What is the ideal pool temperature? - Sutro, Inc

What is the ideal pool temperature?

Jumping in a swimming pool with clean, well-balanced water at the right temperature is an incredible feeling. But what is the optimal temperature of a swimming pool? Use this short and quick guide to figure it out, how to measure it, and how to make adjustments. 

The best pool temperature 

According to WHO, the best temperature of pool water is between 78°F and 82°F (26°C and 28°C). Temperatures above 104°F (40°C) are considered uncomfortably hot, and those below 70°F (21°C) are too cold to swim. 

Different people can have their own preference  about what pool temperature is too cold or too hot, so "the perfect pool temperature" is always going to be subjective .  

Let's look at some drawbacks of high and low pool temperatures:

  • Warmer water temperatures offer perfect breeding grounds for algae, bacteria, and other microorganisms.

  • It can cause dehydration, muscle cramps, and overheating of the body.

  • Water that's too hot can cause skin issues.

  • Some pool chemicals do not work under high temperatures.
  • Pool water that's too cold can actually cause shock or hypothermia and  it can result in serious health issues or even a fatality.

  • Water nearing freezing temperatures can damage pool plumbing.

  • Etching and corrosion of surfaces are more likely to happen with cold water.

  • Cold water lowers the LSI (Langelier Saturation Index) of pool water and makes it more corrosive.

How can you measure the pool water temperature? 

The simplest manual method of measuring the temperature of pool water is to use a pool thermometer. You can choose between an analog or digital thermometer, and some models can even connect to your wi-fi.

The Sutro is one of them, it will measure your water hourly but that's not the only thing that it can do.

But it's not only a thermometer, it also has the ability to test pH, chlorine and alkalinity.
Here you can take a look at the Sutro pool monitoring system

Most new pool builds come with automation controls and they include water temperature sensors and water temperature control for heat pumps, heaters, and chillers.  


A pool thermometer

How can you change the pool temperature?

Depending on the season, you may need to raise or lower the pool temperature to extend your pool season or make the water temperature more comfortable. Here’s how you can do that:

How to increase the pool temperature?

  • Use a heat pump which is a more energy-efficient and easy option when compared to pool heaters. You can also use a reversible heat pump to increase or decrease the temperature.

  • Allow sunlight to warm the pool water

  • Use a solar pool cover to heat the water and then retain it. You can also use a heat pump with a regular pool cover for maintaining the generated heat, especially during the night. Adding a cover can reduce heat loss by 50% and also reduce electricity bills. 

How to lower pool temperature?

Use these techniques to lower the pool temperature:

  • Install a pool cooler (pool chiller) to lower the water temperature. You can choose between electric or non-electric variants. Coolers can reduce the pool temperature by 10-15 degrees when used overnight.

  • Add a reversible heat pump to your pool to tackle hot and cold temperatures.

  • Add fountains or a waterfall to your pool, as moving water loses more temperature than still water. Fountains are an inexpensive and easy-to-install solution that enhances the aesthetics and fun of your pool.

  • Add some shade to the pool to protect it from sunlight. You can also look into adding landscaping or planting trees for this. Although, that will increase efforts related to maintenance. 


The most comfortable  pool water temperature falls between 78°F and 82°F (26°C and 28°C) which is suitable for your equipment and also offers incredible health benefits. Heat pumps are the easiest solution to controlling pool temperatures. However, always factor energy efficiency into account to save money on electricity costs. You can also use a pool automation system if maintaining pool temperature is too much trouble for your busy personal schedule. 

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