Find Your Local Water Agency
Where Your Water Comes From
Metropolitan's integrated resources planning strategy calls for a portfolio approach to water resource management that balances imported water with local supplies. Metropolitan imports water from Northern California via the State Water Project and from the Colorado River via the Colorado River Aqueduct. About 45% of Southern California's water supply comes from these two sources.  Southern California relies on various local sources to make up the difference. To ensure adequate supplies for the region, Metropolitan invests in local resource development along with its member agencies and utilizes groundwater banking and transfer program. Metropolitan also manages water demands by promoting and investing in conservation and water use efficiency projects. Southern California's future water supply will largely come from new local supplies such as recycled water and desalination.
Storage and Delivery

Metropolitan is the nation's largest wholesale water agency, providing a reliable supply of imported water to nearly 19 million people and thousands of business in its six-county service area. It operates a complex storage and distribution system that includes an extensive range of reservoirs and distribution pipelines and facilities. The distribution system is comprised of hundreds of miles of pipelines and tunnels, and about 400 service connections of member agencies that in turn provide water across 5,200 square miles.

Since 2009, Metropolitan has doubled the amount of water stored in reservoirs like Diamond Valley Lake in southwest Riverside County, local groundwater basins and in water banking programs in Lake Mead and the San Joaquin Valley. Today, Metropolitan has 13 times more water storage capacity than it did in 1980.

Water Quality

Water Quality


For more than 80 years, Metropolitan has been Southern California's provider of high quality, reliable drinking water that meets or exceeds all federal and state drinking water regulations. Using advanced treatment technologies increased monitoring and adhering to stringent laws and guidelines, Metropolitan works hard to protect the quality of water delivered to the consumer.


To ensure the delivery of a safe and reliable water supply, Metropolitan operates five water treatment plants. On an ongoing basis, Metropolitan tests its water for nearly 400 constituents and performs about 250,000 water quality tests per year on samples gathered from throughout its vast distribution system. Analysis of these samples is undertaken at Metropolitan's state-of-the art water quality laboratory.

•   Water Quality Report         
     (View the report in Spanish)
•   General drinking water information (EPA)
•   California Department of Public Health 

Treatment Facilities

Metropolitan owns and operates five treatment plants that are located throughout Metropolitan's six-county service area and that treat water delivered from the State Water Project and the Colorado River. Four of these plants –F.E. Weymouth, Robert A. Skinner, Robert B. Diemer and Joseph Jensen – are among the 10 largest in the world.