What Contaminates Are in Water

Water Source
The sources of drinking water generally include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or 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, may reasonably be expected to contain at least small amounts of some contaminants. 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 about drinking water from their health care providers. 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 DHS approved methods to ensure its safety. The 2005 Consumer Confidence Report, Water Quality Tablelists all the constituents detected in your drinking water that have federal and state drinking water standards. Detected unregulated constituents and other constituents of interest are also included.

About Arsenic in Water
The current maximum contaminant level (MCL) for arsenic is 50 ug/l (parts per billion or micrograms per liter). The highest level of arsenic was detected at 38 ug/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 9 ug/l, which is below the current MCL of 50 ug/l and is also below the revised federal arsenic standard of 10 ug/l which is effective on January 23, 2006.

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.