What Contaminates Are in Water

Water Source


The City of Monterey Park's source of water is groundwater that is precipitation that infiltrates through the soil. As water travels over the surface of the land and through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity. Contaminants that may be present in source water include:
  • Microbial contaminants, such as viruses and bacteria that may come from sewage treatment plants, septic systems, agricultural livestock operations and wildlife.
  • Inorganic contaminants, such as salts and metals that can be naturally-occurring or result from urban storm water runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.
  • Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban storm water runoff and residential uses.
  • Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production and mining activities.
  • Organic chemical contaminants, including synthetic and volatile organic chemicals that are byproducts of industrial processes and petroleum production, and can also come from gas stations, urban storm water runoff, and septic systems.
Drinking water, including bottled water, can contain small amounts of some contaminants. However the presence of contaminants does not necessarily indicate that water poses a health risk. More information about contaminants and potential health effects can be obtained by calling the USEPAs Safe Drinking Water Hotline at 800-426-4791, or visit their website.

Precautions the Public Should Consider


Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons such as persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HIV / AIDS or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice from their doctors about drinking water directly from the faucet. The United States Environmental Protection Agency / Centers for Disease Control (CDC) guidelines on appropriate means to lessen the risk of infection by cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline at 800-426-4791.

What is in Your Drinking Water


Your drinking water is regularly tested using California Water Resources Control Board Division of Drinking Water (DDW) required methods to ensure its safety. The Consumer Confidence Report, Water Quality Table lists all the constituents detected in your drinking water that have federal and state drinking water standards. Unregulated constituents and other constituents of interest are also included.

About Arsenic in Water


The current maximum contaminant level (MCL) that is allowed in drinking water for arsenic is 10 µg/l (parts per billion or micrograms per liter). The highest level of arsenic was detected at 4 µg/l at one of the City of Monterey Park's wells. Before reaching the distribution system, the water from this well is blended with the water from the other wells that have low or no arsenic in the water. The average arsenic concentration of the blended water delivered to the customers was less than 2 µg/l and 2 µg/l is the detection limit for purposes of reporting.

Some people who drink water containing arsenic in excess of the MCL over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer.