How Often Should You Change Pool Water? (For all pool sizes)

All good pool owners want to ensure their pool is safe and clean to swim in, yet do not want to waste water unnecessarily.

It can be hard to determine how often you should change the water in your pool, as all our pools are different, from water capacity size to our individual maintenance schedules.

As a whole, there is no definitive rule for when you should change pool water as it depends on pool maintenance and size. Typically, pool water needs to be replaced every 5 to 7 years for large, in-ground private pools, once a year for above-ground pools and daily for small inflatable kiddies pools.

Some of us have small above-ground backyard pools, while others have large in-ground pools with a very large capacity and there is not one rule to suit all.

It is possible to never drain your in-ground pool and most experts agree you should not drain your in-ground pool unless you absolutely have to. Most water problems can be treated using chemical balancing.

If you must drain your in-ground pool, it is essential to consult a pool professional before draining, as the change in water weight can cause serious structural damage, depending on the type of pool. [source]

In this article, I will cover how often we should change our pool water, considering the pool size, covering:

  • How often should you change pool water?
  • How often should I change the water in an above-ground pool?
  • How often do public pools change their water?
  • How often should I change paddling pool water?
  • Should I drain my pool and start over?

How Often Should You Change Pool Water?

As a responsible pool owner, this is such a challenge to work out. I don’t want to waste water, yet I want to ensure that anyone who uses my pool is safe.

If you have a large in-ground pool, changing pool water is an enormous task and one you will want to avoid.

From my personal experience, I have found that nearly all pool maintenance experts will give you a different answer to how often you should change pool water.

For large in-ground pools, some experts argue it is possible to never change the water if you keep your pool well maintained. Others recommend changing your pool water every 5 to 7 years for in-ground pools.

Based on my own extensive research, I have compiled the following table on how often you should change pool water based on the type of pool you have.

Type Of PoolHow Often Pool Water Should Be Changed
In-Ground Private PoolOnce every 5-7 years
Above Ground Pool1 time per year
Above Ground Small PoolEvery 10 Weeks
Public Pool1 time per year depending on the country’s regulation
(Most public pools will never drain if possible)
Paddling Pool (Kids Size)Daily
This Table Shows How Often Pool Water Should Be Changed

In-Ground Private Pool – How Often Should You Change Pool Water?

The sizes of in-ground private pools vary dramatically and how often you should change your pool water depends on the following factors:

  • The water quality.
  • How often you clean the pool.
  • The chemical balance of the pool.

As a general rule, most experts agree that the water should be changed in a private in-ground pool every 5 to 7 years.

It is possible to get your water looking fantastic without completely draining your pool. It is generally not recommended to drain your pool. You must take great care if you ever drain the water, as the pool wall could collapse or an in-ground pool “pop out” due to ground forces.

If you are a private pool owner and concerned about your pool, it is best to hire a pool maintenance company to care for your pool, or if you are feeling up to it, take the DIY approach by learning from experts such as Swim University.

Swim University is an amazing resource for any pool or spa owner, from large in-ground pools to easy-to-set-up above-ground pools.

I followed their advice when setting up my pool and it feels so good to have the knowledge and confidence to manage your own pool.

They have a wonderful pool care handbook and video course so you can become an expert at managing your pool.

How Often Should I Change The Water In An Above Ground Pool?

Above-ground pools, including Intex pools, steel-frame and inflatables, need the same level of care and attention as an in-ground pool, however, they are often much smaller.

As a result, they can be much easier to maintain and clean.

Typically, above-ground pools should have the water changed once per year.

Personally, I like to empty my above-ground pool at the end of the swimming season, which is late October for me and re-open my pool in late April as it is a very small above-ground pool.

I take great care of my pool, checking the water 2-3 times per week using water test strips. In addition, I skim my pool every day with a pool skimmer, while running the filter for a couple of hours.

I will empty my pool and clean it completely before storing it away for the winter.

For larger above-ground pools, it is not always practical or necessary to change the water once a year and it is possible to empty your pool less frequently than this, especially if you take great care to maintain crystal clean water.

If you are going to close your pool for the winter and plan to not empty it, I recommend you learn how to winterise your pool.

It can cost a few hundred dollars to do this if you hire a pool maintenance company, but it is possible to learn how to do this yourself.

I recommend Swim University again to learn how to do this. They have a wonderful course that can teach anyone how to protect their pool in the winter, be it an in-ground pool, above-ground or Intex pool.

Above Ground Small Pool – How Often Should You Change Pool Water?

