Given the water scarcity crisis, preserving existing water resources and preventing evaporation from open reservoirs is essential. Two main methods for preventing water evaporation from ponds and pools are discussed below.
Suspended Covers
These are large, horizontal, sail-like structures stretched above the water surface and supported by external steel cables. Suspended systems are classified according to their size and cover weight. Their materials range from porous materials to impermeable plastics.
The cover reduces evaporation by blocking solar radiation, thereby reducing the energy reaching the reservoir’s water surface. This lowers the surface temperature and evaporation potential. It also reduces evaporation by lowering the vapor pressure gradient at the surface. Evaporated water can also return to the surface. The effectiveness of this method depends on how the cover is installed and its water vapor transmission rate.
Floating Covers
Three types of floating covers have been introduced to the market: hexagonal tiles, balls, and hexahedral elements. All three were introduced by Advanced Water Treatment Technology (AWTT).
Modular Hexagonal Floating Covers
This model covers 99% of the surface and reduces water evaporation by 95%. It is resistant to wind. Its evaporation-reduction mechanism relies on limiting heat transfer through two combined factors: the low thermal conductivity of the air trapped inside the tiles and that of the plastic itself. Air trapped between the tiles also helps reduce heat transfer.
This thermal insulation reduces light and heat absorption, thereby reducing evaporation. The tiles can be moved aside and adjust to changes in water level while maintaining surface coverage. Completely covering the water surface makes the pool less attractive to animals and discourages them from drinking its water.
Another version of the hexagonal tiles is filled with polyurethane foam instead of air. It offers the same advantages but provides greater thermal insulation.
Floating Ball Covers
These balls measure 4 inches in diameter and cover 91% of the water surface. Heat transfer is reduced through the low thermal conductivity of the air trapped inside the balls and the plastic itself. This model reduces evaporation by 90%.
A ballasted version is also available, with 30–50% of each ball submerged, making it resistant to wind. Floating ball covers do not interfere with the installation of stationary or moving equipment in the pool.
Hexahedral Floating Covers
This product combines features of the two previous models. It covers 99% of the surface, is symmetrical in all directions, and is resistant to wind. It does not restrict the installation of stationary or moving equipment and adapts to rising or falling water levels.
All these products are made from high-density polyethylene (HDPE), come with a 25-year warranty, and prevent algae growth and unpleasant water odors. They are quick and easy to install and maintain, and resistant to snow and cold.
