Too hot in the hot tub?

How hot is hot enough, how hot is too hot?

We search for an answer to the question “What temperature should I set my hot tub at?”

In the depths of winter, the feeling of lowering yourself into the warm and inviting water of your hot tub is one to be savoured.  If you’re anything like us, the temptation is to set the temperature to the maximum setting and leave it there.  Simple?  But choosing the right temperature depends not only on your personal preference – your families or guests health & safety, not to mention your budget will need to be considered as well, before you find the goldilocks zone of not too hot, not too cold that works best for everyone.

Adjusting the heat of your hot tub is a straightforward affair – most have a simple push button menu on the control panel while some models allow you to control your hot tub heat settings from the convenience of an app on your phone, tablet or PC.

Hot Tub Touch Screen Control Panel

The maximum temperature setting as stated in the European Standard for domestic spas and hot tubs (BS EN 17125) is 40° C / 104° F.  No reputable hot tub brand will manufacture a tub that exceeds this setting.  Even though your hot tub will have a temperature limiting device, keeping a separate thermometer handy is best practice – that way you’ll be able to quickly and easily confirm your spa water temperature and identify any potential problems, such as overheating or heating failure, before you get in the water.

Is 40°C too hot?

As your body temperature increases to the point where it reaches or exceeds 39° C / 103° F, there is an increasing danger of developing several conditions related to hyperthermia (excessively high body temperature), ranging from mild to seriously life threatening.  These may include:

  • Heat rash
  • Heat cramps
  • Heat stroke
  • Heat exhaustion


older couple in hot tub

The risk of serious complications becomes even higher for older people, younger children, pregnant women, and those with chronic illnesses or conditions such as a heart condition, high blood pressure and diabetes.

Even if you’re in overall good health, spending excessively long periods of time in hot water can be dangerous.

What are the recommendations for children using a hot tub?

HSG 282 (published by the UK Health & Safety Executive) states that children under 4 years of age should not be allowed to use a spa.  In the USA the CDC (Centre for Disease Control & Prevention) sets the minimum age at 5.  This is partly due to water safety, but also has an element of temperature consideration – as children don’t have the same heat tolerance as adults. Their smaller bodies and thinner skin make them more susceptible to heat.


At the maximum recommended water temperature, children should not use the hot tub for more than 5 minutes at a time. Dropping the water temperature by a few degrees – to 36.5° C / 98° F will allow for a longer soak, but even this should be limited to a maximum of 15 minutes.  To reduce risk of children overheating, sitting on a booster cushion is also a good idea – as in this way young children avoid full body immersion, allowing their bodies to regulate heat more effectively.  Never allow children to use a hot tub unsupervised.

Can I use a hot tub if I’m pregnant?

If you are, or may be pregnant, the current NHS advice is to avoid using hot tubs due to the risk of over-heating, fainting or dehydration.  It’s possible that a significant rise in your core temperature could be harmful in pregnancy, particularly in the first 12 weeks.  With regard to water temperature the NHS website makes the following statement, “If you’re exercising in water, such as at an antenatal class, the temperature of the water should not be above 32° C.

If you’re using a hydrotherapy pool, the temperature should not be above 35° C.”  If you’re past the first trimester and you feel you want to use the hot tub, do so only after getting your doctor’s approval, and use the tub for no more than 10 minutes at a time and allow for plenty of cooling off in between sessions.

How do I find the right hot tub temperature?

Having taken into account the above safety considerations, your perfect spa soak temperature will probably vary depending on the time of year – for example on a hot summers afternoon, you might enjoy a refreshing cooler dip than you will for a mid-winter soak as snow is falling around you.

A good starting point is the average normal body temperature, 37° C / 98.6° F.  If it’s too chilly, slowly increase the temperature until you’re comfortable.  The stress reducing effects of your spa are lessened as water temperature drops – so don’t go too low!

Can I save money by reducing the temperature of my hot tub?

How much energy your hot tub consumes heating the water was probably an important consideration when deciding whether to buy a tub.  Premium hot tubs have high levels of insulation and you can supplement this with a floating heat retention cover and a good quality, good condition hot tub cover. You might also think about lowering your hot tub’s heat setting when you’re not using it for longer periods to cut your energy costs.

But beware, if you use your hot tub regularly and lower the temperature setting between each use, you might actually increase your energy costs.  This is because reheating the hot tub water each time not only burns extra energy, but also your spa’s heating element has to work harder to raise the water temperature than it does to maintain it. This can wear it out more quickly than a more balanced load, perhaps requiring you to replace it more often if it burns out.

I’m going away on holiday, can I lower the temperature of my hot tub?

If you don’t plan to use your hot tub for a longer period of time, dropping the temperature is a great idea as this can help you avoid a high energy bill when you return.  Most hot tubs have an economy or holiday setting that will maintain much lower water temperatures.  Just beware if ambient temperatures are around freezing, setting the spa too low or even turning the heater off risks burst pipes and potentially some expensive damage to pumps and other hardware.

So having settled on the best blissful temperature for you, what’s left now?  Just enjoy relaxing safe in the knowledge that you are enjoying the very best hydrotherapy for mind and body!

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