Learn about these common water contaminants that can lead to unsafe drinking water.
Common Water Contaminants
One of the most commonly occurring inorganic contaminants, lead typically finds its way into drinking water from sources inside the home. Until their ban in 1991, lead pipes and solder commonly were used in home plumbing systems. If your home was built before the ban and the water pipes have not been replaced, it's likely that lead could be dissolving into your drinking water. Lead is particularly dangerous for young children, and has been associated with behavioral disorders, brain damage and lowered IQ. In adults, long-term exposure has been linked to strokes, cancer and elevated blood pressure.
Lead tends to accumulate as water sits in pipes overnight. You can decrease the risk of lead exposure by simply allowing water to run through faucets for a couple of minutes each morning, before filling any drinking containers. A simple blood test, taken annually, will tell if you are consuming too much lead from water or other sources.
Although nitrates occur naturally, high levels often are a problem in farming areas or in places where there is a high concentration of septic systems. Wastewater, fertilizers and fecal matter, from humans and other animals, all can be sources of nitrates. Although adults can tolerate high levels reasonably well, nitrates can be very dangerous for infants, reducing their blood's ability to carry oxygen and causing methemoglobinemia, or blue-baby syndrome.
Pesticides, particularly popular weed killers such as atrazine, have been found in nearly every stream tested in the United States. Atrazine and other herbicides, such as 2,4-D, are commonly found in groundwater. Federal drinking-water laws allow minute quantities of pesticides in municipal water. Debate continues about the possible health effects of these legal amounts of pesticides in our drinking water.
Arsenic finds its way into water supplies from both natural sources and human activities. In some places, particularly the Southwest, arsenic leaches into the water from certain types of rock. Gas- and oil-well drilling and gold mining are other sources of arsenic contamination. Although prolonged exposure to arsenic has been shown to cause several forms of cancer, until recently just how much of it poses a human health risk has been a source of heated debate. Bowing to new scientific evidence and public pressure, the federal government has finally agreed to lower the acceptable amount from 50 parts per billion (ppb) to 10 ppb, beginning January 2006. Chronic exposure to low levels of arsenic can cause cancer, skin lesions, circulatory problems and nervous-system disorders.
In water supplies, copper, iron and manganese pose more of a nuisance than a health threat. (These three minerals are essential trace nutrients in our bodies, but they must be consumed in amounts that do not exceed a toxic threshold.)
Iron often imparts a metallic taste and leaves telltale orange-brown stains on clothes and linens. Manganese behaves similarly, affecting taste and producing blackish stains. Copper usually originates from highly acidic water, which corrodes copper plumbing. Besides its metallic taste, in high concentrations, copper can cause stomach cramps and intestinal illness. You'll find its signature blue-green stains in sinks and bathtubs.