Contra Costa Water District

Water sources for both tap and bottled water include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over land surfaces or through ground layers, it dissolves naturally occurring minerals and, in some cases, radioactive materials, while also potentially collecting substances from animal presence or human activities.

Potential contaminants in source water include:

• Microbial contaminants: Viruses and bacteria from sewage treatment facilities, septic systems, agricultural operations, and wildlife.
• Inorganic contaminants: Salts and metals occurring naturally or resulting from urban runoff, wastewater discharges, oil/gas production, mining, or farming.
• Organic chemical contaminants: Synthetic and volatile organic compounds from industrial processes, petroleum production, gas stations, stormwater runoff, and septic systems.
• Pesticides and herbicides: From various sources including agriculture, urban stormwater runoff, and residential usage.
• Radioactive contaminants: Naturally occurring or resulting from oil/gas production and mining activities.

To ensure tap water safety, the U.S. Environmental Protection Agency (USEPA) and State Water Resources Control Board establish regulations limiting contaminant levels in public water systems. State Board regulations also set similar standards for bottled water to protect public health. All water, including bottled water, may reasonably contain at least small amounts of some contaminants, which doesn't necessarily indicate a health risk. For more information about contaminants and potential health effects, contact the USEPA's Safe Drinking Water Hotline (1-800-426-4791).

Notice for vulnerable populations: Some individuals may be more susceptible to contaminants than the general population. Immunocompromised persons, including those undergoing chemotherapy, organ transplant recipients, people with HIV/AIDS or immune disorders, some elderly individuals, and infants may face higher infection risks. These individuals should seek advice about drinking water from their healthcare providers. USEPA/CDC guidelines on reducing Cryptosporidium and other microbial contamination risks are available from the Safe Drinking Water Hotline (1-800-426-4791).

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