Sources for tap and bottled drinking water 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 Water

• 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.
• 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.
• Radioactive contaminants, which may be naturally-occurring or the result of oil and gas production and mining activities.
• Turbidity (NTU) indicates the presence of suspended matter such as clay, silt, organic particles and microscopic organisms. Not only do particles make water unacceptable to the consumer, they can shield microorganisms from the action of disinfectants.
• Perchlorate In January 2002, the State of California Department of Health Services (DHS) reduced the action level from 18ug/L to the minimum detection level of 4ug/L. Although the DHS does not anticipate adverse health effects when consuming water containing Perchlorate at levels from 4 to 18ug/L, they have reduced the action level to provide for an increase in public health awareness. The basis of the current DHS action is in response to risk assessment studies recently released by the U.S.E.P.A. These studies allege that Perchlorate interferes with the uptake of Iodine by the thyroid gland. Iodine is needed for the production of thyroid hormones, which are required for normal prenatal and postnatal growth and development. Therefore, developing fetuses, infants and children are at risk if their thyroid glands cannot function normally. In adults, thyroid hormones are needed for normal body metabolism.

Limitations on Contaminants

In order to ensure that tap water is safe to drink, the USEPA and California Department of Health Services prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. Department of Health Services regulations also establish limits for contaminants in bottled water that must provide the same protection for public health.

More Information About Contaminants

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 the water possesses a health risk.

More information about contaminants and potential health effects can be obtained by calling the EPA's free Safe Drinking Water Hotline: 1-800-426-4791.

Some people may be more vulnerable to contaminants in drinking water than the general population.

Immuno-compromised persons such as those 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. People at such risk should seek advice about drinking water from their health care providers.

USEPA/Centers for Disease Control (CDC) guidelines on appropriate means to lessen the risk of infection by Cyptosporidium and other microbial contaminants are also available from the free Safe Drinking Water Hotline: 1-800-426-4791.