Ground water sources must be located at what distance from potential sources of contamination?

• A. 50 feet.
• B. 100 feet.
• C. 50 yards.
• D. 100 yards.

Answer: (D)

The main idea here is protecting groundwater by keeping wells at a safe distance from anything that could contaminate the surface and migrate downward with water. Contaminants from surface sources—like septic systems, storage tanks, agricultural activities, or chemical spills—can move through soil and groundwater. The farther the source is from the well, the lower the chance that a contaminant plume will reach the drinking water before it’s diluted, filtered by soil, or attenuated by natural processes. A distance of 100 yards provides a generous buffer that works across a range of soils, depths to groundwater, and aquifer conditions, helping to reduce risk even when conditions aren’t ideal. Shorter distances may be acceptable in some specific, well-characterized settings, but they leave less margin for error given the variability in real-world hydrogeology.