Here is some information about the health risks associated with contaminants that may be found in drinking water. Remember, your drinking water must meet very strict health and safety standards for more than 100 contaminants, including many of those listed below.

Arsenic
Arsenic is a naturally occurring element found in rocks, soil, water and air. It is used as a wood preservative as well as in certain agricultural applications, semi-conductors, paints, dyes and soaps. Arsenic can get into the water from the natural erosion of rocks, from the runoff of agricultural fields and discharges from industrial processes. Arsenic is also found in many of the foods we eat. Long-term exposure to elevated levels of arsenic in drinking water have been linked to certain cancers (e.g., bladder, skin, lung) as well as hypertension, diabetes, deficits in the IQ of children and other diseases.

In Feb. 2003, the EPA established a new arsenic standard which was substantially lower than the existing standard.

Cryptosporidium
Cryptosporidium is a parasite that lives in the intestines of humans, farm animals, wild animals and household pets. It can be found in lakes, rivers, streams and other sources, and comes from contaminated animal or human feces. If a live organism is swallowed, an intestinal infection can start causing an illness called "cryptosporidiosis." Symptoms last one to two weeks and include diarrhea, headache, nausea and fever. Healthy people recover on their own, but those with already weak immune systems face long-lasting, even life-threatening symptoms.

Lead
Lead is a naturally occurring metal that can be found in household plumbing, fixtures, and solder and/or in the connectors in the water lines that bring water from the main lines to your home. Exposure to lead from water can occur when lead plumbing materials and fixtures get worn down and corroded. Since most contamination from corrosion occurs in household lead pipes, retail water suppliers are required to take water samples from household taps. If lead levels in the samples exceed regulatory requirements, the water supplier will increase steps to control corrosion.

Infants and children who drink water containing excessive levels of lead could experience delays in their physical or mental development. In children, their attention spans and learning abilities can be affected. Adults who drink water high in lead content over many years could develop kidney problems or high blood pressure.

The most common source of exposure to lead for children is from deteriorating or peeling lead-based paint and dust or residential soil contaminated with lead. Although the residential use of lead-based paints was banned by the federal Consumer Product Safety Commission in 1978, these paints are still found in many older homes.

MTBE (methyl tertiary butylether)
US Environmental Protection Agency
MTBE is a member of a group of chemicals known as fuel oxygenates. It is added to gasoline to reduce carbon monoxide and ozone levels caused by auto emission--a primary source of air pollution. Gasoline sold in areas that do not meet certain air quality standards frequently contains MTBE. MTBE can get into groundwater supplies primarily from leaking underground gasoline storage tanks. It can also get into lakes and reservoirs from the emissions of certain recreational watercraft.

MTBE is being phased out in California over the next several years because it has been found in a number of surface and groundwater supplies. While the levels detected have generally been well below levels considered a possible risk to human health, the compound produces an unpleasant taste and odor, even at low concentrations. California recently adopted a secondary standard for MTBE.

Nitrates
Nitrates are compounds containing nitrogen and oxygen. They can be found in water supplies as a result of runoff from animal waste, fertilizers, leaching from septic tanks and erosion of natural deposits. Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill or face a life-threatning illness if there isn't immediate medical attention. Symptoms include shortness of breath and blueness of the skin due to interference from nitrates in the blood's ability to carry oxygen.

Perchlorate
Perchlorate originates as a contaminant in groundwater and surface waters when the salts of ammonium, potassium, magnesium, or sodium dissolve in water. One major source of contamination is the manufacture or improper disposal of ammonium perchlorate, which is the primary ingredient for solid rocket fuel and is a fundamental component in munitions and fireworks.

Perchlorate interferes with hormone production by blocking the uptake of iodide into the thyroid gland. Iodide is essential for thyroid hormone production. Thyroid hormones regulate metabolism in adults and development and metabolism in children. Impaired thyroid function in pregnant women can cause damage to the fetus and newborn, resulting in adverse effects on behavior, development and learning.

Research into different treatments is still being evaluated. Conventional water treatment does not effectively remove perchlorate. For more information, please click here.

THMs
THMs (total trihalomethanes) are disinfection byproducts that form when naturally occurring organic materials in water combine with chlorine used to treat water. Animal studies have shown that some disinfection byproducts, at very high doses and over an extended period of time, are suspected of causing cancer. THMs also have been linked to miscarriages and other adverse birth outcomes.