GENEVA (Reuters) - Investors who have seen energy prices rocket due to scarce supplies are starting to wager that forecasted shortages will cause the value of water to skyrocket, offering big gains to companies active in the sector. Unlike globally traded commodities like oil, gold or wheat, water tends to be priced locally by authorities who provide it as a public good, generally drawing from nearby sources such as lakes or river basins. "Water is not treated like oil because you usually do not transport it over very long distances," said Wolfgang Grabs, who heads the water resources division of...