How to Close an In-Ground Pool for Winter
Published
Quick answer
A winter closing is a system-protection job, not simply putting on a cover. Clean and balance the pool first, then follow the exact equipment and plumbing winterization procedure for the installation. In freeze climates, the most consequential work is getting water out of, or safely protected within, vulnerable equipment and lines. If you cannot verify that step, hire a pool professional.
Safety
Never open a pressurized filter, work on energized pool equipment, or improvise compressed-air plumbing procedures. Incorrect winterization can damage plumbing, pumps, filters, heaters, salt systems, and other equipment.
1. Clean before you close
Remove leaves and debris, brush surfaces, vacuum as needed, empty baskets, and make sure the pool is free of an active algae problem. Debris left for months can stain surfaces and consume sanitizer.
2. Test and prepare the water
Test the pool before closing and correct meaningful water-balance problems using product labels and system guidance. Do not assume a generic closing kit replaces accurate testing. If a winterization product is used, verify that it is compatible with the sanitizer, surface, cover, and other products already in the water.
3. Remove seasonal accessories
Remove cleaners, detachable fittings, ladders, and other items that the pool or equipment manufacturer says should not remain in winter conditions. Clean and dry stored equipment before putting it away.
4. Protect the equipment pad
Pumps, filters, heaters, chlorinators, salt cells, and automation components have model-specific winterization instructions. Drain plugs, unions, valves, air-relief procedures, and storage requirements differ. Use the manuals for the installed equipment rather than copying another pool's pad.
5. Protect freeze-prone plumbing
Pentair describes professional winterization as blowing water from pool lines and installing appropriate plugs or skimmer protection to reduce freeze damage. This is the part of closing where a mistake can turn into cracked underground plumbing or equipment. Use qualified help if the plumbing layout or air procedure is uncertain.
6. Set the water level only for your closing method
Some full winterization procedures lower water for freeze or overflow protection, but the correct level depends on pool construction, cover type, skimmer protection method, groundwater conditions, and professional guidance. Do not copy a fixed number of inches from a generic checklist.
7. Install and maintain the winter cover
Inspect the cover and anchoring system before installation. A solid cover may require water removal during the off-season, while mesh and safety-cover systems have different maintenance needs. Follow the cover manufacturer's instructions and keep the surrounding deck clear of hazards.
Document what you did
Take photos of valve positions, removed plugs, equipment settings, and stored parts. Label small components. A simple closing record makes spring reassembly safer and reduces the chance that a plug, gasket, or setting is forgotten.
What you may need
- Winter pool cover
- Pool cover pump if the cover requires one
- Winterizing plugs
- Skimmer protection device
- Water test kit
- Pool closing kit only if compatible and label-directed
Products mentioned in this guide
These are product categories referenced by the guide, not tested or ranked picks. Check the product description, your pool or equipment model, and the seller listing before buying.
Winter pool cover
Pool cover selected for the pool type, dimensions, anchoring method, weather exposure, and manufacturer installation requirements.
Places to check
Pool cover pump
Pump used to remove accumulated water from compatible solid pool covers. Follow the cover and pump instructions.
Places to check
Pool winterizing plugs
Model- and plumbing-size-specific plugs used as part of a proper winterization procedure. Match thread and fitting size before purchase.
Places to check
Skimmer winterizing plug or gizmo
Skimmer protection device selected to match the skimmer and the winterization procedure used for the pool.
Places to check
Comprehensive pool water test kit
A DPD/FAS-DPD style kit used to read chlorine, pH, alkalinity, stabilizer and hardness.
Places to check
Pool closing or winterizing kit
Bundled seasonal chemicals whose contents and concentrations vary. Use only products compatible with the pool system and follow each label.
Places to check
Related guides
- When Should You Close Your Pool for Winter?There is no universal closing date. Pools exposed to sustained freezing conditions need a real winterization plan, while many warm-climate pools can remain open or use a partial winter routine. Pentair advises winterization where snow, sleet, or temperatures around or below 32°F are a consistent part of winter, and its Sun Belt guidance describes year-round or partial operation in warmer climates. Use local freeze risk and the equipment manuals, not the first cool weekend, to decide.
- Pool Closing Mistakes That Create Expensive Spring ProblemsThe most expensive closing mistakes happen when owners treat winterization as a cover installation instead of protection for an entire water-and-equipment system. The high-risk errors are closing with active algae or debris, guessing at chemistry, leaving freeze-prone water in equipment or plumbing, using mismatched plugs or fittings, choosing a water level without considering the pool and cover, and assuming the pool needs no attention until spring.
- How to Winterize an Above-Ground PoolAbove-ground winterization protects both the water system and the pool structure. Clean and balance the pool, remove equipment and accessories that should be stored, follow the pump/filter/plumbing manuals, protect the skimmer and return fittings according to the pool's winterization method, and install a cover intended for that pool. Do not drain an above-ground pool simply because winter is coming unless the pool manufacturer specifically directs it.
- What Chemicals Do You Need to Close a Pool?There is no universal list of chemicals that every pool must receive at closing. Test the water first, correct meaningful balance or sanitation problems, and then use only winterization products that are compatible with the pool surface, sanitizer, cover, and equipment. Pentair's current winterization guidance tells owners to balance the water and shock before adding winterization chemicals, but the exact products and doses still come from the measured water conditions and each product label. A bundled closing kit is a convenience, not a substitute for testing.
- Should You Lower the Water When Closing a Pool?Sometimes, but not by one universal number. Pentair's full winterization guidance says lowering water can help with freeze and overflow protection, while its Sun Belt partial-closure guidance explicitly says not to lower the water because circulation continues through the skimmers. The correct level depends on whether the pool is fully winterized or kept circulating, the cover, skimmer-protection method, pool construction, groundwater conditions, and local professional guidance.
- How to Winterize a Pool PumpA pool pump is winterized by preventing freeze-prone water from remaining trapped in the pump and connected plumbing. Shut the equipment down safely, follow the exact pump manual for drain plugs, pot/lid position, unions and storage, and winterize the suction/return lines as a separate plumbing task. Pentair's current winter guidance specifically references removing pump pot and volute drain plugs during severe winter conditions. Do not run a pump dry as a substitute for draining it.
- How to Winterize a Pool FilterWinterize the installed filter model, not a generic “filter.” Shut the pump off, relieve all vessel pressure through the manual air-relief procedure, and drain the filter using the model's specified drain points. Cartridge, sand and DE filters use different internal media and service procedures. Pentair's current filter safety guidance emphasizes pressure relief before service, and several Pentair filter families include dedicated drains specifically for service and winterization.
- Pool Closing Supplies Checklist: What You Actually NeedBuy supplies from the closing plan, not the other way around. Most owners need water-testing and cleaning supplies, an appropriate winter cover, and model/plumbing-specific items for the chosen winterization method. Freeze-climate closures may also require skimmer protection, line plugs and equipment drain parts. Above-ground cover systems may use an air pillow. Chemicals depend on measured water conditions and product compatibility. Do not buy a giant kit first and then invent reasons to use every item in it.
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General reference information for pool owners. It is not a substitute for your equipment manuals, product labels, or a qualified local pool professional. Read our editorial standards.