Your well is a direct connection between you and your water supply. Contaminants can flow down your well as easily as water flows up it. The farther away from your well you are, the more sand, gravel and clay there is to filter out contaminants before they reach your water supply. For most well owners, groundwater is their only source of water and should, therefore, be protected. Groundwater moves very slowly, often only a few feet per year, and because it moves so slowly, once it becomes polluted, it takes years for it to be naturally flushed clean. Manually cleaning pollutants out of groundwater can be extremely costly and difficult. Often, the only solution is to find a new source of water.
The protective well radius is a uniform circle around the well, which establishes a setback distance from property lines and septic systems, and has a radius of 75 feet for design flows up to 750 gallons per day which is equivalent to a five-bedroom home.
For new wells, the protective area is required to be maintained wholly within the property boundaries of the lot to be served by the well. However, protective well radii may overlap onto other lands such as: land that is protected by a recorded easement, land that is permanently dedicated to a use that precludes development, or on land within a municipal property line septic system setback.
Examples of lands that are precluded from development include: wetlands, surface waters, roads, and protected conservation lands where the deed precludes development of buildings or subsurface waste disposal systems within the affected area. Municipal property line septic system setbacks are minimum setback distances from septic systems to property lines established by local ordinance. Many towns have setback criteria that differ from the 10-foot requirement. These setback distances may vary from town to town.
Another good tip is to create a circle at least 50 feet in diameter around your well where you don't store, mix, spray, spill, bury or dump anything that you don't want to drink. Don't forget to look out for your neighbor's well if it is near your property line. Any contamination in your neighbor's well can travel into your well. Some activities legally require more than a 50-foot zone of protection.
As a general guidance, personal drinking water wells should have a minimum horizontal distance of at least 10 feet and preferably 25 feet from such boundaries. State or local standards may be less or more stringent in your area. Contact your local health department for more information in your area.