How to Winterize Your Pool: A Step-by-Step Guide

Closing your pool for the season is more than just throwing a tarp over the water and heading inside for hot cocoa. If you want to avoid cracked pipes, algae blooms, and expensive liner repairs, you need a solid winterization strategy. The good news? With a little preparation and the right sequence of steps, you can close your pool with confidence — and open it next spring without any nasty surprises.

In this guide, we’ll break down exactly how to winterize your pool to ensure it stays protected through the coldest months.

Clean the Pool Thoroughly

Before you even think about chemicals, you need a clean canvas. Any debris left in the pool over winter can cause staining and throw off your water chemistry. Organic matter like leaves and dirt breaks down slowly under a cover, feeding algae and creating stubborn stains that are a nightmare to remove come spring.

• Brush the walls and floor to loosen algae spores.
• Vacuum the pool floor, paying extra attention to corners and steps where debris tends to collect.
• Skim the surface to remove leaves and organic matter.
• Clean out your skimmer baskets and pump strainer basket completely.
• Give your pool tiles a good scrub along the waterline to remove any built-up calcium or scum before they sit all winter.

Pro Tip: If you notice any visible algae growth, treat it with a pool algae brush and a dose of algaecide before moving on to balancing your chemistry. Starting with a truly clean pool makes every subsequent step more effective.

Balance the Water Chemistry

About a week before you plan to close the pool, test your water. Balanced water protects your liner, equipment, and plumbing from corrosion and scale buildup — two issues that quietly cause damage all winter long. You want your levels to be within these ranges:

• pH: 7.2 – 7.6
• Alkalinity: 80 – 120 ppm
• Calcium Hardness: 180 – 220 ppm
• Free Chlorine: 1 – 3 ppm

Pro Tip: Add a winterizing chemical kit that includes an algaecide and a “winter float” to slowly release sanitizer over the next few months. If your pool has a history of algae problems, consider a double dose of algaecide and a phosphate remover to starve any remaining spores.

Allow the chemicals to circulate for at least 24–48 hours before moving on to the next steps. This gives the water time to fully stabilize before you shut everything down.

Shock the Pool

This step often gets skipped, but it’s one of the most important. Shocking your pool before closing it gives you a clean chemical baseline and wipes out any lingering bacteria or algae that balanced chemistry alone won’t catch.

• Use a non-chlorine shock or a standard chlorine shock at the recommended dosage for your pool size.
• Run the pump for at least 8 hours after shocking so it circulates thoroughly.
• Wait until your chlorine levels drop back down to 1–3 ppm before adding your algaecide, as high chlorine can deactivate it.

Shocking is essentially your “final wash” before the pool goes to sleep for the season.

Lower the Water Level

You’ll need to lower the water level to protect your skimmer and tiles from freezing water expansion. Water expands by about 9% when it freezes — enough force to crack a skimmer housing or pop tiles right off the wall.

• For Mesh Covers: Lower the water to about 12 inches below the skimmer.
• For Solid Covers: Lower it to about 6 inches below the skimmer.

Use a submersible pump or your pool’s backwash setting to bring the water level down efficiently. Avoid dropping it too low, as an empty or near-empty pool can cause an above-ground liner to collapse or an in-ground pool shell to shift from ground pressure.

Drain and Blow Out the Lines

This is the most critical step for those in freezing climates. Water left in the pipes can freeze, expand, and shatter your plumbing — and a burst pipe buried underground is one of the most expensive pool repairs you can face.

• Drain the pump, filter, and heater completely. Remove all drain plugs and store them somewhere you won’t forget — a zip-lock bag taped to the inside of your pump lid works great.
• Blow out the lines using a shop vac or specialized air compressor. Start from the skimmer lines, move through the main drain, and finish at the return jets. You’ll know each line is clear when you see bubbles erupting from the corresponding jet or fitting.
• Plug the return jets with expansion plugs and the skimmer mouth with a Gizzmo plug (a floating skimmer plug that absorbs ice expansion).
• If you have a pool heater, consult your manufacturer’s manual for specific winterizing steps — heaters often have additional drain points that are easy to miss.

Note for Saltwater Pools: Remove and store your salt cell before temperatures drop below freezing. Salt cells are expensive and can crack when exposed to ice. Clean it with a cell cleaning solution before storage to extend its lifespan.

Protect and Store Your Equipment

Your pump, filter, and other equipment deserve the same winterizing attention as your pipes. Taking a few extra minutes here can save you hundreds in equipment replacement costs.

• Pump: Once drained and blown out, store the pump indoors if possible — a garage or utility room is ideal.
• Filter: For sand filters, set the valve to “winterize” or remove it entirely. For cartridge filters, remove the cartridge, clean it thoroughly, and let it dry before storing.
• Heater: Double-check all drain plugs are out and the unit is fully clear of water.
• Ladders and Rails: Remove metal ladders and handrails, rinse them off, and store them indoors. This prevents corrosion and keeps them from damaging your liner if ice shifts under the cover.
• Accessories: Retrieve diving boards, floats, toys, and any other pool accessories. Leaving them out all winter degrades the materials and shortens their lifespan considerably.

Install the Winter Cover

Finally, it’s time for the “lid.” A properly installed cover is your pool’s primary defense against debris, UV exposure, and accidental falls throughout the winter months.

• Safety Covers: Check that the springs have proper tension and that all anchor points are secure. Safety covers are anchored into your deck and can support significant weight, making them the best option for households with children or pets.
• Standard Tarps: Use water bags to weigh down the edges, spacing them every few feet around the perimeter. Never use cinder blocks, as they can fall in and ruin your liner. Make sure there are no gaps where wind can catch under the cover.
• Mesh Covers: These allow rainwater to pass through while keeping debris out — great for areas with heavy precipitation. Just note they don’t block sunlight entirely, so maintaining algaecide levels is more important.

Whichever cover you choose, periodically check it throughout the winter after heavy snowfall or storms. Remove standing water from the top of solid covers using a cover pump — excessive pooling water can stretch and damage the material.

Do a Final Walkthrough

Before you call it done for the season, do one last check:

• All drain plugs are removed and stored.
• All return jets and skimmer openings are plugged.
• Your winter cover is secure with no gaps.
• Your chemical kit or winter float is in place under the cover.
• All equipment is stored or protected.

Taking five minutes for this final sweep can save you from discovering a preventable problem in the spring.

Conclusion

Learning how to winterize your pool correctly is an investment in your home. By taking these steps now — or by trusting the experts at Same Day Pool Cleaning — you save yourself hours of scrubbing and hundreds of dollars in chemical treatments when the weather warms up.

A well-closed pool is a pool that opens easily. Follow this checklist, document what chemicals you used and when, and you’ll be ready for a “clear water” reveal next spring without any headaches. The effort you put in today is the difference between a beautiful opening weekend and weeks of remediation work.