Pool Closing Checklist for Winterizing Pools
A pool closing and winterizing checklist for freezing climates, with water prep, line blowouts, equipment drains and electrical and gas stop points.
Closing is a one-time job with long consequences. A line that still holds water freezes and cracks over winter, and the repair bill lands on whoever closed it. This page covers closing in climates where pools freeze. If you work in a region without freezing weather, many pools just stay open.
Before closing day
Do the prep a week or two ahead.
- Balance the water. Check pH, alkalinity, and calcium hardness so the water is neither scaling nor corrosive for months. See saturation index explained and aim for -0.3 to +0.3.
- Clean thoroughly. Brush, vacuum, empty baskets, and backwash or clean the filter.
- Chlorine and algae control. Bring free chlorine up to a level suited to CYA, then add winterizing products per their labels.
- Gather supplies. Plugs, gizmos, cover, cover clips or water bags, air blower, and a non-toxic pool antifreeze if the pool maker calls for it.
Always follow the product label and SDS. Add chemical to water and never mix products.
Closing day order
| Step | Task | Notes |
|---|---|---|
| 1 | Final test and dose | Add winterizing chemicals per the labels |
| 2 | Run the pump to circulate | Let it run long enough to mix the chemicals |
| 3 | Lower the water level | Level depends on cover type and the maker's guidance |
| 4 | Turn off power at the breaker | Before any draining or disassembly |
| 5 | Drain pump, filter, heater, and chlorinator | Remove drain plugs and store them in the basket |
| 6 | Blow out lines | Skimmer, returns, main drain, and any cleaner or spa lines |
| 7 | Plug lines | Use winter plugs or gizmos, and note each location |
| 8 | Add antifreeze | Only where the maker specifies, and only pool-safe antifreeze |
| 9 | Remove and store salt cell | Rinse and store indoors per the manual |
| 10 | Install cover | Secure it so wind and water do not get under it |
| 11 | Photos and report | Show the plugs, the level, and the cover |
Water level
How low to go depends on the cover and the pool. Mesh covers and solid covers often need different levels, and pools with tile or special features may need their own. Check the cover maker's or pool builder's instructions and follow them.
Do not drain a pool completely. In many in-ground pools, ground water pressure can lift or crack the structure when the pool is empty, and vinyl liners can shrink and tear. Ask the builder or manufacturer before you drain below the recommended level.
Blowing out lines
The goal is to remove water from the plumbing, so nothing freezes and cracks. A typical method:
- Power is off at the breaker.
- Set the valves so the blower pushes air through one line at a time.
- Connect the blower to the line at the pump or filter, depending on your setup.
- Run air until bubbles stop at the pool's fitting and the line appears empty.
- Plug the fitting at the pool while air is still flowing, so no water re-enters the line.
- Repeat for every line, including the main drain, spa lines, and the cleaner line.
If the pool has an automatic cover, a heater, in-floor cleaning, or a water feature, those parts may need their own steps. Follow the maker's manual.
A common mistake is plugging a line while water is still in it. Another is forgetting a line, such as a cleaner or spa return.
Equipment drain list
| Equipment | What to do |
|---|---|
| Pump | Remove drain plugs, drain the housing, store plugs in the basket |
| Filter | Drain, remove the pressure gauge if the maker advises, clean media or cartridge |
| Heater | Drain per the manual so the heat exchanger holds no water |
| Salt cell | Remove, rinse, and store per the manual |
| Chlorinator or feeder | Empty and drain |
| Valves and unions | Open or loosen drains as the manual says |
Stop points for electrical and gas
Turn the power off at the breaker before you drain, open, or remove any equipment. If the breaker is damaged, a GFCI fails to reset, wiring is damaged, or water is in a control box, stop and call a licensed electrician. Rules for who can do electrical work vary by state.
Gas heaters need their own care. Do not work on gas supply lines, valves, or burners. Drain the water side per the manual, and leave gas shutoffs and disconnections to a licensed professional. If you smell gas, leave the area and call your gas utility or 911 from a safe distance.
Cover and finishing
Set the cover so it fits without gaps. Secure it per the cover's instructions. If it uses water bags or blocks, fill and place them as directed. Tell the customer to keep the cover clear of heavy debris and to call you if water pools on it.
Take photos of the plugs, equipment, level, and cover. Put the locations of the plugs in the report so the opening tech finds them. See pool opening checklist.
Planning closing day
Say you have 60 accounts and can close five a day. That is 12 closing days, so the work spreads across several weeks. Start in the order the weather will end the season for each pool, and tell customers when to expect you with the customer message templates.
Mistakes to avoid
- Fully draining the pool. Ask first.
- Leaving water in a line. Blow out every line, and plug while air flows.
- Forgetting the heater or filter. Trapped water cracks them.
- Using automotive antifreeze. Use only pool-safe antifreeze, and only where the maker says to.
- Skipping water balance. Neglected water can scale or stain through winter.
- No photos. You cannot prove what was done.
Common questions
What is the first step in closing a pool for winter?
Balance and clean the water before anything else, so the pool does not sit through winter with scale, stains, or algae. Then lower the level, blow out lines, drain equipment, and cover.
Should I drain the pool when closing it?
Generally no. Lower the water to the level your cover and equipment require, but do not fully drain an in-ground pool without guidance. Check with the pool builder or manufacturer.
Do I need to blow out the lines?
In freezing climates, water left in plumbing can freeze and crack pipe, so lines are normally blown out and plugged. Follow the pool maker's and local professional practice, and check what applies in your area.