How Often Should I Empty My Hot Tub? (Let’s Find Out!)

By James Brockbank •  Updated: 12/29/21 •  12 min read

How often should I empty my hot tub?

You should empty your hot tub every 3 to 4 months, depending on usage. If the water becomes too dirty or can’t achieve chemical balance, draining the hot tub becomes necessary.

Stop wasting time and money with hot tub maintenance and confusing water chemistry! The Hot Tub Handbook and Video Course will help keep your hot tub balanced, sanitized, and crystal clear all the time.

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My recommended product to help you test your spa water for accurate pH, alkalinity, bromine, and chlorine readings is the AquaCheck Trutest Digital Reader.

Hot tubs are usually ready to use any time you want because the water is always hot. But this does not mean that it always has the same water quality. 

This is why every hot tub owner wonders how often I should empty my hot tub?

Many foreign materials enter your hot tub and result in the buildup of microorganisms and bacteria. 

In addition, the high hot tub temperatures and the fact that multiple people enter and leave the hot tub creates a perfect environment for bacterial buildup. 

As a result, you will need to change the water from time to time for your safety and the wellbeing of your hot tub. 

How Often Should I Empty My Hot Tub?

On average, experts recommend emptying your hot tub every 3 to 4 months. Draining allows you to start with fresh water in your hot tub with a stable chemical balance.

You might find different and confusing information out there giving you different durations to empty your hot tub. While you can change the hot tub water any time, you realize degradation issues with the water happen over time. 

Specifically, suppose the water starts to be cloudy, releases bad odor, and other issues that regular maintenance cannot eliminate. In that case, you may need to empty the water to clean and fill the system with fresh water. 

Ensure that you are testing your water regularly to maintain a good chemical balance because failure to do so might force you to change the water in a shorter interval than mentioned. 

Empty your hot tub if you’re not using it in the winter. 

Don’t leave the system running if you’ll be spending your summer away from home because it will consume a lot of power, and nobody will be around to use it.

How To Empty a Hot Tub

There are two methods on how to drain a hot tub. The first is to use a submersible pump to suck the water out of the spa. A 1/4 horsepower utility pump should do the trick. The second is to attach a hose to the drainage valve and let gravity do the work. It can take up to 2 hours to drain a hot tub. However, this depends on the size of the spa and the amount of water it holds.

I recommend the Superior 1/4 HP Thermoplastic Utility Pump.

How To Tell If Your Hot Tub Water Needs Changing

If your hot tub is foamy, cloudy, has a bad chemical smell, and hasn’t been drained for quite some time (longer than 4 months), it may be time to drain it.

Foamy and Cloudy Water

If you open your hot tub cover and realize that it is foamy or cloudy, you may try to clear it up with a spa shock. However, you may also find a bunch of foam while soaking in the hot tub

A foam remover can help eliminate the bubbles. However, it does not always work. 

It works for a little while because you’ll be treating the symptoms and not the root cause for the problem. 

The solution to the issues is draining the hot tub to remove any problem associated with the foaming and clouding. 

Bad Chemical Smell

The last thing you want while soaking is a bad smell, especially because you intend to relax your body and calm your mind. 

Experts assert that a foul smell is one of the clearest signs that it is time to change your hot tub water. Water is odorless, so there should never be any scent coming from your hot tub. 

If your hot tub water is stinking, it could be harboring biofilm in the plumbing fixtures, mildew, and possibly bacteria. 

In any of these cases, no amount of shock will help to eliminate the smell, which is why it must be changed with fresh water. 

Check When You Last Drained The Water

For hot tub owners, the volume, the number of users, the frequency of use, the water quality, the location of the hot tub, and the quality of care and maintenance determine the exact duration you will take to change your hot tub water. 

Many factors determine the duration of changing the hot tub water. If you have been using a hot tub for some time, you possibly know the duration it takes to empty your hot tub. 

If you’re new to the hot tub, the general formula for determining when to change your hot tub water is dividing the volume by three and dividing the answer again by the average bather load. 

In so doing, you’d realize that smaller hot tubs require more frequent emptying than the larger ones. However, they will usually average to around 3 and 4 months. 

Therefore, you may want to check the last time you emptied your hot tub to determine whether it is time to do this again. 

bromine tablets for hot tubs

What Happens if I Don’t Change the Hot Tub Water?

The number of total dissolved solids will rise to the point where sanitizer and filtration will not be able to remove it effectively. Supersaturation of spa chemicals will also occur if no freshwater has been added over a long time. This includes calcium buildup, which leads to scaling.

You may only reconsider not changing your hot tub water if you don’t know what you will be getting yourself into. 

Total Dissolved Solids

The total dissolved solids refer to everything mixed in hot tub water. Some of these matters are added deliberately, while others passively find their way into the hot tub. 

The chemicals that we rely upon in maintaining the water are part of the total dissolved solids, meaning that we cannot rely on them entirely to keep the water clean.

After the recommended duration, failure to drain the hot tub will accumulate the total dissolved solids. These matters will make the water uncomfortable to bath because it will look murky, produce a bad odor and feel gritty.  

The pH minus, pH plus, the bromine and chlorine that we add into the water to keep it clean leaves many residues behind that adds to the total dissolved solids. 

The additional components further elevate the total dissolved solids in the sanitizers like cyanuric acid, preventing the chlorine breakdown in sunlight. 

Foreign matters that dissolve in water include shampoo, body lotion, fake skin or tan, dead skin, perfumes, and dry leaves or dust.

