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Frequently Asked Questions

Below are answers to some of the most frequently asked questions regarding water quality that we receive. If you have other questions about water quality issues, please contact us.

Where does our water come from?

Between 85 and 90% of our drinking water is a blend from the Colorado River and Northern California. About 10 to 15% of the City's drinking water supply is made up of runoff from local rainfall that is captured in our reservoirs. For more information, see the Water Sources web page.

Service Areas

Where is our drinking water treated?

The City has three water treatment plants, and where your water is treated depends upon what part of the City you live. South San Diego receives water from the Otay Water Treatment Plant, central San Diego's water comes from the Alvarado Water Treatment Plant, and north San Diego gets water from the Miramar Water Treatment Plant. For more information, see the Our Water Treatment Process web page.

Does the City's water supply contain fluoride?

The City of San Diego began water fluoridation in February 2011. California state law requires water agencies with more than 10,000 water service connections (which includes the City of San Diego) fluoridate their drinking water supplies. If you have health questions or concerns regarding fluoride, please contact your physician and/or dentist. For more information, see the Water Fluoridation web page.

What do you test for in my drinking water, and where can I get those test results?

The California Department of Public Health requires water agencies to test for certain contaminants. Each year the City publishes its annual “Drinking Water Quality Report” with results from these tests, as well as other useful information. The report and additional Tables 5 and 6, can be found on the Water Quality web page.

What is the hardness of my water?

Typically, drinking water in San Diego averages about 15.4 grains per gallon (gr/gal), or 263 parts per million (ppm); and, depending upon water demand and the area of the City you live, can range from 13.4 to 19.0 gr/gal, or 229 to 325 ppm. For more information, see the Water Hardness web page.

Is lead a hazard in our water?

No. We have tested water in homes that might have the greatest risk of lead in the water, and have found no hazardous levels of lead. Our water is not corrosive so it is not likely to dissolve lead from plumbing fixtures. Lead pipe is not used in any of the City's water utility systems.

Does the City test for Cryptosporidium in the water supply? Is there a concern for the general public or for people with compromised immune systems?

Cryptosporidium is a potentially infectious microscopic organism that has been found in water sources in other parts of the country. There is a very low, if any, risk to the general public of contacting cryptosporidiosis from drinking water served by the City's Public Utilities Department. However, state health officials recommend that any person with a severely compromised immune system, especially those with AIDS, should consult their physician about taking measures to avoid the risk of infection from all potential sources. Persons in other groups with compromised immune systems, such as organ transplant or bone marrow recipients and chemotherapy patients, should also contact their physician. The City routinely tests our source waters and our treated water for Cryptosporidium. We have not found any in the treated water sent to our customers.