Hot tub safety: temperatures, session times, children and health

Updated 6 November 2026 · By the Hot Tub Hire team

Short answer: Keep a hired hot tub at no more than 40°C, with most people comfortable at 37 to 39°C, and limit sessions to around 15 to 20 minutes before cooling off. Avoid alcohol in the tub, supervise children closely and keep young children out of hot water, and check with a doctor or midwife first if you are pregnant or have a heart condition or other health concern. Keep the cover locked when not in use.

Temperature

Hot tubs feel relaxing because the water is close to or above body temperature, but that also means the body cannot shed heat easily. HSE guidance for spa pools gives 40°C as the maximum. Most adults find 37 to 39°C comfortable, and on warm summer days a slightly lower temperature is more pleasant for longer.

Water temperature	What it means
Up to 36°C	Warm, comfortable for longer sessions and for older children
37 to 39°C	The usual range for adults
40°C	The recommended maximum
Over 40°C	Not recommended, increases the risk of overheating

Hired tubs are usually set to a sensible temperature at delivery. If you change it, do so in small steps and check the display before getting in. On very hot days, some people turn the heater down or off for a while and use the tub as a cooler soak.

Session length

Overheating builds gradually and can catch people out. Signs include dizziness, nausea, a headache, a racing heart and feeling faint. Keep sessions to around 15 to 20 minutes at a time at higher temperatures, get out and cool down in between, and drink water. Anyone who feels unwell should get out slowly, as standing up quickly from hot water can cause light-headedness.

Older people and anyone who feels the heat more should start with shorter sessions at a lower temperature. A hot tub is not a place to fall asleep, so if anyone is getting drowsy, it is time to get out.

Children

Supervise children in and around the tub at all times, even when the cover is on
Many suppliers advise against hot tub use for children under about five
Lower the temperature and shorten sessions for older children
Keep children's heads above the water and away from suction fittings
Lock the cover whenever the tub is not being used
Make sure children cannot climb in when adults are not watching

Even when the tub is not in use, a hot tub is a drowning risk for young children. Fasten every cover clip, keep steps away from the side and do not leave children alone in the garden with the tub, even for a moment.

Health conditions and pregnancy

Hot water raises body temperature and affects blood pressure and heart rate. People who are pregnant, have heart or circulation problems, high or low blood pressure, diabetes, epilepsy, or who take medicines that cause drowsiness or affect blood pressure, should check with their GP, midwife or pharmacist before using a hot tub. NHS advice during pregnancy is to avoid overheating, which is why many people choose not to use hot tubs while pregnant.

Anyone with an open wound, a skin infection or a stomach upset should stay out of the tub, both for their own sake and to avoid spreading infection to others.

If you are unsure whether a hot tub is safe for you, try a short session at a lower temperature, around 36°C, and get out at the first sign of feeling unwell. Medical advice always comes first, and there is no harm in sitting on the edge with your feet in the water instead.

Alcohol

Alcohol and hot water make each other's effects stronger. Both widen blood vessels and can lower blood pressure, which makes dizziness and fainting more likely, and alcohol slows reactions and increases the risk of drowning. The safest approach is not to drink while in the tub. At parties, keep glass away from the tub, use plastic cups and keep anyone who has drunk heavily out.

Recreational drugs and some prescription medicines can have similar effects, causing drowsiness, low blood pressure or confusion in hot water. If anyone has taken something that makes them sleepy or unsteady, keep them out of the tub. A sober adult should keep an eye on things at any party where the tub is in use.

Electrics and the cover

Plug the tub directly into an RCD-protected outdoor socket, not a standard extension lead
Test the RCD before use if the tub or socket has a test button
Keep the plug, socket and cable dry and off the ground
Switch off at the socket before removing the filter or touching the pump unit
Do not use the tub during a thunderstorm
Keep the cover fastened and locked when the tub is not in use

Before every session

Check the temperature on the control panel
Test the water and make sure the sanitiser is within range
Shower or rinse off beforehand to keep the water cleaner
Keep a towel, water to drink and somewhere to cool down close by
Agree who is keeping an eye on children and guests