“…While presence of fecal bacteria was much less common in deeper wells, some wells as deep as 250 ft (80 m) were positive. Increased levels of bacterial contamination of drinking well water after periods of rain have been noted in several studies [23][24][25]45]. In one study, it was noted that while an increase in coliform bacteria appears almost immediately after periods of heavy rainfall in shallow wells, in deeper wells the increase did not occur until 2 weeks later [46].…”