A sanitary well cap with a rubber seal is one way to help protect your groundwater. (Photo by Jennifer Fetter, Penn State)
If you have a private well as your water source, it is tapped directly into water-rich layers of rock to provide water for your home and family. Wells can range from very shallow - maybe only 40 feet deep - to very deep – perhaps 200 feet or more underground. One misconception about wells, is that they are immune to contamination because they are so deep, or that any contaminants will be filtered out by the soil and rock layers above before reaching your water source. While some amount of filtering may be taking place, well owners still must take steps to protect these groundwater resources. When a well is drilled, that well becomes a direct line into the groundwater aquifer. When that well is pumped, it pulls in water from all of the surrounding water-rich rocks in the shape of a cone or funnel. This means that water is being drawn in from more than just the immediate area right around the well casing.
Because all of this cone-shaped area needs to be taken into consideration, this 100 foot radius immediately around your wellhead is your wellhead protection area. This boundary represents an area that contamination will have the greatest potential to impact your water supply. Be extra careful in this area, especially with things that are put on the ground. Pesticides, fertilizers, pet and animal waste, septic system drain fields, dump sites, compost piles – all these things should be excluded from the well head protection area. The ground around your well casing should be sloped away from the wellhead too, to keep surface water from running down along the casing and into your water supply.
Even the well cap that is on your water well should be taken into consideration. A standard well cap, found on most wells, is a metal cap that is bolted onto the top of the well casing and leaves a gap between the casing and the cap itself. This gap can allow for surface water, insects, or rodents to enter the well and contaminate your water supply. A better alternative is to use a sanitary or vermin-proof well cap. This type of cap has a rubber gasket that creates a tight seal with the well casing, and eliminates the gap where contamination can enter. A sanitary cap can be purchased from and installed by your well driller. Wells should be inspected every few years by a well professional and annually by the homeowner to be sure there are no visible cracks to the casing, damage to the well cap, or other well structures.
For more information on maintaining your well visit Water Well Maintenance and Rehabilitation.