Safe Drinking Water
There are many types of pollutants that can contaminate drinking water and cause illness and disease. Regardless of where drinking water comes from - a lake, a river, an underground aquifer, a well, a public water utility, even bottled water - all can be contaminated by a number of impurities.
Some of these contaminants include chemicals like pesticides, heavy metals such as arsenic and lead, human and animal waste, and even chemical by-products created during drinking water treatment. Exposure to these contaminants can cause a number of health problems, ranging from nausea and stomach pain to developmental problems and cancer.
Health Effects of Drinking Water Contamination:
Exposure to microbes in water can lead to nausea, fevers, diarrhea and dehydration. Long-term exposure can cause rashes, heart disease, diabetes, cancer, and a number of immune, neurological, developmental, and reproductive problems.
Because of the different types and levels of pollutants in U.S. waters, it is very difficult to observe accurately the rate of disease from contamination in water. However, it has been estimated that approximately 900,000 people fall ill and as many as 900 die each year from waterborne infectious disease. It is equally difficult to measure the adverse health impact of waterborne chemicals because of the long lag between exposure and symptoms, the multiple ways chemicals can enter the body, and the mobility of populations.
While everyone is at risk for health problems because of drinking water contamination, the level of risk varies from person to person and depends on a number of factors. These include: the specific contaminant(s) to which an individual is exposed; the size of the dose; demographic characteristics; pre-existing health conditions; lifestyle choices including smoking and diet; and the effects of exposure to multiple chemicals. Pregnant women are particularly susceptible to exposure, as are infants and children, the elderly, and persons with weakened immune systems.
To educate health professionals and the public about drinking water and disease, PSR published a primer and series of fact sheets called Drinking Water and Disease: What Health Care Providers Should Know. The primer and series address the problems associated with contaminated drinking water and offer recommended actions that health care providers can take to protect communities from water contamination.
Chemical and Microbial Contaminants:
There are many kinds of microbes and chemical toxicants that can contaminate drinking water and threaten public health. The most common microbial contaminants include E. coli, Cryptosporidium, Giardia and Salmonella, while common chemical contaminants include arsenic, radon, lead and nitrates. Some of these contaminants are naturally occurring, while others are man-made.
Contamination of drinking water can occur in several ways. A region's industrial and agricultural practices, geological make up, and weather patterns often determines which contaminants make their way into source water, which is the body of surface or ground water from which drinking water supplies are derived. Contamination problems also can arise during the water utilities' treatment and distribution processes that filter water and then deliver it to residential homes. Treatment processes are sometimes ineffective and the chemicals used to remove certain contaminants can create chemical by-products that pose a threat to human health. Lead and other forms of pipes that are found in some distribution systems, as well as in residential houses, can also leach into drinking water, causing local contamination.
The U.S. Environmental Protection Agency (EPA) sets maximum contamination levels (MCLs) for various substances in drinking water. States that have approved water quality programs have the authority to pass their own standards, which must be equal to or stricter than the federal levels. However, only the drinking water supplied by public water systems is protected. Bottled water and drinking water from private wells are not fully regulated.
The two types of source water are surface water (rivers, streams, and lakes) and ground water, which comes primarily from underground aquifers. The geography of a particular US region is normally the primary determinant for which water sources supply households with drinking water.
Source water is constantly under threat from environmental contamination, making it an important drinking water and land use planning concern. While ground water can become polluted by "naturally occurring" contaminants and sometimes by human-made contaminants, surface water is particularly at risk. "Naturally occurring" contamination includes contaminants from animal fecal matter, algal growth, or geologic formations. Surface water also is vulnerable to human-made contamination, both from point sources (such as pipes or man-made ditches that discharge pollutants into water bodies) and non-point sources (such as run-off from streets and farmland). While the Clean Water Act has reduced point source contamination, non-point sources are still a considerable threat to the health of waterways.
Although source water protection does not solve all drinking water contamination problems, it can play a crucial role in eliminating contamination before it starts.