Millions of cubic meters of water are lost annually through water evaporation. With predicted higher maximum temperatures associated with anticipated global warming evaporative losses will likely increase.
PUC, the national water agency of Singapore, tested WaterSavr, which should reduce surface water evaporation rates by 20–50 % without adverse environmental effects or impacts on water treatment, in one of their reservoirs.

WaterSavr is a blend of calcium hydroxide and food grade steryl and cetyl alcohols. The odourless white powder automatically and rapidly spreads into an invisible, single molecule thin film over the surface of a body of water due to the natural ionic repulsion of the calcium ions that are dissociated on the calcium hydroxide’s contact with water. This invisible film automatically reforms from wind, wave, or human activities, and is fully biodegradable within approximately 48–72 hours.

The data analysis from evaluation studies in Singapore showed a more than 30 % mean total reduction of evaporation by daily application of WaterSavr. Subsequent cost-efficiency analysis indicates that it would be cost-effective to implement at a larger, nation-wide scale.

• Water21 2010, October, page 21.
  International Water Association (IWA)