The lack of usable water worldwide has made it more valuable than oil. The Bloomberg World Water Index of 11 utilities returned 35 per cent annually since 2003, compared with 29 per cent for oil and gas stocks and 10 per cent for the Standard & Poor's 500 Index.
The United Nations estimates that by 2050 more than 2 billion people in 48 countries will be short of water.
"There is only one direction for water prices at the moment, and that's up," said Hans Peter Portner, who manages a US$2.9 billion ($4.7 billion) Water Fund at Pictet Asset Management in Geneva.
The fund jumped 26 per cent last year, and Portner forecasts annual returns from water of 8 per cent through 2020.
General Electric chairman Jeffrey Immelt says "scarce" clean water worldwide will more than double the revenue he gets from water purification and treatment to US$5 billion by 2010.
"This will be a big and growing market for a long time," as governments struggle to bring water to 4 billion people who live in areas of profound shortage, Immelt, 50, said at the company's annual meeting in Philadelphia in April.
