How to Properly Close Your Inground Pool for Winter

Closing your pool for winter could mean simply putting a cover over it and switching off the pump. Closing the pool properly involves winterizing it to avoid damage to the lining or shell of the pool and all the plumbing and equipment that is part of the filtration system. It applies to all pools, but in this article, I will concentrate on the detailed steps of closing and winterizing an inground pool for winter.

Closing inground pools for winter is recommended in areas with severe winters and freezing temperatures, and this would apply to most states except for the sunbelt in the south. Here, because there is less risk of freezing, it is possible, with care, to keep an inground pool open all year round.

My family, and I’m sure yours, too, make full use of the pool during summer, and it’s the center of many fun activities and get-togethers with friends. But come winter, although we’re lucky to avoid the freezing temperatures of most of the country, the pool and the weather are just too cold, so I close it with a 5-step winterizing to ensure it’s in great condition for the following summer. Here’s what I do – and it works!

5 Steps to Close An Inground Pool For Winter

There are several steps to follow in closing an inground pool, winterizing it, and making sure that it survives the sub-freezing temperatures without damage. A quick tip, though, before going into detail: don’t winterize too early. Wait until the daily temperature drops below 60⁰ F consistently so your pool doesn’t remain closed so long the chemicals lose their ability to prevent algae growth.

1. Clean The Pool And Remove All Accessories

You need to leave the pool absolutely free of any dirt or debris that will encourage mold or algae growth, so brush down the walls and floor and vacuum thoroughly. Once you’ve done this, clean your filter by backwashing and rinsing a sand or DE (diatomaceous earth) filter, washing cartridge filters, and cleaning the filter grids if your DE filter has them.

You will be covering the pool, so now’s the time to remove the ladder, automatic pool cleaner, baskets, and any non-essential equipment. This is a good time, too, to check all these items, service and clean them before you pack them away for the winter.

2. Check And Balance The Chemicals In The Water

As you’ve done all summer (I hope!), check the pool’s chemical levels and adjust if necessary. Ideal levels are:

  • pH: 7.2-7.8,
  • Total Alkalinity: 80-120 ppm
  • Calcium Hardness, 180-220 ppm and
  • Cyanuric Acid (Stabilizer): 30-50 ppm

You should do this check and adjustment a few days before closing the pool to ensure all the additives have been fully circulated. You may also want to add shock (not a fast-acting one, but one formulated for winterizing) and an algaecide just before closing.

3. Lower The Water Level

Because you won’t be running the pump, you don’t want water in the pipes or anywhere in the filtration system. You also don’t want to drain the pool any more than necessary, as the weight of the water helps to keep the pool firmly in position, particularly with fiberglass or vinyl-lined pools.

The correct amount to drain your pool depends on a number of factors, including the type of pool (concrete, vinyl-lined, or fiberglass) as well as the type of pool cover you’re using(solid, mesh, or safety cover.) I suggest draining the pool about six to eight inches below the skimmer box or two to four inches below the lowest jet.

If you lower the level too far, there’s a problem with the pool cover sagging and getting damaged as it collects debris, rainwater, or snow, but you can solve this issue by inserting a pool pillow in the center of the pool to support the cover.

Some experts feel it safer not to drop the water level but rather to plug the skimmer inlets. If the return outlets are also below the water line, you need to plug them as well to prevent water from flowing back into the system. I still recommend lowering the water level as the safest way of keeping the piping dry.

4. Blow Out The Pool Lines

This is a challenging part of closing the pool for winter. If you’re winterizing for the first time, getting a professional to carry out this task would be a good idea so that you can watch and learn for next year.

Essentially, it involves using an air compressor or large Shop Vac, connecting it to the main drain on the pump using an adaptor, ensuring that your multivalve is on recirculate, and then pumping air through the pipes until all or almost all the water has been expelled.

5. Covering The Pool

Fitting your pool cover is the final task in closing your pool for winter. Covers are available in various forms: Standard winter covers, which are the cheapest option, usually made from vinyl, will protect the pool from debris, leaves, and rain but won’t support the weight of heavy snow or of kids or pets who might venture on its surface.

Leaf Catcher Mesh Covers will allow rainwater or snow through into the pool but prevent debris from getting through. They are also not made to carry the weight of children or animals, but at least don’t hide them should they fall into the pool.

Solid or Mesh Safety Nets are designed to carry the weight of a person, are highly durable, and provide a barrier to debris, although the mesh will allow rain and snow into the pool.


What If I Don’t Close My Pool?

If you’re living in the sunbelt, where temperatures seldom drop below freezing, you may want to continue using your pool in late summer and even into fall. Especially if you have installed a pool heater, there’s no harm in keeping your pool running.

If, however, your pool is likely to freeze over in winter, and you haven’t winterized it and closed it, you could land up with burst inlet and outlet pipes, a cracked skimmer, and even a filter with a cracked housing. That will land you with a hefty repair bill, and it’s entirely avoidable by closing the pool down correctly.

Should I Add Antifreeze To The Water Before Closing The Pool?

This is optional, but I recommend antifreeze if you have severe cold for extended periods during winter. There is a specialized antifreeze for use in pools – don’t use the product made for your car radiator.


Closing an inground pool for winter is vital if you’re living in most of the country, where freezing weather conditions can easily result In burst pipes and severe damage. I’ve detailed five simple steps to winterizing and closing the pool, and following these will ensure that your pool is safe from water freezing in the filtration system and causing severe damage and will be sparkling and healthy come summertime.