Q: I’m building new house with a basement, and drilling a deep water well. How far should the wellhead be from the foundation and septic system? — Brad
A: Well clearances are typically governed by state and municipal law, which varies a bit from state to state and town to town. Your local health department or building department can provide you with details.
The minimum distance from a driven or drilled well to a residential structure is typically 5 to 10 feet measured to the farthest building projection. This is usually the roof overhang.
Since water wells are replenished from surface water that seeps through the ground into the aquifer, the main concern is contamination from surface runoff, septic systems, farming, and other activities. It’s best to locate the well uphill and as far as possible from sources of pollution.
Also, make sure you slope the soil away from the wellhead to keep surface contaminants away from the well casing.
The Centers for Disease Control (CDC) makes these recommendations for minimum clearances to a water well:
50 feet: Septic Tanks
50 feet: Livestock yards, Silos, Septic Leach Fields
100 feet: Petroleum Tanks, Liquid-Tight Manure Storage and Fertilizer Storage and Handling
250 feet: Manure stacks
Wells should also be a safe distance from sewer and septic lines, culverts and drainage ditches, swimming pools, salt storage areas, landfills, and any other sources of contamination.