Small above-ground pools are very popular and are a great option for those who have a small garden.

I consider anything smaller than 3m x 3m as a small above-ground pool.

I am a big fan of the smaller pools and have swum in a small pool in my garden. I have covered how you can do this using a swimming harness in this article, Can You Swim In A Garden Pool? (A full setup guide)

I typically change my pool water every 10-12 weeks in my small above-ground backyard pool. As the volume of water is not large, I feel it is not wasteful to do this as I use the water every day.

I clean the water every day with a pool net, to remove larger debris and then run the filter. I also use test strips to monitor the quality of the water.

I usually winterise my pool for the winter months, therefore, I can typically go from April to October with just one water change. If I had a better rain cover, I am sure I could go the full season without a water change if I maintain the water quality daily.

How Often Do Public Pools Change Water?

Public pools typically change pool water once a year, but this will depend on where you are in the world.

For example, in France, it is mandatory to drain public pools once per year. This was twice per year previously, but a change to regulation in 2017 has changed this to once per year. [source]

Most public pools in the UK will avoid draining pools if possible.

It is a major operation to empty a public pool, especially as most public pools are 25 meters. It can take a few days to refill based on pool size and water flow rate.

In the UK, there are no pool-specific health and safety laws, so public pool management is covered under the Health and Safety at Work Act 1974. [source]

I contacted my local pool, which runs an excellent and exceptionally clean 25-meter pool, to ask how often they change or drain their pool water, if at all.

Here is the reply they sent to me:

We never drain the pools, however we backwash (clean the sand filters) once a week and when we do this there is a flushing out process which means dirty water and debris goes to the drains and we fill up the system with fresh water. We are constantly monitoring the chemical levels in the pools and an automatic dosing system injects the relevant chemicals into the pools as and when necessary.

UK Public Pool

My local pool is very clean and fresh and in the 10 years I have been swimming there I have never suffered any illness or skin rashes as a result of that pool.

It is a major task to empty a big pool, and this example shows it is unnecessary to drain a pool to maintain excellent water quality.

How Often Should I Change Paddling Pool Water?

For smaller kids paddling pools, change the water daily.

You should think of your small paddling pool like a bath. It will not have a water treatment system or filtration system. As a result, water will just sit there and the water quality will deteriorate with time.

If just one child is using the pool, and the pool is carefully covered and cleaned, then it may be acceptable to change the water once every 2-3 days.

However, if the pool water is shared amongst many children, it is best to change the water daily to prevent bacteria and virus infection. [source]

When changing the pool water in a paddling pool, it is important to clean the pool itself by wiping down pool wall surfaces using an anti-bacterial spray. This will ensure that all the pool surfaces are kept clean.

Should I Drain My Pool And Start Over?

Many experts agree that draining your pool and starting over, especially if it is an in-ground pool, is the last resort. [source]

There is a real possibility of damaging your in-ground pool if you drain it. It is always recommended to consult a pool professional before draining your pool.

Some pools, like liner pools, must never be drained, while concrete and fibreglass pools may require hydraulic balancing to be drained safely without causing structural damage. [source]

A time will come, however, when you will need to drain your pool. A pool might need to be drained for maintenance work, repair, painting or to change the water when TDS levels get too high.

Pool chemicals can do a lot of work to save you the need to change pool water, however, eventually, the total dissolved solids (TDS) will reach a point where filtration will not work. Correct pool chemistry will be hard to maintain at this point.

As a general rule, once TDS levels reach 2500 parts per million approximately, draining the pool and replacing the water with a fresh clean supply is the best course of action.

If you decide to drain your in-ground pool, ensure you have done everything you can chemically to fix any problems before taking this route.

Excellent online resources such as Swim University can help you understand your pool chemistry and give excellent and professional advice on when to drain your pool.

Final Thoughts

Whether you’re a public pool manager or the owner of a smaller paddling pool, knowing how often to change pool water is essential for keeping swimmers safe and healthy.

While there are no hard and fast rules, the consensus is that public pools should be emptied and refilled once per year, while smaller untreated paddling pools should have their water changed daily.

Typical in-ground private pools should have their water changed every 5 to 7 years.

Of course, if you have any concerns about your pool water quality, it’s always best to consult a pool professional who can help you fix any existing water chemistry problems or help you plan to change your pool water without structurally damaging your pool.

Happy swimming!

Emma Moore

Hi, I am Emma, and I am obsessed with all watersports, from swimming to surfing and everything in between. I spend my free time in the water or preparing for my next water travel adventure.

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