How to Winterize a Pool

A pool ladder surrounded by ice in the water.
  • 4-6 hours
  • Beginner
  • 300-1,000

With summer over and winter fast approaching, it's time to start winterizing outdoor accessories. Preparing an outdoor pool for the cold winter will help prevent ice damage, ensure the water is kept clean, and make it easier to open the pool in the spring. Fortunately, winterizing a pool is a simple process that only takes a few simple steps to accomplish.

Step 1 - Remove the Debris

The pool will need to be free of any type of debris before starting the chemical process. Simply clean the area and make sure there are no leaves, insects, dirt, or other items in the pool. A pool vacuum makes this process less labor-intensive, but you can clean everything out with a good net. Don’t forget to check the skimmer and pump basket for clogs. It's also a good idea to clean the pool’s tile line now instead of waiting until the spring.

Step 2 - Balance the Water Chemistry

A hand holding a pool chemical testing apparatus over a pool.

With the pool clean of any debris, you want to balance the pH, alkalinity, calcium, and chlorination of the water. Refer to the pool manual for proper chemical levels. This will prevent scale buildup and corrosion that typically happens after the water has been sitting for long periods of time. Consider adding a winterization chemical kit to the pool that will increase the chlorine and algaecide levels in the water. Avoid using chemicals that might damage your pool and make sure to follow the instructions on the winterizing kit when adding chemicals.

Step 3 - Shock the Pool

High chlorine levels can ruin a winter cover. To avoid excessive chlorine levels, add algaecide to the pool according to the pool manufacturer.

Step 4 - Adjust the Water Levels

The biggest enemy of your pool is freezing water. Water expands when it drops below the freezing point. This expansion can cause serious damage to pipes, pumps, skimmer baskets, and filters. To avoid hazardous freezing, drain the water in your pool to the mouth of the skimmer. Keep some water in the pool to prevent it from dislodging if groundwater from below freezes. A little bit of weight will keep the pool in place throughout the winter.

Step 5 - Disconnect the Pump

For added protection against freezes, disconnect the filter and pump. Ensure that all the water is completely drained from the pump. Take off any drain plugs in the pump and turn it over to allow excess water to drain. If the pool is equipped with a heater, make sure it's free of any standing water. Also remove jet fittings, skimmer baskets, and pump baskets.

Step 6 - Flush out the Pipes

Disconnect any and all pipes from the pump and filter system. The goal is to extract all the water from the pipes in case of freezing temperatures. Use a shop vacuum or an air compressor to extract the water. Repeat the process for any return lines and the main drain line. Remember, water left in the lines will freeze and expand during winter, causing major damage to the component.

Step 7 - Clean the Filter

A close-up image of a pool filter.

Winter is a good time to give your filter a good cleaning. Disconnect all hoses and use a good filter cleaner to remove dirt and grime. Avoid acid washing the system because this process usually requires running pool water through the system. Once everything is clean and rinsed, drain all the water and close the valves.

Step 8 - Add a Flotation Device

Before installing a winter cover, consider placing a flotation device in the pool’s center. This device will balance any rainwater that accumulates on the cover and prevent unwanted pressure from building on pool walls. Without a floatation device, ice will put pressure against pool walls instead of the device.

Step 9 - Install a Pool Cover

The last step in winterizing a pool is to install a winter cover. A winter cover is more durable than a summer cover and is strong enough to take on the weight of ice and snow. A good winter cover will also prevent people and pets from crashing into the pool. Make sure the cover spans the entire area of the pool and that it's stretched tight across the surface. Repair any tears or rips before winter sets in and purchase a new cover if necessary.