Don’t Drain Your Pool!: Thoughts on The Costco Connection’s Recent Article

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With the number of cases of water and Gatorade our crew consumes on a regular basis, we at Ask the Pool Guy are regulars at our local Costco. We also love their magazine, The Costco Connection, which often has helpful time- and money-saving tips. In the July issue, they featured an article about saving money by doing your own swimming pool maintenance. Most of the article was really helpful, and we totally support people taking ownership of their pools and learning how to maintain and even repair their swimming pools. After all, that was the original idea behind Ask the Pool Guy: sharing quality information with swimming pool owners around the country, so every pool can be properly cared for. Once you get the hang of it, swimming pool maintenance isn’t too complicated; and there are even plenty of repairs that can be made on your own if you have an understanding of the way your equipment works.

 A printed warning from Latham, parent company of Kafko, who manufactures our swimming pool liners.

A printed warning from Latham, parent company of Kafko, who manufactures our swimming pool liners.

We did find one major problem with Costco’s article, though. We were tracking with them and nodding along, until we got to the very end. In the sidebar headed “Pool School” (p. 69), there are daily, weekly, and “annually or as needed” tasks. The daily and weekly tasks were spot on, and most of the annual tasks are great. However, one of these tips says you should “drain your pool, thoroughly clean it and replace with fresh water.” This is absolutely not the case. We’ve said it before, and we’ll say it again here: you should NEVER drain your swimming pool, unless you are under the supervision of a swimming pool professional and have a good reason for doing so. Hint: a thorough cleaning is not one of those good reasons.

A vinyl liner pool which was drained in order to be cleaned.
A vinyl liner pool which was drained in order to be cleaned.

Here’s the thing: draining your swimming pool yourself will immediately void any warranty you might have on your pool, and it poses significant risks no matter what type of pool you have. If you have a vinyl liner, draining your pool will ruin the liner. A vinyl liner is, in essence, a big bag that holds water. The water in your pool is what holds the liner in place–remove the water, and the liner will come out of place. This will usually require a liner replacement, which typically costs about $3,000-$4,000. If you have a fiberglass or gunite swimming pool, you’ll risk a pop-out. This is an incredibly expensive problem; the repair for this issue often costs more than it would cost to install a new pool. The reason for a pop-out is groundwater. A fiberglass pool is, essentially, a giant bathtub. It is all one piece, set into the ground in your backyard. The pool relies on the pressure of the water inside of it to be greater than the pressure of the groundwater. When the pool is full, this is no problem. The water inside of the pool presses down with enough pressure to overcome the pressure of the groundwater, and the pool stays in the ground. however, when the swimming pool is drained, there is no longer any pressure inside of the pool; this makes it easy for the pressure of the groundwater to push the pool out of the ground. A gunite pool works in much the same way–although it is a bit heavier, so the groundwater pressure needs to be greater in order to cause a pop-out. Regardless of your pool type, though, you should never drain your swimming pool…are you starting to see why?

A fiberglass pool that popped out of the ground after sitting empty.
A fiberglass pool that popped out of the ground after sitting empty.

If you are keeping up with the regular maintenance suggested in Costco magazine and on our website, you should not need to drain your swimming pool in order to thoroughly clean it. If you keep your water chemistry stable and at the proper levels, regularly vacuum and brush down the walls and bottom of your pool, and run your filtration at least 8 hours per day, there should be no need for you to drain your pool annually or at any other time. Occasionally, a gunite pool may need an acid wash. This is a kind of deep-cleaning procedure in which the pool is drained, the surfaces washed down with acid to remove the top layer of concrete, and the pool is refilled. This should only be done under the supervision of a trained professional, and it should never take longer than one day. This is a very occasional procedure and can be harmful to the pool if performed too often. If you have significant and persistent algae problems, or significant staining in your swimming pool, you could benefit from an acid wash. But, again, this is a project that must be done with great care and efficiency.