All About Drinking Water
Learn about water sources, treatment processes, and regulations
Where Does Our Drinking Water Come From?
Surface water comes from lakes, rivers, and reservoirs. About 63% of public water systems in the US use surface water as their primary source.
Surface water is more susceptible to contamination from runoff, but is typically treated extensively before distribution.
Groundwater is found in underground aquifers and accessed through wells. About 37% of public water systems use groundwater.
Groundwater is naturally filtered as it percolates through soil and rock layers, but can still be contaminated by industrial activities, agriculture, and improper waste disposal.
The Water Cycle and Drinking Water
All of our drinking water is part of the Earth's water cycle. Water evaporates from oceans, lakes, and rivers, forms clouds, and returns to Earth as precipitation. Some of this water flows into surface water bodies, while some seeps into the ground to replenish aquifers.
Water Sources by Region
Water sources vary significantly by region in the United States:
- Northeast: Primarily surface water from reservoirs and rivers
- Southeast: Mix of surface water and groundwater
- Midwest: Primarily groundwater, with some surface water from the Great Lakes
- Southwest: Heavy reliance on groundwater and imported water
- West Coast: Mix of surface water, groundwater, and imported water