Private Well Maintenance
Posted: January 24, 2012
Old or poorly designed wells increase the risk of groundwater contamination by allowing rain or snowmelt to reach the water table without being filtered through soil. If a well is located in a depression or pit, or is not properly sealed and capped, surface water carrying nitrates, bacteria, pesticides, and other pollutants may flow directly into your drinking water.
You wouldn't let a car go too long without a tune-up or oil change. Your well deserves the same attention. Good maintenance means keeping the well area clean and accessible, keeping pollutants as far away as possible, and periodically having a qualified well driller or pump installer check the well when problems are suspected. By eliminating the contamination and properly maintaining your well, you are helping protect your own drinking water and water resources in your community.
According to the National Farm*A*Syst and Home*A*Syst Program, well age is an important factor in predicting the likelihood of contamination. Wells constructed more than 70 years ago are likely to be shallow and poorly constructed. Older well pumps are more likely to leak lubricating oils, which can get into the water. Older wells are also more likely to have thinner casings which may be cracked or corroded. Even wells with modern casings that are 30 to 40 years old are subject to corrosion and perforation. If you have an older well, you may want to have it inspected by a qualified well driller.
Well drillers install a steel or plastic pipe "casing" to prevent collapse of the hole during drilling. The space between the casing and sides of the hole offers a direct channel for surface water - and pollutants - to reach the water table. To seal off that channel, drillers fill the space with grout (cement or a special type of clay called bentonite). You should visually inspect the condition of your well casing for holes or cracks. Examine the part that extends from the ground as well as inside the casing, using a flashlight. If you can move the casing around by pushing it, you may have a problem with your well casing's ability to keep out contaminants. Sometimes, damaged casings can be detected by listening for water running down into the well when the pump is not running. If you hear water, there might be a crack or hole in the casing or your casing may not reach down to the water table. Either situation is risky.
The well cap should be firmly attached to the casing, with a screened vent allowing only air to enter. Wiring for the pump should be secured in an electric conduit pipe. If your well has vent, be sure that it faces the ground, is tightly connected to the well cap or seal, and is properly screened to keep insects out.
As rain and surface water soak into the soil, they may carry pollutants down to the water table. In some places, this process happens quickly - in weeks, days, or even hours. Local geologic conditions determine how long this takes. Shallow wells, which draw from groundwater nearest the land surface, are most likely to be affected by local sources of contamination.
In addition to water analysis test results, you should keep well construction details, as well as the dates and results of maintenance visits for the well and pump. It is important to keep good records so you and future owners can follow a good maintenance schedule.
A Farm*A*Syst worksheet titled, “Water Well Condition and Construction” is available for free at: http://cropsoil.psu.edu/extension/farm-a-syst/pubs/uc137.pdf. Through using this worksheet, you can rank your drinking water well conditions and management practices according to how they might affect groundwater. For additional information on wells, visit the following Penn State Extension Water Resources webpage: http://extension.psu.edu/water/drinking-water/contstruction. Information on what to do before drilling a well, how to drill a well, how to use your well, and how to fix your well is available through publications you can download from this webpage.
George Hurd is the Penn State Cooperative Extension Environmental/Resource Development Educator serving Cumberland County. Penn State Extension in Cumberland County is located at 310 Allen Road, Suite 601, Carlisle, PA 17013,. Phone 717-240-6500 or e-mail CumberlandExt@psu.edu.
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