Water Quality by State

Tap water quality in the United States varies significantly from state to state. Some states consistently meet or exceed EPA standards, while others face ongoing challenges with contaminants, aging infrastructure, and regulatory enforcement. Understanding how your state compares can help you make informed decisions about your drinking water.

Several key factors determine the quality of tap water in any given state. Infrastructure age plays a major role; states with older water systems are more likely to have lead pipes, corroding distribution networks, and treatment facilities that struggle to keep up with modern contaminant standards. Cities like Flint, Michigan demonstrated how aging infrastructure can create serious public health crises.

Agricultural runoff is another significant factor. States with large farming operations often see elevated levels of nitrates, pesticides, and herbicides in their water supply. The Midwest and Great Plains states are particularly affected, where fertilizer and animal waste can seep into groundwater and surface water sources used for drinking water.

Industrial pollution, both historical and ongoing, affects water quality in many states. PFAS contamination from military bases, manufacturing facilities, and firefighting foam has been detected in water systems across the country. States with heavy industrial histories, such as New Jersey, Michigan, and North Carolina, often face elevated levels of these persistent chemicals.

Natural geology also shapes water quality. Arsenic occurs naturally in groundwater across the Southwest and parts of New England. Radon, uranium, and other naturally occurring contaminants vary by region based on the underlying rock and soil composition.

Check your specific water quality

While state-level data provides useful context, water quality can vary dramatically between cities, counties, and even neighbourhoods within the same state. The best way to understand what is in your tap water is to look up your ZIP code for a personalised water quality report based on your specific water system.