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How Often Should You Change Your Hot Tub Water?

How Often Should You Change Hot Tub Water
Written by Elizabeth Fincher
Last Update: August 10, 2023

You should change your hot tub water once every quarter. There is also a formula that you can apply to figure out how often you should change the water of your regular/inflatable hot tub and spa.

You can either follow the general rule of thumb or can figure out the frequency from the formula. Here will talk about all you need to know about changing your hot tub water.

How Often Should You Change Your Hot Tub Water?

On average, you need to change the water in your hot tub once every 3 months.

How frequently you need to change your hot tub water will depend on the water quality and how often you use the tub.

Once you soak your body into your hot tub water, the water collects all kinds of debris from your body. There is environmental debris like fungi or algae buildup or external pollutants that can change the water quality as well.

How Often Should You Change Your Hot Tub Water

In case you use your hot water quite frequently, you may need to change the water before reaching the 3-month timeframe. On the other hand, using your hot tub less frequently will make your hot tub water to be in good shape for longer than 3 months.

The Best Way to Clean Your Inflatable Hot Tub – Quick and Easy

You’ll need a bit of calculation to figure out this one. Inflatable hot tubs don’t work like regular hot tubs due to the lack of water jets. Plus, they are usually smaller and can hold less amount of water.

The Formula

The process goes like this: You need to find out how much water your inflatable hot tub can carry. You can find this information in your user manual. Suppose, your inflatable hot tub can hold 210 gallons of water. Now, you need to divide the amount by 3.

You’ll get 70 as a result. After that, find out how many people use the inflatable hot tub regularly and divide the result you’ve got from the previous calculation with the number of people who use the tub.

Suppose, 3 people use the tub regularly. Now take the result from the previous calculation (70) and divide it by the number of regular users (3). The result you’ll get will be the number of days after which you’ll need to change the water in your inflatable hot tub.

The formula goes something like this:

The frequency (In days) = (Water holding capacity of the tub ? 3) ? Number of tub users

In our example, the final result is 23.3, and that indicates you’ll need to change your inflatable hot tub water every 20-23 days.

The Truth About the Benefits of a Spa Day

For your spa, you can either follow the general rule of thumb to change the water once every 3 to 4 months or you can use calculations to determine the suitable frequency for finding out the optimum duration for changing your spa water.

The calculation isn’t a hard and fast rule though. You can change the water before the intended time if you feel like it. However, we recommend you don’t use the water that is sitting in your pool for over 4 months.

In a nutshell, you can change the water before 3 months but it’s not advised to prolong the period for more than 4 months.

What Controls the Frequency


The water in your hot tub will get dirtier with every use. Remember, the heat increases the solving power of water, and the hot water tries to dissolve every debris that comes in its contact.

These debris include dead skin cells, body oil, perfume, dandruff (in case you dive in), and other skin products. Sometimes people spill drinks into the water as well. All these items change the water quality for the worse and eventually, the water becomes too contaminated to use.

Water quality

The initial water quality will also affect how long you can use it without changing. For example, if you use “Hard” water, you may need to change your hot tub water more frequently.

Hot tub Water quality

Hard water is rich in minerals like magnesium and calcium, which can not only affect your water quality by making them saturated faster but can also affect the internal parts of your hot tub over time.

Using “soft water” or balancing the water with chemicals can help you with this problem.

The chemicals used

Using higher-quality chemicals at the right time can make your hot tub water fresh for longer. Utilizing chemicals is essential to keep the water in your hot tub in its peak condition. To ensure this, you need to go through your user manual and stick to the guideline mentioned there.

Failing to maintain your hot tub regularly can make the water unusable quicker than you think. Additionally, using high-quality chemicals also helps to keep your hot tub water fresh.

Cheap chemicals won’t dissolve in the water well, leaving residue and deposits behind that can make the saturation process faster. You’ll also need to use a lot more chemicals, which will contribute to polluting the water.

The filtration system

To put it bluntly, the better your filtration system is, the longer your hot tub water will remain fresh. Some of the high-end hot tubs provide a state-of-the-art filtration system and as a result, they don’t need a change of water in a year!

The job of your filtration system is to remove all the contaminants and debris from your water. That is why a good quality filtration system is essential if you don’t intend to change your hot tub water often.

Signs of a dirty hot tub


One of the most prominent signs of contaminated water in your hot tub is the water becoming cloudy or blurry. If spotted early, using chemicals like a sanitizer or clarifier can help you solve the issue.

Signs of a dirty hot tub - Cloudiness hot tub

However, you’ll need to change your hot tub water if the contamination spreads too much.

Harder maintenance

If you notice the regular maintenance of your hot tub becoming harder or requiring more chemicals than usual, it most probably is the time to change your hot tub water.


Seeing foams forming in your bathtub may be a pleasant experience, but it certainly isn’t a good sign to see foam or bubbles forming in your hot tub. You can try using foam removers, but if that fails, you’ll need to drain and refill all the water.

Signs of a dirty hot tub - Foamy Hot Tub

Weak water flow

Over time, the filtration system and the water circulation system may become weak due to clogging. You’ll notice this in for of weak water flow. The best course of action is to drain the hot tub, clean/replace the system, and fill the hot tub with fresh water.

Unpleasant odors

Unpleasant odors in hot tub

This is another dead giveaway that you need your hot tub water changed ASAP. This might be true that chemicals can help a little bit here, but the best option is to change all the water in your hot tub to avoid unpleasant circumstances.

How to Change Your Hot Tub Water?

Here’s an in-depth guide on how you can change your hot tub water easily:

What happens if you don’t change the hot tub water

The water will become oversaturated with time from collecting all the chemicals and bio-contaminants. If the contamination reaches the limit, no matter how much chemical you put in your hot tub water, it won’t be enough.

The human wastes like sweat, perfume, lotion, shampoo, makeup, deodorant, body oils, and other bodily fluids are commonly known as Total Dissolved Solids (TDS). Not only can they spoil the appearance and the smell of your hot tub water, but they can harbor a number of germs.

What happens if you don’t change the hot tub water

As a result, the water of your hot tub will turn into an unhygienic, smelly, and disgusting goop. That’s why regular maintenance of your hot tub water is essential.


1. How long should I run the filter on a hot tub?

Ans: It’s a good practice to run the filters twice a day. The length of each filtration cycle will depend on how many people use the hot tub. If 2 people use the tub, it is recommended for each cycle to last 2-4 hrs. In case of 4 people, the filters should run for at least 8 hrs.

2. Can I run a hot tub without a filter?

Ans: You shouldn’t. Running a hot tub without proper filtration will not only make the water unhygienic, but it can also damage the inner parts of your hot tub that can cost you a fortune to repair.

3. What’s a self-cleaning hot tub?

Ans: Self-cleaning hot tubs offer advanced filtration systems that run constantly and reduce the amount of maintenance needed to an extent. However, all hot tubs will require some level of outside maintenance every once in a while.

About the author

Elizabeth Fincher

Elizabeth started her career as an interior design artist at a multinational interior design farm. She completed her masters degree from the University of North Texas back in 2010. She was also a Spelling Bee runner-up when she was 14. She took interest in bathroom interior designing after joining her first job. Later she started her own firm as an independent artist. She’s been one of the founding members of Toiletsguide. She examines the design and ergonomics of the units we review and directs the interior decoration team of our in-house research facility. Elizabeth plays piano masterfully and always finds time to entertain us in between our busy schedules.

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