What Is the Perfect Pool Temperature?

Written by Michael Dean
December 21, 2023

swimming pool next to a thermometer

Nothing is better than taking a dip on a hot day. But what if the pool temperature is too warm to be comfortable — or worse, it’s so warm that bacteria, algae, and other microorganisms start to grow? On the other hand, what if your pool water is so cold that jumping in affects your breathing and makes your skin feel like it’s on fire?

The perfect pool temperature is more important than you think. Here’s why.

Main Takeaways

  • Swimming pool temperature is important because there are hot water nuisances like algae and bacteria and there are cold water issues like potential difficulties with breathing.
  • As a general rule, keep the pool temperature between 77 and 84 degrees.
  • To measure pool temperature, use a pool thermometer.
  • Control your pool temperature with a pool heater in order to provide comfort, improve pool safety, boost sanitation efforts, and save energy and money.

Why Swimming Pool Temperature is Important

It’s not a good idea to let your pool temperature fluctuate with the outside temperature. Temperature is a critical factor for all living things. This includes the critters that want to live in your pool.

Hot Water Nuisances

Specifically, we’re talking about heat-loving microorganisms called algae and bacteria. Algae are microscopic organisms that photosynthesize. Algae live in your pool if there’s a green film covering the pool or see clumps of green, yellow, or brown dispersed throughout the water.

Algae most notably discolor your pristine pool, but they can cause bathers to itch, give the pool a nasty odor, and clog the water filtering system, according to a report from Michigan State University.

Bacteria can also cause problems in your pool. They’re less visible than algae, but bacteria are more likely to get you sick than algae.

According to the MSU report, “the bacteria found in swimming pools is generally dangerous and should be controlled. Certain bacteria produce poisonous substances (toxins) that can cause diseases, such as lockjaw, or food poisoning in humans.”

Keeping a constant pool temperature keeps potentially harmful microorganisms at bay.

Cold Water Dangers

Cold pool temperatures cause issues in addition to hot ones. The National Center for Cold Water Safety states that water temperatures below 78 degrees Fahrenheit can start to affect breathing in swimmers. This is especially true for people who already have impaired respiratory function, such as those with COPD and asthma.

Swimmers will find breathing progressively more difficult as the temperature drops from 70°F to 60°F. It’s not comfortable at first, but your body will adjust.

The danger lies in jumping into a pool between 50°F and 60°F. Unless you spend lots of time swimming in icy cold waters, the unacclimated body treats water temperatures between 50°F and 60°F as it would at 35°F, according to The National Center for Cold Water Safety.

Such cold water can cause total loss of breathing control, meaning swimmers will start gasping and hyperventilating. The body will go into cold shock too. This can cause the inability to swim effectively, which increases the likelihood of drowning.

And jumping into a pool from 40°F to 32°F will feel painful. Not only do you expose yourself to the inability to breathe and swim, but your skin feels extreme cold as heat. Your skin will feel like it’s burning.

Please note that it takes a pool 8 to 12 hours to acclimate to outdoor temperatures. If you or your child decides to jump in a pool at 3 pm when it’s 80°F, but night temperatures reach 40°F, you could face swimming-related injuries.

Pool temperature poses real safety risks, whether through algae, bacteria, or directly jumping into the water. That’s why you should carefully monitor your pool’s temperature.

What is the Ideal Pool Temperature Range?

Adults will generally prefer pool temperatures in the upper 80s. The Mayo Clinic finds that the most comfortable pool temperature range is between 83°F and 88°F.

Pools used for physical therapy must also be at a higher temperature, ideally around 86°F. Warmer temperatures also benefit those who swim to relax muscles or to make stretching exercises easier.

Young children need warmer water. Pool temperatures for infant- or preschool-aged children must be around 90°F to 93°F, according to the Red Cross.

A slightly cooler pool temperature will be better for exercise or competitive swimming training. The Olympics keep their pools between 77°F and 82°F, allowing swimmers to stay cool while exercising for hours without impairing their breathing.

As you can see, the ideal pool temperature range depends on what you plan to use the pool for. But as a general rule, keep it about 77°F to 84°F.

How to Measure Pool Temperature

Forget toe-dipping. One of the most reliable ways to measure pool temperature is through pool thermometers.

Many pool thermometers float atop the surface of the water, getting a consistent read on the pool’s core temperature. Some pool thermometers use alcohol up a numbered scale to depict the pool’s temperature (called analog thermometers), while others use an LCD screen to show you the exact temperature (digital thermometers).

Other pool thermometers are wireless. You can place one component in the pool to gauge its temperature, transmitting the data to another gadget that shows the pool’s temperature. Those who don’t want to bend down to get their pool thermometer will find the wireless types convenient.

Some pool thermometers require no energy at all, such as analog thermometers. Others use the sun to power their screens. Others use batteries to depict the time. Each has its pros and cons, so it should depend on your preference for which thermometer you get.

How to Control Pool Temperature

The best way to control pool temperature is through a pool heater. These pumps have built-in thermostats to gauge the pool’s temperature. Then it regulates the pool temperature to your desired temperature, like your air conditioning unit. Some heaters even come with pool chiller attachments.

The pool pump works until your desired temperature is reached. It will then turn off and only turn back on when the water temperature strays by more than two degrees.

Some pool pumps also have timer features. You can set a clock to turn on the pool’s heating or cooling, allowing you to reach your desired temperature when you’re most likely to swim. Timers also allow you to save energy by turning off your pool’s pump in the middle of the night when you’re not likely to swim.

If you’re interested in getting a heater, check out my research on the best inground pool heater.

Benefits of Controlling Pool Temperature

Now that you know how to control your pool’s temperature, here are reasons why you should do it.

Comfort. Who wants to feel that initial shock to the system when jumping into a pool? You can instead cannonball into a perfectly warm pool by maintaining its temperature.

Improves pool safety. Keeping a constant temperature prevents bacteria and algae from growing in hot temperatures. It also reduces the chance of encountering breathing issues due to cold water temperatures.

Boosts sanitation efforts. Maintaining constant pool temperature improves chlorine, saltwater, and other pool sanitation measures. Keeping consistently cool pool temperatures also keeps algae and bacteria away.

Saves energy and money. Having pool pumps with timer systems lets you select certain times you’ll heat your pool rather than keeping it on constantly. Setting such time limits saves energy expended on heating/cooling your pool, which translates to money saved.

Get My Free Pool Care Checklist

Download my free, printable pool maintenance checklist to help you accomplish regular pool care tasks for any type of swimming pool.

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The perfect pool temperature depends on your size, age, and gender. It also depends on whether you plan to use your pool for leisure, physical therapy, training an infant to swim, or exercise.

Once you find the perfect pool temperature, maintaining it depends on the type of pool pump you have.

Questions? Feel free to drop me a note, and I’ll help in any way we can.

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