A new law requires that virtually all multiple-family complexes built after Jan. 1, 2018, must have water meters on each unit. “Eighty percent of the 15.6 million Californians living in apartments or other multifamily housing are not billed for their water use, meaning nearly a third of the state’s population doesn’t know how much water they’re using or how much they are charged based on their use,” Sen. Lois Wolk, who authored the bill, said in a statement. Gov. Jerry Brown signed Wolk’s Senate Bill 7 on Monday.