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How Often Should You Change Hot Tub Water? – Complete Guide

How often should you change hot tub water is a question many new owners want to know the answer to and over the years on our journey to becoming the UK’s leading spa guide, we’ve discovered there is no definite. 

It depends on several factors such as the size of your model, how often you use your spa and your water chemistry levels. If you’re having trouble getting your PH levels balanced, chances are there’s a water-quality issue. 

Some fancy hard-shelled tubs run continuously and have filtration systems that can keep the water clean for up to a year. However, hot tub experts BISHTA (British and Irish Spa and Hot Tubs Association) advise changing the water at least every 1-3 months to maintain water quality and for health and safety reasons. 

How Often Should You Change Hot Tub Water in the UK

You should change the water in an inflatable hot tub at least every three months. We get asked the question how often should I empty my hot tub regularly on this site. We think 3 months is the maximum you should leave a hot tub water change.

Here’s a guide to draining your Jacuzzi, but in this post, we’ll take a look at something even more critical. – What signs mean you need to change the hot tub water and what will happen if it isn’t changed on a regular basis. 

The good news is that it’s relatively simple for hot tub owners to empty and refill their garden spa, so changing the water should be hassle-free 

Why You Need To Change Hot Tub Water

It can come as a surprise to hot tub owners that the water needs to be changed so much. After all, don’t the chemicals keep the hot tub clean and free from bacteria? 

Well, yes, they do; however, after a while, the hot tub water becomes saturated, especially with a heavy bather load; basically, this means that no more solids can be dissolved and bacteria will start to build. 

The only solution is to empty your hot tub and refill it with fresh water.

Signs I Should Change My Inflatable Hot Tub Water

a plaster in a hot tub

Your water is cloudy, greasy or slimy?

Cloudy hot tub water is a sign of a problem. Whether caused by oils, shampoo and fake tan, not performing regular maintenance or low-quality chemicals, murky-looking water is always an indication that your hot tub water needs to be changed. 

If you notice that your hot tub water is cloudy and slimy, then it might be worth checking out why and what you can do to resolve the issue.

To remove foam build-up.

Foamy water indicates your water quality is not what it should be; like cloudy water, it can be caused by a build-up of body oils, beauty products, and fake tan after heavy usage and if there is a chemical imbalance. 

You can try scooping the foam out or using a de-foaming product, but these are just temporary solutions; they won’t actually fix the problem. You could try shocking your tub with Chlorine, but the best way to get rid of hot tub foam once and for all is to drain your hot tub and refill it with fresh water.

The water is whiffy

Smelly water in hot tubs is unpleasant and can also be detrimental to your health as it signifies something more serious amiss. 

Your PH level may be too high, your hot tub filters may be clogged, or your sanitiser isn’t working well enough to eliminate harmful bacteria. Whatever the reason, when you notice a nasty pong, it’s time to change your hot tub water

You suspect someone has peed in the tub.

Some owners don’t realise the dangers of a child or adult peeing in the tub. When the urea combines with Chlorine, it produces a toxic gas called Chloramine which can cause respiratory issues, sore throats and skin irritation. 

Hence shocking with even more Chlorine after someone has peed in the pool won’t help. You should change and replace it with fresh water before you use your hot tub again. 

You live in a hard water area.

scale build up in two filters causing blockages

Hard water is a big problem for inflatable hot tubs. It contains an overabundance of minerals such as calcium and magnesium, leading to scale build-up in the filtration system and other components. 

You can use a hard-water treatment, but if you live in a hard water area of the UK, you will need to drain and change your hot tub water more often than in soft water areas. 

Using cheap chemicals

You may think you are saving money by buying cheaper chemicals for your hot tub water. However, we’ve found that in the long run, it’s better to go with good quality products like Clearwater chemicals to avoid issues and spending more by having to change hot tub water more often. 

If you are unsure about what chemicals to use, see our hot tub chemicals guide and find the right solution for your water.

Heavy usage

Most of the organic matter in a hot tub comes from bathers, dead skin, body oils, beauty products and make-up, so it stands to reason the more you use hot tubs or a spa, the more the water will need to be changed to keep your hot tub clean and safe for use. You’ll be surprised at what a comfortable soak you’ll have with fresh water without worrying about bacteria lurking. 

Dirty or clogged filters

If your filters are not fitted correctly or are dirty, they won’t be doing their job and you will need to change the water in your tub more often. Always ensure you rinse your filters after each use and change them regularly for a much more comfortable soak.

You see how to clean hot tub filters with dishwasher detergent or vinegar here.

Leaving Water in a Hot Tub Untreated

an image saying hot tub rash between two hands

Bathing in the dirty hot tub water doesn’t sound very appealing and it’s not great for your hot tub either. Without regular water maintenance, scale may cause damage to the components and the cost to run will increase as your spa pump works harder.

