Hot tubs need chlorine to function safely, but what level is safe and when do chlorine levels become too high? Here is a guide with everything you need to know to dip and relax safely in your hot tub. 

You need chlorine in your hot tub in order for it to be safe. Chlorine will sanitise the water in your hot tub, and helps to kill bacteria and germs that could otherwise be harmful. 

How much chlorine should I have in my hot tub?

Chlorine is an essential part of hot tub maintenance, and you should have between 3ppm and 4ppm of chlorine in your water. The abbreviation ppm stands for parts per million, and it works out at around 1.5 teaspoons of chlorine per 1,000 litres of water.

If your chlorine is above 5ppm, this could be where it starts to get problematic.

Chlorine levelChlorine levels
To low0 – 2 ppm 
Ideal range3 – 4 ppm
To high 5 ppm
Dangerous6 ppm

How do you know if your chlorine levels are too high?

There are a few ways to tell whether your chlorine levels are too high in your hot tub, 

Water testing 

You should be testing your water a couple of times a week, anyway, either using the chlorine strips or a digital reader, to determine the chlorine levels of your hot tub. This is a great and accurate indicator of the chlorine levels, and you can even keep a log of them if you want to stay on top of it.

hot tub water testing


High chlorine levels can also irritate the skin. While this in itself is not harmful if you spot it and rectify it, it can be uncomfortable and those with skin conditions may be more affected. 


Either in your swimming costumes, trunks, or even in the hot tub cover if it is made of material, if you notice a discoloration or draining of the colour, this can also be a sign that your chlorine levels are too high.

What causes high levels of chlorine?

The main thing that causes high levels of chlorine is human error, in putting too much chlorine into the water. This can be either after cleaning and refilling, or perhaps chlorine had already been added by someone else using the hot tub. 

High levels of chlorine are able to be fixed, so don’t worry and we will give you everything you need to know about maintaining a healthy chlorine level in your hot tub.

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Is it safe to be in water with high chlorine levels?

High chlorine levels can irritate your skin, but in the short term, a slight increase in the chlorine in your hot tub water will not be dangerous. Prolonged exposure, however, can be dangerous and harmful to those using it, and you may notice symptoms such as nausea, vomiting, itchy eyes, and difficulty breathing. If any of these symptoms occur, you should seek medical attention. Dangerous levels of chlorine are 6ppm and above, this is when you need to stop using your hot tub and address the chlorine in your hot tub.

How can you reduce the chlorine in your hot tub?

There are a variety of ways to reduce the levels of chlorine in your hot tub, all with varying degrees of effort and complexity, here is a run down of them for you so you can choose your route. 

Please note we cannot give timescales because this varies based on your hot tub size, chlorine levels and other factors.

Give it time 

The easiest way to reduce your chlorine levels is to give it time. The chlorine levels will naturally reduce in your hot tub and if they’re not alarmingly high, will require little to no intervention. You will need to leave your hot tub for a few days but, if you don’t add any more chemicals, the levels of chlorine will naturally drop, and you can check in with either your chlorine sticks or with your digital testing device. 

You can let some of the water evaporate if you’re keen to hurry the process along, and leave the cover off to facilitate this happening. 

Letting the sun shine on your hot tub will also speed up the process; with the direct sunlight, you can expect your chlorine levels to reduce by about 2ppm in half an hour, but it is always best to check and retest your water, as timings will vary.

Turning on the jets of your hot tub during this process will also help things move in the right direction.

Drain your hot tub

There is an option to drain, clean, and refill your hot tub, but keep in mind that this is rarely necessary. Draining your whole tub can be a laborious task and wasteful on the water front, and you will rarely need to drain it in the case of high chlorine levels. 

However, we know that some people would rather have peace of mind from replacing all of the water, and giving the tub a thorough clean. Plus, if it is around the time you would be doing this anyway, it might make sense to kill the two birds with the one stone.

Replace part of the water 

Replacing a third of the water in your hot tub, for normal, non-chlorinated water is an option you can try too, in order to reduce your chlorine levels in the hot tub. 

This involves removing a third of the water from your tub, which again can be quite laborious, and time consuming, too. 

If you don’t have the time to let your hot tub stand and for the chlorine to reduce on its own, this is one of the more favourable options, and will take less time than replacing all of the water in your hot tub.

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Other methods

There are some alternative methods out there suggested by other websites, and even hot tub companies from overseas. These methods include Oxidiser, lemon juice and baking soda amongst others, but there is not enough evidence to suggest that these methods work, or are even safe. While there are lots of options out there, it’s always best to let your chlorine evaporate naturally.

Can high chlorine levels damage your hot tub?

High chlorine levels can cause damage to your hot tub over a long period of time, and can damage your hot tub cover, also. Maintaining an appropriate level of chlorine in your hot tub is best for those using it, and for the health of your hot tub. 

How can I maintain the chlorine levels in my hot tub?

Hot tub maintenance is an important part of ownership, and you can maintain the chlorine levels in your hot tub by regularly checking and testing the water. It is important to make sure the water is safe for use, and you can do this with the strip tests or digital kits.