The Los Angeles City Council voted 8-4 on Wednesday to approve a 3-percent increase in water rates for residential and business customers.
DWP officials say it needs the increase to fund nearly $600 million in upgrades to drinking water reservoirs and bring them in compliance with federal guidelines.
New Environmental Protection Agency guidelines require the DWP to cover its reservoirs or quit using them for drinking water.
DWP chief Ron Nichols said violations could cost taxpayers up to $25,000 per each day the city is out of compliance.
By spring, the average customer will see his or her bill go up by about $1.71.
Council members Jan Perry, Mitchell Englander, Paul Koretz and Dennis Zine opposed the rate increases.
The Department of Water and Power is the nation's largest publicly owned utility.
City News Service contributed to this story.