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How Often Should You Drain and Refill Your Hot Tub?




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If you don’t own a hot tub, you might not be aware that you have to clean them regularly.

It is a common misconception that, just like swimming pools, all you need to do is add a ton of chlorine to it and the water will clean itself. But this simply isn’t the case.

While adding chlorine to the water will help clean it somewhat, the amount of dirt that your hot tub will gather from both you and the outside environment that you keep it in is way too much for some chlorine to handle.

But if you didn’t know that you have to clean your hot tub, there’s an even bigger chance that you don’t know how often you have to clean it. This differs depending on a lot of different factors which we will take a look at in this guide, but generally, you should aim to clean your hot tub every couple of months.

Let’s take a deeper look at why.

How often should you drain and refill your hot tub?

As we have stated, you should aim to drain and refill your hot tub with fresh water every couple of months. This is a very general number, and if you want to be more specific you should aim to empty your hot tub every 3-4 months.

If you want to schedule emptying and refilling your hot tub into the calendar then you should enter it quarterly to keep on top of the maintenance.

But remember that this is just a general guide, and as we said earlier, there are some other factors that will impact how often you should drain and refill your hot tub.

Some of these things are obvious, for example, if your hot tub gets mud in it, you should clean it before the 3 months is up, but some are a little less clear. Let’s take a look at what they are.

One thing that will impact how often you should drain and refill your hot tub is the size of the hot tub and the volume of water that it holds.

You can use the volume of your hot tub to calculate the specific amount of times you should empty and refill your hot tub in a year, and we’ll take a look at this calculation shortly.

Another thing that will impact whether you should clean your hot tub more regularly is how often you use it. If you only use your hot tub on the weekends then the water will be fine for the full 3 months.

But if you use your hot tub almost every day then the water will become dirty a lot quicker, and so you should clean it more regularly.

Now let’s take a look at how you can calculate how often you need to empty and refill your hot tub.

Calculating how often you should change your hot tub

While you should aim to change the water in your hot tub once every 3-4 months, you can calculate a more specific time frame of how often you should do this.

The formula for this calculation is very simple, and it is a great way to get a specific schedule of maintenance for your hot tub.

To be able to calculate how often you should change your hot tub water you will need 2 key pieces of data, they are:

  • Hot Tub Volume
  • Bather Load

The hot tub volume is self-explanatory, and all you need for this is the specific volume of water that your hot tub is able to hold at one time.

This is important as smaller hot tubs will require changing more regularly than hot water.

If you don’t know the exact amount, here’s a quick average:

  • 2 person hot tub = 170 gallons
  • 4 person hot tub = 330 gallons
  • 6-8 person hot tub = 475-510 gallons

But, for your specific hot tubs amount, you should check your user manual.

Calculating bather load is a lot easier, as all you need for this is to work out the average number of people who use your hot tub at any one time. This doesn’t be specific, so it should be easy to work out.

Once you have this number, you can then substitute them into the formula:

Hot Tub Volume *divided* 3 *divided* Estimated Average Bather Load

So if you have a 330 gallon hot tub, and your average number of bathers is 4 then you should change the hot tub water every 28 days.

Of course, this is just a guideline, so there’s no need to worry if you are unable to change the water in your hot tub as often as this statistic suggests.

What happens if you don’t change it?

In the back of the mind while you’ve been reading this you might be asking yourself one question and that is ‘what happens if you don’t change your hot tub water?’.

If you are someone who hasn’t changed their hot tub water in a while the answer might make you apprehensive, but there’s no need to worry.

The main thing that happens if you don’t change the water is that it will become dirtier and dirtier. Without even considering the dirt that could enter the hot tub, the water in the hot tub will change form the longer that it goes unchanged.

In this process, the water will go hard, and if left unchanged for an excessive amount of time this can begin to form a scale on the key components of your hot tub which can cause irreversible damage if the water is not regularly changed.

Additionally, every time that you use the hot tub contaminants will fall off of your body into the water, including things such as deodorant, perfume, lotion, and lots more.

So while the main thing you have to worry about is dirt, it is important to clean your hot tub regularly to avoid it becoming damaged beyond repair.


In short, you should clean your hot tub at least once every 3-4 months, but if you want you can calculate a more specific time scale using the formula we looked at above.

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