Minimum well clearance distance from holding tank?

• A. 50 feet
• B. 10 feet
• C. 75 feet
• D. 25 feet

Answer: (D)

Maintaining a safe distance between a drinking water well and a holding tank is about preventing contamination of the well by waste liquids. A holding tank can release waste if it leaks or overflows, and contaminants can travel through soil or groundwater toward the well. The minimum setback recognizes that risk and sets a practical boundary to reduce it.

In this context, the standard minimum distance is 25 feet. This distance provides a balance between protecting the water supply and allowing feasible tank placement, assuming the tank is properly sealed, vented, and maintained, and the soil conditions aren’t unusually favorable to rapid contaminant movement. If soil conditions are poor (high groundwater, permeable soils, or nearby surface water) or the well is shallow, the required distance would typically be larger.