moisture ruin chemicals, electrodes and test strips.

In spring: the start of the season

When the season begins, you also come back in steps: visual inspection, clean or replace the filter, top up the water level, clear the skimmer and jets and remove the winter plugs, retest all values and then let the system run for 48 hours. In Pool Buddy the reactivation checklist takes care of this: as soon as you put a winterized pool back into operation in the pool details, it guides you through these steps and the care tasks start again. Open reactivation checklist

If the water is green or cloudy after winter, the guides Green water and Cloudy water will help.

Frequently asked questions about winterizing

Technical orientation: BAYROL and Steinbach, accessed 2 September 2026. The instructions for your own installed products remain authoritative.