Pesticides that have the greatest potential to leach to ground water are highly water soluble, relatively persistent and do not adsorb to soil. The Cooperative Extension Service and the Natural Resources Conservation Service can assist you in selecting the appropriate pesticide. Pesticide contamination of ground water frequently is associated with pesticide handling practices in the vicinity of wells. Pesticide spills near wells can move directly and quickly into ground water. Wells should be properly cased, capped, and grouted.
Unprotected wells act as conduits for surface contaminants to the aquifer.
Open wells near mixing-loading sites are particularly vulnerable to contamination. Slope the grade around the wellhead to direct runoff away from the well. Close abandoned wells and never dispose of wastes in unused wells. Avoid mixing, storing, or disposing of pesticides within 100 feet of a well. Some pesticide labels may recommend greater distances.