Recently, Bloomberg reported that investors in massive data centers are making water availability a critical measurement in their decisions — especially in drought-ridden California. Data centers, giant buildings packed with servers that power our virtual world, generate tremendous amounts of intolerable heat. Traditionally, the centers have large cooling systems that require millions of gallons of fresh water. That’s a big problem because water is increasingly in short supply. For the last five years, California has had severe water shortages, forcing Gov. Jerry Brown to issue a series of emergency restrictions.