Kids jump into a swimming pool.

How to Winterize a Swimming Pool

It’s about that time of year that we have to start packing up all of our fun summertime toys and preparing for winter. You spent all Spring and summer ensuring your swimming pool was in tip-top shape, so don’t ruin all that hard work by not properly getting it ready for winter storage. 

Winterizing your pool will prevent damage to its frame and imbalanced water. It’s time to think about winterizing your pool when temperatures are consistently lower than 65 degrees. Our guide will make it easy to learn how to winterize an above-ground pool or an inground pool.

How to Winterize Your Pool

Winterizing an above-ground pool and an inground pool are nearly identical processes. The main difference is an inground pool is usually directly attached to your plumbing system. This requires the plumbing and skimmer lines to be blown out using either a blower or wet/dry vac. Also, the filter valve should be set between any two settings, so the ports are partially open to allow for freeze expansion. 

Tools and Materials


  • Skimmer and Brush
  • Pool Vacuum
  • Blower or Wet/Dry Vac (for inground pools)
  • Blowout Extension (for inground pools)
  • Leaf Net
  • Winter Pool Cover


  • Pool Schock
  • Algaecide
  • Winter Plugs
  • Skimmer Plug
  • Air Pillows
  • Test Strips or Test Kit

Test and Balance Water

Pool water test kit sits next to a swimming pool.

Before you do anything else, be sure you balance the water in your pool. You can use test strips or an at-home pool test kit which are sold at most large hardware stores. This optimizes the effectiveness of any winterizing chemicals added to the water. Focus on balancing the alkalinity, pH, and total hardness of the pool’s water. Ideal levels are:

  • Alkalinity: 80-120 ppm
  • pH: 7.2-7.6
  • Total Hardness: 180-220 ppm

If the alkalinity or hardness is too low, add increasers to bring them back up. Increasers or reducers can be used to level the pH of the water. Keeping a proper balance of your water helps prevent scaling, which is calcium buildup that appears on your pool walls.

Clean the Pool

A skimmer net is used to remove leaves floating on the surface of a swimming pool.

Once you’ve optimized the chemical balance of your pool water, it’s time to clean the pool. This is one of the most pivotal steps as it prevents algae from growing and creating a larger headache in the Spring. Algae can also stain the interior of the pool, making it unsightly.

Begin by using a skimmer or leaf net to remove any debris floating on the surface of the water. If debris is left in the pool, it will counteract any winterizing chemicals you add to the water. Then use a brush to scrub the sides and bottom of the pool. If you have one, a pool vacuum is an excellent option to clean the bottom of the pool after scrubbing as it will suck up any debris you just removed from the walls and floor.

Add Winterizing Chemicals

Chemicals are added to a swimming pool.

Now that your water is as perfect as you can get it, it’s time to add the chemicals that will preserve that balance through the winter season and eradicate any last contaminants. You’ll need pool shock and algaecide for this step. Pool shock does exactly what the name says. It quickly destroys bacteria, algae, and other waste matter with a high dose of chemicals. The algaecide is an additional measure on the top of the shock to prevent any further algae from growing.

First, add the shock according to the guidelines on the packaging. This will remove contaminants and increase the chlorine residual, which kills bacteria. Be sure you buy a quality brand of shock so it won’t affect the water’s pH level or hardness you’ve already balanced. Run your pump system for 4-5 hours after administering the shock to help circulate the product throughout the water.

Second, add the algaecide according to the packaging guidelines. Be sure to pick an option that won’t cause surface staining within the pool. After application, let the pump system run for another 24 hours to circulate the product throughout the pool. Algae occurs from spores being blown into the pool. The algaecide will prevent colonies from forming.

Remove Accessories and Filters

You’re in the home stretch now. It’s time to remove any accessories, filters, and skimmers. 

A filter from a swimming pool is removed to be cleaned.
  • Start by cleaning your pool filter. You can either backwash the sand or DE filter or manually clean the filter if it’s a cartridge filter. If it’s a cartridge filter, remove and store the cartridges.
  • Remove the skimmer basket, return fittings, pool cleaners, and ladders. Basically, remove anything that isn’t attached to the frame. 
  • Next, you can plug the skimmer with a skimmer plug, or you can lower the water level to about 3-inches below the skimmer. 
  • NOTE: Do not completely remove all the water from your pool. That could lead to the pool walls collapsing in on themselves.

Drain Equipment and Pipes

Water is drained from the plumbing of an inground swimming pool.

One of the last steps is completely draining any equipment or pipes of water, so they don’t become damaged or grow mold inside them. Begin by turning off all power to any pool equipment. Remove the return line and skimmer hose and completely drain them. If you have PVC pipe, use a blower with an extension or a wet/dry vac to blow the water out of the pipes.

After removing all hoses, you need to drain and store all filtering, pumping, heating, and chlorinating equipment. Finally, plug any holes from drains and equipment with winter plugs so water doesn’t get inside them during the winter. Remove the eyeball fitting on your return line and replace it with a winter return plug.

Final Steps

A cover over an inground swimming pool during winter.

The last few steps are the easiest. You’ll be installing air pillows and the pool cover. Air pillows cause water to expand toward them in the center of the pool when it freezes instead of outward and causes the structure of your pool to become stress. Inflate the pillows and attach them to a stationary object. You’ll need 2-3 pillows for an average-sized pool, typically 16 feet by 32 feet. 

Lastly, install the pool cover. Most above-ground pool covers include a winch and cable to secure the pool cover. Several accessories are available to help keep the cover secure over the winter, such as wall bags or cover clips. These options are great for areas with high winds. If you’re installing a cover on an inground pool, be sure it’s properly sized and lay over the top of the pool. Water bags or winter cover blocks can be placed around the edge of the cover to ensure it stays in place. Bags should be placed 18 inches apart, and in windy areas, they should be placed end-to-end. You can install a leaf net over the top of the cover if you like, but it isn’t required. A leaf net will make it easier in the Spring when you need to remove any fallen leaves quickly from on top of the cover.

You’ve finished the steps to winterize your pool. I’m sure it seemed daunting at first, but now you’ve saved money doing it yourself. Now curl up in front of the fire as you wait for Spring to roll around so you can re-open your pool.

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