These range from E. coli to nitrates to arsenic to various microscopic organisms. These can cause severe intestinal infections that can be fatal. Inorganic contaminants such as lead, arsenic and nitrates in excessive levels have caused serious illness and death in infants. Chlorine that is used to kill bacteria in water is also an inorganic contaminant. Such organic compounds as pesticides and herbicides have been found in the water of more than 50 million Americans and are linked to circulatory, respiratory and nerve disorders.
Radioactive contaminants round out the list with such elements as radium and uranium.
The National Resource Defense Council reported that over 50 million Americans drink water containing radium and uranium. Over 20 years ago, Congress passed the original Safe Drinking Water Act. Since then the Environmental Protection Agency has set uniform nationwide minimum standards. The EPA uses statistics and risk assessment to deal with potential contamination. First, drinking water quality standards are established.