Sources of drinking water contamination

Drinking water can become contaminated when germs and chemicals are present in a water sources or water systems in amounts high enough to make people sick. The U.S. Environmental Protection Agency (EPA) sets water quality standards and regulations for Group A public water systems, which are enforced by the state Office of Drinking water.

However, the EPA does not regulate Group B and individual private wells. Group B and private well users are responsible for monitoring their own water quality and keeping it free from contamination. Group B and private wells should pay close attention to potential sources of contamination in their areas.

Potential contamination sources include

• Fertilizers, pesticides, or other chemicals that have been applied to land near the water
• Concentrated animal activities, such as stables, barns, and feeding pens
• Manufacturing operations
• On-site sewage systems
• Sewer overflows
• Flooding
• Storm water
• Wildlife
• Rocks and soil that naturally have chemicals and minerals such as arsenic
• Cracks in water pipes and other problems with the distribution system

Learn more about drinking water contamination in this guidance from Cornell University (PDF) or guidance from the Groundwater Foundation.