The question of how much water evaporates from a pool is a concern for pool owners as well as operators of industrial pools, water reservoirs, and wastewater treatment plants. Evaporation is not just an aesthetic problem; it also causes significant costs in terms of water consumption, heating energy, and chemicals. Those who understand the key factors and take targeted countermeasures can reduce water loss by up to 90 percent. This article provides specific evaporation figures, the most important influencing factors, and the proven solutions Euro-Matic has been providing for over 60 years for effectively reducing evaporation.

How much water actually evaporates from the pool each day?

Evaporation in a pool or open basin depends on numerous factors; however, realistic guidelines can be given. In an average private pool with a water surface area of ​​approximately 32 square meters (for example, 8 by 4 meters), between 3 and 8 liters per square meter typically evaporate per day on a warm summer day in Central Europe. This corresponds to a daily loss of around 100 to 250 liters of water, which quickly increases to several thousand liters over the course of several weeks.

In industrial settings, such as service water basins, fire water reservoirs, mining pools, or process water tanks, evaporation can reach up to 12 liters per square meter per day, depending on the climate and water temperature. Over the course of a year, these losses add up to 600 to 1.500 liters per square meter, which translates to millions of liters of water in large facilities.

The most important factors influencing pool evaporation

Anyone who wants to understand how much water evaporates from a pool should be aware of the following main factors:

• Water temperature: The warmer the water, the higher the evaporation rate. An increase of 5 °C significantly increases the loss.
• Air temperature and humidity: Dry, warm air absorbs significantly more water than moist, cool air.
• Wind speed: Wind is one of the biggest drivers of evaporation, as it continuously removes the saturated layer of air above the water's surface.
• Sun exposure: Direct UV radiation heats the uppermost layers of water and accelerates evaporation.
• Water surface: The larger the open area, the higher the overall loss.

These factors have a cumulative effect. A hot, dry, and windy day can increase evaporation three to four times compared to a cool, windless day.

What are the consequences of high evaporation in the pool?

Constant evaporation leads to significant consequences that are often underestimated:

• Higher water costs: Fresh water must be continuously refilled.
• Energy loss: With every liter of water that evaporates, heat energy is lost – on average around 540 kcal per kilogram of water.
• Chemical consumption: Refilling dilutes the water chemistry, requiring additional dosages.
• Ecological damage: In regions with water scarcity, evaporation is a serious sustainability problem.
• Odor formation and algae growth: In industrial basins, an open water surface can promote odor emissions and bacterial growth.

Effective measures against water evaporation in the pool

There are various approaches to significantly reduce evaporation. However, their effectiveness varies considerably:

Classic pool covers and their limitations

Foil, solar, or louvered pool covers are widely used, but have disadvantages: They are cumbersome to handle, must be cut precisely, often block oxygen exchange, and are hardly practical for large, irregularly shaped industrial pools. Furthermore, they require roller or roll-up mechanisms and are maintenance-intensive in the long run.

The effective solution: Cover balls from Euro-Matic

A significantly more flexible and durable solution is the use of cover spheres made of high-quality plastic . These floating hollow spheres cover the water surface in a self-organizing manner and have been proven to reduce evaporation by up to 90 percent. Euro-Matic has been developing and producing these spheres to the highest quality standards for over 60 years – for industry, water management, wastewater treatment plants, and anywhere open water surfaces need to be protected.

The advantages of the cover balls at a glance:

• Reduction of water evaporation by up to 90%
• Reduction of heat loss and therefore heating costs
• Protection from light penetration – counteracts algae growth and chemical degradation
• Odor reduction in industrial and municipal pools
• Adaptable to any pool shape – even with changing water levels
• Low maintenance, durable and UV-stable
• Suitable for drinking water, process water and chemically contaminated media

Where are cover balls used?

The applications are diverse. Euro-Matic supplies customers from the following industries:

• Industrial process water tanks
• Wastewater treatment plants and sewage systems
• Drinking and process water storage
• Mining and acid basins
• fire water storage basin
• Aquaculture and fish farming
• Swimming pools with special requirements

How many balls do I need for my pool?

The required quantity depends on the ball diameter and the pool surface area. For the common size of 80 mm diameter, approximately 175 balls per square meter are needed. However, Euro-Matic offers balls in various sizes, colors, and material qualities – including customized solutions for demanding applications.

Evaporation and energy loss – the underestimated connection

How much water evaporates from a pool isn't just a matter of water conservation. Every liter that evaporates draws heat from the pool. Approximately 580 watt-hours of energy are needed to evaporate one liter of water. With 300 liters of evaporation per day, this equates to a daily loss of around 174 kilowatt-hours of thermal energy – a significant factor in the heating costs of heated pools and industrial basins.

This energy must be replenished through heating, heat pumps, or solar panels. Reducing evaporation therefore saves twice: on fresh water and on energy costs. At the same time, chemical consumption decreases because cleaning agents are not carried to the surface and washed away by evaporating water.

Economic efficiency and amortization

Depending on pool size and energy prices, the investment in pool cover spheres often pays for itself within a single season. An industrial water storage system of 1.000 square meters can save several thousand cubic meters of water annually – plus the corresponding energy and treatment costs. The environmental impact also improves significantly, as less fresh water needs to be drawn and less energy is consumed.

How much water evaporates from the pool – and how to stop it

The answer to the question of how much water evaporates from a pool is clear: significantly more than most pool owners and private users suspect. Several hundred liters per day are not uncommon in summer, and on an industrial scale, millions of liters of valuable water are lost annually. With the right measures – above all, high-quality pool covers – this loss can be drastically reduced. They save water, energy, and chemicals, and make an important contribution to sustainability.

Want to know which pool cover solution is best for your pool? The experts at Euro-Matic are happy to advise you personally. With over six decades of experience in the development and production of hollow sphere solutions, we offer customized concepts for industry, water management, and leisure. Contact us now for a free initial consultation – together we'll find the right solution to effectively stop your water loss.