Does a swimming pool ever need to be drained and if so, how often should that be done?

Why might you need to drain your pool?

An average family swimming pool will contain somewhere between 18,000 and 20,000 gallons of water.

When a pool is drained that water just goes to waste and must later be replaced. There is an environmental cost and, if you are on a metered supply, a significant financial one. You will also have invested time and money in heating and treating that water, so draining your pool is not something to be undertaken lightly.

It is possible to minimise these costs, either by pumping the water into a temporary pool and then pumping it back after any work has been done, or by using a collapsible pillowtank for the same purpose.

There are two reasons that you might have to drain your pool. The first reason is to conduct repairs or refurbishment.

If you have an above-ground pool and for some reason the liner needs to be replaced then you have no choice but to drain.

If you have an in-ground pool and there is a structural problem with the shell or you want to re-mosaic your pool for instance then once again, draining your pool is the only option.

When a pool is drained for major refurbishment, refilling it with a hosepipe is excluded from any hosepipe ban regulations.

There are also some circumstances when you may have to drain your pool for water quality issues.

Draining your pool to improve the water quality.

The water in your pool today is, of course, not the water that was put in when your pool was first filled.

Water is lost through evaporation, through use where it is splashed out and through backwashing and that water loss is replaced when you top your pool up.

In the UK, if you have an outside pool, you will probably lower the water level when you winterise your pool and top up again at the start of the new season.

So over the course of time, the water in your pool is being replaced albeit a relatively small amount at a time.

Under normal conditions this may mean that you never have to completely drain and refill your pool.

However you may eventually find that it becomes increasingly difficult to balance the water in your pool and that sanitisers and filters no longer seem to be doing their job.

If this seems to be the case, then test your pool water or have a pool professional test the water.

What you are looking for is the TDS level (Total Dissolved Solids). If the level has become very high, perhaps a TDS reading of 1400, then there may be no option but to drain and start from fresh.

If you keep your pool water in consistently well-maintained condition, then this stage may never get reached.

Draining a pool for water quality issues is always a last resort and sometimes problems can be solved by dilution, which may mean draining the pool by a half and then topping up with fresh water. A pool professional would be able to advise you on this.

If you would like some specific advice on this subject and would like to find an appropriate pool professional in your area, there is a contact button to the right of this article that can get that process started.

If you would like to add a comment to this article then please use the reply box below.

We hope this article has been of use to you. There are many more articles on this site that will give you information on almost every aspect of your pool.


4 Responses to How often should I drain my swimming pool?
  1. I have a greenish yellow dusting on the bottom of my pool. I need to know who to contact and what to do.

    • Hi Elaine, Its quite likely that with the hotter, brighter weather we have been experiencing that you have harmless but unsightly Algae in your pool. The best and quickest way to get this looked at is to use the find a supplier button at the top right of this page and get in contact with one of our dealers nearest to you. Happy swimming.

  2. Should we drain are above ground pool ? The pool has not been taken care of in close to 2 years we just moved in and the water is black.Should we start fresh and empty it ?



    • Hi Robin
      We would suggest that you drain your pool, thoroughly clean it out and then refill with fresh water, adding the appropriate chemicals. Before doing this we would recommend that you contact one of our local suppliers in your area using the ‘find a supplier’ link at the top right of our site.
      Thank you.


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