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Penn State: Private Well Construction, Maintenance
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Proper well siting and construction leads to better water quality. Tips for inspecting older wells such as looking for signs of casing failure, the use of grout and the value of a sealed cap are discussed. A worksheet to help evaluate the condition and construction of an older well is discussed and linked.
If you are not on a public water supply, you probably get your water from a well. If you use private water supplies, such as wells, springs or cisterns, then the responsibility for the quality of your water is your own.
You must take steps to ensure that your water is safe to drink. It must be free of pathogenic bacteria, viruses, and harmful chemical impurities. It should also be clean, clear, and nonstaining, without offensive odors. A water test can confirm the presence of contaminants in a private water supply.
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 contamination sources 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 heavier 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 above 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” can be used to rank your drinking water well conditions and management practices to see how they might affect groundwater quality.
For additional information on wells, visit the Penn State Extension Water Resources webpage and find out what to do before drilling a well, how to drill a well, how to use your well, and how to fix your well.
Also available is the publication, "Recommendations for Construction of Private Water Wells in Bedrock," from the DCNR Bureau of Topographic and Geologic Survey.
(Article prepared by George Hurd, Senior Extension Educator, Penn State Extension - Franklin County, and reprinted from Penn State Extension Watershed Winds online newsletter.)
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1/30/2012 |
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