The U.S. Environmental Protection Agency (EPA) regulates drinking water quality in public water systems and sets limits for germs and chemicals in water. Sometimes, however, unsafe levels of harmful germs and chemicals contaminate our public drinking water. The germs and chemicals can get into the water at its source however, for example the ground water, water from lakes, or rivers, or during the traveling of water through the distribution system, after the water treatment plant has already removed germs and chemicals from source water.
The people who are more vulnerable to getting sick from the germs and chemicals in the water are infants, young children, women who are pregnant, older adults, and those who have a weakened immune system. Germs and chemicals can get in drinking wter at the water’s source or in the distribution system even after the water has already been treated.
The harmful germs and chemicals can get in the water from many sources. Some of these sources are from fertilizers, pesticides, or other chemicals that have been applied to land near the water, concentrated feeding operations (large industrial animal farms), manufacturing operations, sewer overflows, storm water, wildlife, rocks and soil that naturally have chemicals and minerals such as arsenic, radon, and uranium, and cracks in water pipes or other problem sin the distribution system.
Global Environmental Change 