Drilled wells are constructed by percussion or rotary-drilling machines. Drilled wells can be thousands of feet deep and require the installation of casing. Drilled wells have a lower risk of contamination due to their depth and use of continuous casing.
1. Well descriptions adapted from the U.S. Geologic Survey, Groundwater Wells (2016)
Well component descriptions adapted from the National Ground Water Association (2017)
Well Location & Construction
Proper well location and construction are key to the safety of your well water. The well should be located so rainwater flows away from it. Rainwater can pick up harmful bacteria and chemicals on the land’s surface. If this water pools near your well, it can seep into it and potentially cause health problems. The Center for Disease Control (CDC) has an excellent web page on well siting.
Appropriate well construction depends on local geologic and groundwater conditions. Your state water-well contractor licensing agency, your local health department, or a local water system professional can provide information on proper well construction. The National Ground Water Association (NGWA) provides a guide for hiring a water system professional that covers key considerations.