Although Los Angeles city water customers paid extra for costly imported water during the five-year drought, their water bills will drop very little now that the Department of Water and Power has a plentiful supply of its own, officials said. The DWP surplus does not translate into big savings for individual bill payers because water rates were restructured last year.  The new rates are intended to raise more money for water system improvements.”The money that would have gone to purchased water is now going to infrastructure investment,” said DWP spokeswoman Amanda Parsons.