When temperatures drop and days get shorter, it’s time to think about winterising your swimming pool.
Doing it correctly protects your investment, prevents damage, and makes spring opening far easier. Without proper preparation, cold weather can crack pipes, stain surfaces, and leave water unsafe to swim in once the warmer months return.
If you’d prefer a trusted expert to handle the process, we offer a cost-effective Winter Pool Care & Servicing Package, covering cleaning, chemical balancing, equipment checks, and cover inspection, so your pool is ready for the next swimming season.
This guide will help you close your pool with confidence and keep it in top condition throughout the colder months.
When to Start Winterising Your Pool
In the UK, most swimming pool owners begin winter maintenance once the water temperature drops consistently below 12–15°C and the leaves really start falling. At that point, algae growth slows and your sanitiser can hold steady for longer. You’re aiming to close on a calm, dry day so you can work methodically around the pool deck, equipment pad, and cover without rushing.
Step-by-Step Winterising Guide
Step 1: Deep Clean the Water and Surfaces
Don’t pack things away while there’s still leaf litter at the bottom. Skim the surface, vacuum the floor, and give the walls and steps a firm brush. This stops stains from setting in and keeps any leftover algae from causing trouble while the pool is covered.
Step 2: Test and Balance Your Chemistry
Getting your pH level, alkalinity, and calcium hardness right now saves a lot of headaches later. Unbalanced water over winter can nibble at your liner or leave white scale along the waterline.
Aim for your normal mid-season levels, and if you’re unsure, book a professional water test with us and we’ll check it’s spot on before you shut things down.
Step 3: Shock the Pool and Add a Winter Algaecide
Think of this as giving the water a deep clean before it hibernates. A good oxidising shock treatment followed by a winter algaecide helps keep the pool clean and clear under the winter cover
Before covering your pool, run the pump and add a shock treatment to clear out leftover oils, sunscreen, and combined chlorine. Once circulated, add a winter algaecide to stop algae from growing in cold, still water. Follow the label for the right dose and your pool will remain clear and easier to reopen in spring.
Step 4: Clean and Service Your Filter
Your filter has worked hard all season, so now’s the time to help it rest.
Backwash sand filters, hose down cartridges, or get a DE filter cleaned and topped up. A clean filter means no unpleasant build-up sitting there all winter. We can include this as part of a Hydrocare winter service if you’d rather leave it to us.
Step 5: Drop the Water Level a Touch
Lower the water line just below the skimmer to keep freezing and rainwater from creeping into places it shouldn’t.
Don’t go too low, as you still want enough weight to hold the liner and keep the cover stable. Not sure how far to drain? We can advise based on your pool type and finish.
Step 6: Protect Pipes and Equipment From Ice
Frozen water is the enemy. Where possible, blow out pipework with a suitable blower and fit winterising plugs. In exposed setups, use pool-safe antifreeze in the lines as extra protection. Open drain plugs on the pool pump, heater, and filter to let any trapped water out.
If that sounds technical, our pool technicians can help you handle it.
Step 7: Check the Equipment Area
Give your pump housing a wipe, clear debris from the heater, and switch off timers or circuits not needed over the winter period.
If you’ve got a control panel or automation system, set it for off-season mode or call us if you’re unsure.
Step 8: Secure the Winter Cover
A strong winter pool cover is your swimming pool’s winter coat. Stretch it tight, fasten straps or water bags, and check the edges for gaps. This keeps sunlight out and stops leaves and insects from making themselves at home.
Getting the fit right really matters, so it’s important to have a cover that fits the exact shape of your pool.
Step 9: Final Checks
Once everything’s snug, walk the pool edge slowly. Remove ladders, check railings, and look for anything sharp that might rub the cover.
Snap a quick photo of your pool’s chemical readings and water level, as it’s handy for spring when you’re ready to open again.
Common Winterising Mistakes to Avoid
Even with the best intentions, some simple oversights can cause big problems once temperatures drop. Keep an eye out for these common mistakes when closing your pool for winter:
- Leaving debris in the water: organic matter breaks down and can stain liners and grout.
- Skipping proper balance: unbalanced pool water can etch tiles, fade liners, and corrode metal fixtures.
- Neglecting the filter: a dirty filter strains on opening and may push fine dust back into the pool.
- Loose or damaged covers: gaps invite leaves, insects, and light that fuels algae.
- Forgetting to drain equipment: trapped water in a pump volute, heater exchanger, or multiport valve can freeze and crack components.
Ongoing Winter Checks
Even with the pool closed, a little attention pays off. Every few weeks during the winter months, look over the cover tension and remove standing water from solid covers with a cover pump. Inspect straps, anchors, and water bags for movement after storms.
If you can safely access a test point, a quick mid-winter water test helps you make small adjustments that save time in spring.
How Professional Help from Hydrocare Makes This Easier
Closing a swimming pool correctly takes time, experience, and the right pool equipment. That’s where our Winter Pool Care & Servicing Package comes in.
Our winter pool care isn’t just about shutting things down; it’s about protecting your outdoor pool for the long months ahead and making reopening smooth and cost-effective. Whether you have an above-ground pool, an in-ground pool, or even hot tubs and spas that need safe winter shutdown, we understand the different needs of each setup and tailor the service accordingly.
With this package, our team will:
- Check all key equipment, including the pump, heater, and filtration system, so nothing suffers unnoticed wear or damage over winter.
- Thoroughly clean the pool, skimming and brushing to stop stains and build-up.
- Balance water chemistry with the right sanitiser, pH, and winter algaecide, preventing algae and bacteria from taking hold.
- Reduce the water level to a safe winter depth and make sure pipework is protected from freezing.
- Inspect and fit your winter cover, ensuring it’s secure and debris-proof.
For many owners, we also recommend monthly winter check-ups to make sure the cover stays tight, the water chemistry doesn’t slip, and the equipment remains protected. This small step can save major repair bills and make spring opening faster and cheaper.
Learn more about our winter service
Quick Pool Winterising Checklist
- Deep clean completed (skim, vacuum, brush)
- Chemistry balanced (pH, TA, CH, sanitiser)
- Shock applied and winter algaecide added
- Filter cleaned or backwashed
- Water level lowered below the skimmer
- Lines blown and plugged; antifreeze used if needed
- Equipment drained (pump, filter, heater, chlorinator)
- Winter cover fitted, tensioned, and checked
- Final inspection and notes recorded
Ready for Spring, With Less Work
Closing your swimming pool with care means opening with a smile. When the days warm up, you’ll remove the cover to clearer water, a cleaner filter, and equipment that’s ready to run.
If you’d like a hand at any stage of winterising your pool, from a pre-close water test to a full Hydrocare Winter Service, our team is here to help and set you up for a quick, easy start next season.
Just give us a call on 01444 236578 or email us at enquiries@hydrocare.co.uk.
