Hot Tub Water Temperature: How Hot is Too Hot?


Much like pool temperature, hot tub water temperature is something that is always a frequent topic of debate among users. Since everyone generally runs at an internal body temperature of approximately 98.6° F, the water needs to be warmer than that to get the most out of the hydrotherapy that is provided by a good soak in a hot tub. But what exactly is the most optimal hot tub water temperature?

First, a little bit about how your hot tub comes programmed.


The Hot Tub Standard: 104°

Most all modern hot tubs come programmed to have a high-limit of 104° Fahrenheit, although they have the ability to run as low as 80°. The National Spa and Pool Institute considers 104° to be the maximum temperature that is considered safe for adult use therefore, spa controls have a limit that is set to keep water from heating past that number.

It can be difficult to compromise with someone who likes the hot tub hotter or cooler than you prefer. However, most people who have a hot tub keep it in a range between 100°-the max of 104° Fahrenheit. This number varies depending on any health conditions, age, or pregnancy restrictions.

Since the high-limit that keeps the tub under 104° can become damaged and lead to higher temperatures (particularly in older hot tub units), you want to have a back-up means of monitoring your hot tub water. Something as simple as a floating hot tub thermometer is a great way to double check the safety of your water temperature. Some heating elements can go on the fritz and if your high limit switch has stopped working and you aren’t getting a proper read on your topside panel, there’s a chance you can be getting yourself into unsafe water. Water at 110° can be really dangerous. Protect yourself with something as simple as a thermometer that should ALWAYS be checked before getting into your hot tub.

Different Conditions, Different Temperature

While the optimum temperature for hydrotherapy purposes is between 102°-104°, not everyone fits into that category. If you have health concerns like heart disease, diabetes, high blood pressure, you should consult with your doctor to see what a safe temperature is for your hot tub. You will probably get a minute restriction, too—somewhere in the neighborhood of 15 minutes or under.

PREGNANT WOMEN are also cautioned to be very careful in the hot tub during gestation, particularly during the first trimester. High external temperatures for extended periods of time lead to problems with the fetus, resulting most commonly in neural tube defects. If you are pregnant and wanting to relax in the water of your hot tub, turn the temperature down to about 100° and limit your soaking time to around 20 minutes. Your body temperature can reach 102° F in as little as 20 minutes which can lead to health issues, so just listen to your body and get out if you feel yourself overheating.

CHILDREN also have some constrictions when using the hot tub. If you’ve ever been to a hotel, there’s usually a sign signifying that it is inappropriate for use by children under 12 years old. While that’s typically a liability issue for the establishment, there is some truth to it. Children are less able to endure acute temperature changes and can become dehydrated in too-hot water rather quickly. Much like the guideline for pregnant women, most children should not get into water that is over 100° F. Also make sure they aren’t dunking their head under water and you’re limiting their time to 20-30 minutes at a time.

Energy Savings?

One question we get all the time is whether it’s a good idea to lower hot tub temperature after use and then turning it back up before getting in again. If this is just for short periods of time, this is NOT a recommended energy saving tactic. In fact, it does quite the opposite. A hot tub with a thermal blanket and well-sealing hot tub cover does a good job of maintaining its temperature; it’s the constant raising and lowering that is going to be a drain of energy. In addition, this puts strain on your heating element and the circuit board. Unless you will be away for an extended period of time (summer, etc.), turning down the hot tub will save little to no energy. Having a good spa cover that is well-insulated will keep your costs down and heat sealed in.


Sight, Smell, Touch Test

If you’re using a hot tub at a hotel or a friend’s house over which you don’t have any control, make sure it passes the eye and smell test. According to the CDC, you should ALWAYS check the tiles to make sure there’s no unsightly buildup—if they’re not smooth, don’t get in. Take a good whiff, too. If there’s a strong smell (chemical or otherwise), rethink your dip. The temperature should also never exceed 104° so double check with the in-water thermometer, if possible. If it passes those three tests, you’re good to go.
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