Water is like electricity. Most people don’t notice it until it goes away. But there are big issues with big price tags facing Silicon Valley’s largest water agency, a district that has spent the past few years immersed in conflict and controversy. Three of the seven seats on the board of the Santa Clara Valley Water District are up for re-election this fall. The district, based in San Jose, is a government agency that provides drinking water and flood control to 2 million people in Santa Clara County.  As a wholesaler, the district buys water from state and federal agencies. It regulates local groundwater, operates 10 reservoirs and sells water to more than a dozen cities and private companies, who in turn sell it to homes and businesses. The district’s directors serve four-year terms and earn about $60,000 a year.