Pool evaporation: how much water are you really losing?
Evaporation is the leading cause of a drop in the water level of a pool. A natural and unavoidable phenomenon, it varies considerably with the weather and the layout of your pool. Here is everything you need to know. Evaporation in your pool is normal, and has to be compensated for regularly.
Why does the water in your pool evaporate?
Evaporation occurs at the surface of any body of water exposed to the air. Heat turns liquid water into water vapour, which escapes into the atmosphere. It is a permanent physical process that continues even at night — just more slowly. For an evaporation calculator (in French): see this page
The factors that influence evaporation
Temperature and sunshine
The hotter it is and the stronger the sun, the faster the evaporation. In midsummer during a heatwave, a pool can lose up to 3% of its water volume per day through evaporation alone.
Wind
Wind speeds up evaporation considerably by constantly sweeping away the water vapour above the surface. A pool exposed to the wind loses much more water than a sheltered pool at the same temperature.
Air humidity
In dry weather the air can absorb more water vapour — so evaporation is stronger. In humid or rainy weather it is naturally reduced.
The exposed water surface
Evaporation is proportional to the surface area of the water, not the volume of the pool. A large pool loses more water in litres than a small one, but the level drops by the same number of centimetres in both.
Can evaporation losses be calculated precisely?
In theory yes, but in practice it is very difficult. There are many parameters and they change hour by hour: air and water temperature, sunshine, wind speed, humidity. Just remember that in summer, a loss of 1 to 3 cm per week through evaporation is perfectly normal.
Protect your equipment this season
NivOmatic keeps your pool level constant 24/7, with no electricity and no supervision. Installed in 2 minutes. Made in France — €129.
Free delivery in France · 2-year warranty · After-sales service in France
Evaporation or leak: how can you tell the difference?
If your pool loses more than 3 cm per week, there may be a leak. The bucket test is the simple way to check in 24 hours: fill a bucket with water, place it on a step in the pool and compare the drop in level after 24 hours. If the pool has lost more water than the bucket, you probably have a leak.
→ Read our complete guide: Pool leak — how to carry out a simple diagnosis in 24 hours
The solution: compensate for evaporation automatically
Evaporation is unavoidable. What is far less so is having to monitor these losses and make up for them by hand every week.
NivOmatic monitors and maintains your pool level continuously. As soon as the level drops — whatever the cause — it opens the water supply and closes it again as soon as the desired level is reached. Automatically, with no electricity and no action on your part.
Compensates for evaporation, splashing and liner losses
Works 24/7, even while you are on holiday
Made in France for over 15 years
Installed in 2 minutes, 2-year warranty