TDS (total dissolved solids) build-up

Whenever you enjoy a relaxing spa experience, you leave a long list of contaminants in the water, sweat, perfume, urea, deodorant, dead skin, and make-up, to name but a few and these are referred to collectively as total dissolved solids or TDS.

Your sanitiser will typically treat the dirty water, but it will become ineffective if you don’t replace the water often enough. This is because the large amount of TDS will stop it from mixing with the water. 

Your water will become cloudy and may start to give off an unpleasant odour or feel gritty. Basically, you will be sitting in a soup of gunk. 


Remember those science experiments at school when you added teaspoons of sugar or salt to a tumbler of water until it stopped dissolving to find the saturation point. Basically, it’s the same in your spa; you’d start seeing scale build-up on your fixture’s residue of calcium which isn’t dissolved by the water. 

Water can only hold a certain amount of other stuff before becoming oversaturated, so it’s essential to replace it regularly. Not only to keep it perfectly clean but to prevent damage to your new hot tub and increase its longevity.

Can You Get A Hot Tub Clean Without Draining It?

Yes, you can clean the water in a spa without draining it; simply wipe away any marks on the liner of the tub, and take care when wiping the bottom base and the surface. 

Remove the filters from the filter housing and give them a deep clean.

As a general rule administering a Chlorine shock treatment should get your water’s chemistry levels back to normal and destroy any bacteria. Still, you will need to add new water eventually. This is the right guide for general inflatable hot tub cleaning.

Do Smaller Hot Tubs Need Changing More Often?

a couple sat in a hot tub smiling

Because there is less water in small hot tubs, the hot tub can become saturated quicker, meaning if you own a 2-4 person hot tub like the Miami, the water will need to be changed more frequently. This equation below can be used to estimate when to change.

Divide the number of gallons your new hot tub holds (you can find this in the owner’s manual or on the website) by three. The resulting figure then needs to be divided by bather load, i.e., the number of people that use the hot tub daily. 

How Often Should You Change The Water In A Lay-Z-Spa

Lay-Z-Spa’s advice is in line with BISHTA’s saying on their website that you should drain and change the spa’s water between 1-3 months. 

They also go on to mention that the more people who use the tub and insufficient water care will affect this. They also recommend administering regular Chlorine shocks as this will decrease the frequency of your spa needing to be drained. Here is a guide on shocking a Lay Z Spa hot tub.

What Do Other Big Brands Say 


This brand really shines when it comes to filtration with some unique features not found elsewhere on a hot tub; however, the water will still need to be changed regularly. MSpa also advises that this depends on how many people use the tub and how often. 


Intex doesn’t give exact time frames to give their units a good clean but explains, as mentioned above, that heavy use and chemical imbalances determine when you need to drain and refill the tub.


We didn’t find much information on water care on the official website and nothing on when your spa needs drained and refilled but imagine it would be in line with others every 4-12 weeks depending on usage. 

Wave Spa 

Once again, we didn’t find the answer to how often should you change spa water on the Wave Spa website. 


Jacuzzi provide a simple equation similar to the one we’ve used above to determine when it’s time to change the spa water. 

Key Takeaways 

We recommend changing your hot tub water every 1-3 months, depending on your ability to retain the water chemistry and if you use the hot tub every day or just once a week. Consider doing a daily maintenance checklist for your hot tub and this will help you remember key things to check for or do when inspecting your spa.

You don’t want to overdo it either; emptying hundreds of gallons of hot water every week will literally see your money going down the drain. 

Shock treatment can temporarily improve the water in an inflatable hot tub, but unfortunately, whatever sanitiser you use won’t keep the hot tub water clean forever. 

Maintaining the delicate balance of your hot tubs water, using a cover, and showering prior to using your hot tub will ensure it stays clean for an extended period; however, this will vary based on bather load and often the hot tub is used.


Can I do partial water changes?

How often to change hot tub water if not used

When to change the water in a salt water hot tub

Last Word 

a hot being filled with a hose

Water changes are essential for a hot tub as they prevent bathers from bacterial infections and keep your hot tub operating at its best. 

So in answer to the question “how often to change hot tub water?” there is no definitive answer; for example, it depends on a lot of things including how often and how many people use the hot tub and even clean water can need changing if the chemicals are out of whack. 

A good rule of thumb is to change hot tub spa water every 1-3 months. If you notice a funny smell, have been neglecting your water care, or a Chlorine shock hasn’t worked to restore balance, you should drain and refill your hot tub. 

John Devlin

Hello, Welcome to my website. I’m John, and I created the InflatableHotTubGuide while researching these spas nearly a decade ago. Since its creation, the site has become the leading UK resource for many models. As a passionate hot tub user, I love to test and explore all the latest machines this industry keeps creating. I hope you find our content helpful.