The sanitizers will handle any harmful substances while the larger matters will be trapped at the filters. Nevertheless, the majority are left to contribute to the total dissolved solids. 


Failure to change the hot tub water will lead to supersaturation. Water can hold other substances but only to a specific limit. For example, substances like calcium are usually resent in your hot tub in the form of dissolved salts, called calcium chloride, that causes the water’s hardness. 

If you never change the hot tub water or wait too long to change it, these salts will stop dissolving. 

The accumulation of salts and other substances that are supposed to dissolve in the water will start scaling the hot tub fixtures, pumps, and filters. 

Excessive scaling might damage the hot tub equipment and possibly cost you a lot of money. 

How Often to Change Hot Tub Water Calculation?

The use of numbers increases the accuracy of predicting the required time to change their hot tub water. The key determining factors on the exact frequency for changing the hot tub water include the volume, usage load, which are usually applied to the water change formula to determine the interval. 


Hot tub volume indicates the water capacity. The typical volumes of the various hot tubs are as follows: 

You can also find your manufacturer’s manual values for more accurate model results. 

Usage Load

Usage load is the number of users and the frequency of usage. Although you may not get the exact number every day throughout the year, you’ll need to estimate this value to help you find the correct water change frequency. 

Water Change Formula

After obtaining the figures in the first two steps above, divide the hot tub volume by three. Then divide your answer with the bather load as shown in the formula below: 

Change Freq. = {(Hot tub volume ÷ 3)/estimated average bather load}

How Long Can a Hot Tub Go Untreated?

A hot tub can typically go untreated between 2 and 3 weeks before the water becomes unsafe to soak in. Untreated water typically means no sanitizer, pH balancer, or other added chemicals. Only tap water exists inside the spa.

You cannot neglect to treat a hot tub. A hot tub treatment should be a routine activity because failure or negligence will cause problems to the users and the hot tub itself. 

Experts recommend that you shock your hot tub every once a week. In addition, you should also balance the pH, alkalinity, and sanitizer by checking every week to ensure they are at the correct levels. 

If you fail to conduct these routine maintenance practices, you might experience bigger issues with your hot tub that require more effort to clean the entire system and drain all the water. 

Although there would be no exact time to leave your hot tub untreated, the best guideline should be the number of users and the frequency of use, the current water conditions, and the effectiveness of the chemical you are using. 

I recommend following your manufacturer’s guidelines for various treatment practices on your hot tub.


How Long Can a Hot Tub Sit Empty?

A hot tub can sit empty for several months without damaging any components. The only thing that matters is how well the draining was done and whether the system was properly dried. 

The hot tub should be properly covered if you’re going to leave it outside after emptying. But if you have emptied the hot tub for cleaning, it cannot stand for more than 12 hours, especially during the winter, because freezing can take place in the plumbing fixtures, filters, and other components.

Adding antifreeze to the hot tub in the wintertime is recommended.

Freezing of the water in these components might cause expansion and crack. 

How Do You Clean a Hot Tub Without Draining It?

The best way to clean a hot tub without draining it is to balance and sanitize the water, add fresh water, and clean the filters regularly. Check the hot tub chemistry and water quality regularly, and you should be fine.

Balance and Sanitize The Water

Regularly test the chemical balance in your water and make the necessary adjustments because failure to do so will affect the effectiveness of the sanitizers. For example, the pH should be in the range of 7.2 and 7.8, while the alkalinity levels should be maintained between 80 and 120 ppm levels. 

The importance of alkalinity is to ensure stability in the hot tub pH levels. The pH provides an appropriate environment for the chlorine or bromine to work. 

Sanitizers kill bacteria and other microorganisms in the hot tub water. Therefore, balance and sanitize your hot tub to eliminate the need for draining. 

Add Fresh Water

You can also choose to add fresh water if you notice unacceptable characteristics with your hot tub. For example, the old water might have degraded and cannot respond to the chemical treatment to remove the bad smell or cloudiness. 

If such a point reaches that the chemicals are not helping, try adding fresh water. You can remove old water and replace it with fresh without completely draining the hot tub. The freshwater will neither be oversaturated nor contain much of the dissolved solids. 

Clean The Filters

You can clean the filters as a measure for cleaning the hot tub without draining it. You can use different approaches to cleaning your hot tub filters after removing them from the hot tub. First, soak the filters with chlorine or bromine to kill any bacteria. 

You can also use vinegar for the same purpose. After you’re done, use a soft cloth to scrub the filters gently. Then, rinse it thoroughly with running water before returning them to the position. 

Dirty filters can harbor bacteria and microorganisms; thus, cleaning will go a long way in keeping the hot tub clean without draining it. 

I recommend Leisure Time O Filter Cleaner to soak your hot tub filters for the best results.

I recommend the Aquatix Pro Cleaner to get the job done right.

How Often Should I Empty My Hot Tub: Conclusion

how often should I empty my hot tub

From this article, you can tell that the average duration it would take you to drain your hot tub is between 3 and 4 months. 

The water volume and the frequency of use can shorten or increase this duration. But other signs can indicate that it is time to change your hot tub water like cloudiness and unending foaming, bad odors, murkiness, and discoloration of the hot tub. 

Your hot tub can stay for several months empty if you drain it properly and cover it.

I hope this article on how often you should drain your hot tub was helpful.

Thanks for visiting

James Brockbank

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