What Is the Minimum Temperature for a Hot Tub?

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There are a few reasons why you might be wondering how low your spa can go: maybe you want to know what a comfortable temperature is for regular use, or perhaps you're not sure how cold your hot tub should get while you're not using it over the winter.

The minimum desirable temperature for a spa can depend on a number of factors including season or climate, personal preference, budget and safety. Let's dive into what this means for several potential situations.

What is the minimum comfortable temperature for use?

Most manufacturers recommend setting your hot tub to maintain a balmy 100°F the majority of the time. This strikes a balance between usable temperature and energy efficiency.

However, the majority of hot tub users prefer water temperature in the 100°F-102°F range, so you might have to crank it up a degree or two when you want to use the spa.

What you consider a comfortable minimum temperature will also depend on your climate, of course. So on a hot summer's day in Texas, you'll want much cooler water than if you were hot tubbing in the snow in the middle of winter in Toronto.

If you’re not sure what's comfortable for you, experiment by setting your spa at body temperature (98.6°F or 37°C) initially. Then if that feels too cold, increase the heat in gradual increments until you find your comfort zone.

It's also worth noting that the CDC recommends a maximum of 104°F. You shouldn't need to leave your tub this warm all the time, but it's useful to know to help you avoid potential health risks.

Hot tub temperature for children

Kids have a lower tolerance for hot temperatures. In fact, children under age 5 should not be in hot tubs over 95°F, and should only remain in hot tubs for 5-10 minutes at a time.

So, if you have kids or grandkids, know that the comfortable minimum for them may be significantly cooler than what it would be for you.

What temperature should I set my hot tub when on vacation?

When you're away from home, you can set your spa to maintain a lower temperature, which can save energy and money.

If you're just going away for a few weeks, most hot tubs have a setting designed for exactly this. It will maintain the temperature at around 15 degrees lower than normal, and is often called something like or 'economy' or 'sleep' mode—so look out for this in your manual.

When you get back from your trip, simply set the spa back to standard mode, and it'll heat back up to your regular temperature.

How cold is too cold for a hot tub?

If you live in a colder climate and experience freezing winter temperatures, you'll need to decide whether you want to use your hot tub throughout the winter months.

If you don't plan to use it over this extended period—or at least not enough for it to be worth the elevated electricity costs—consider winterizing it.

You should never let your hot tub freeze, as this can burst pipes and damage equipment. Instead, winterize it properly by draining and cleaning the spa, then remove all water from the pipes before leaving it off over winter.

Can you use a hot tub with cold water?

Most hot tubs will typically go as low as 80 degrees, which essentially turns the heater off. So if you live in tropical or desert climate, it's totally okay to turn the temperature down as low as it will go.

But what if you want even colder water?

Temporary ways to cool down your spa

If 80°F isn't cold enough, you can always top up the spa with cold water from the hose, or even add some ice for an instant fix on a very hot day.

Just be sure to check and adjust your water balance after though, as introducing new water could change your pH, alkalinity and calcium hardness.

Maintaining cold water in hot tubs

The above solutions work as temporary ways to cool the water, but there are also more consistent ways to keep the water cool.

Some spa brands like Caldera and Hot Spring offer integrated CoolZone™ hot tub cooling systems as an add-on.

Another manufacturer to check out is Atera Spas. Their spas are built with patented cold-to-hot technology, and they also offer dual-zone swim spas if you want a warm hot tub and cool swim spa in one.

With some of these systems, you can get your spa as low as 60 degrees.

How do you balance energy consumption and spa temperature?

Energy usage is a concern for many hot tub owners, both for ecological and financial reasons.

You might think you should lower the temperature of your spa when it's not in use. Less heating means less energy used, right? Unfortunately, this isn't as wise as a decision as you might think.

Turning down the temperature between uses—especially if you take a dip several times a week—can actually increase energy costs.

Did you know? Heating a spa from cold to hot actually puts more strain on the heating system and and consumes more energy than it takes to simply maintain the temperature at a consistent warm level.

That's why 100°F is a perfectly reasonable temperature to leave your spa, whenever it's in relatively frequent use.

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