Water Quality

The delivery of safe water to the San Diego County Water Authority's 24 retail member agencies and their customers is the top priority for the Water Authority. Regular water quality monitoring and the use of online monitoring equipment ensure that the Water Authority is delivering high-quality, safe water to its member agencies 24 hours a day, seven days a week.


Potable water supplied by the Water Authority to its member agencies comes from three primary sources: the Claude "Bud" Lewis Carlsbad Desalination Plant, the Robert A. Skinner Water Treatment Plant in Riverside County - owned and operated by the Metropolitan Water District of Southern California - and the Twin Oaks Valley Water Treatment Plant north of San Marcos.




Here are the 2018 test results for each facility: 

Claude “Bud” Lewis Carlsbad Desalination Plant
Robert A. Skinner Treatment Plant in Riverside County
Twin Oaks Valley Water Treatment Plant

In addition to the Water Authority, other agencies that own and operate treatment plants within the county include:

•    Escondido (City of) - joint ownership with Vista Irrigation District
•    Helix Water District
•    Oceanside (City of)
•    Olivenhain Municipal Water District
•    Poway (City of)
•    San Diego (City of)
•    Santa Fe Irrigation District - joint ownership with San Dieguito Water District
•    Sweetwater Authority (operating for South Bay Irrigation District and National City)

Whether the water is treated by MWD, the Water Authority, or a local agency, all treated water served in San Diego County meets or exceeds rigorous state and federal water quality regulations.

Additional Information:

For additional information on fluoridation, click here.
For additional information on lead testing, click here.


Metropolitan Water District: water quality
California Department of Health Services (DHS)