The majority of rural Americans and many in small communities obtain drinking water from private wells. According to the Environmental Protection Agency in Drinking Water From Household Wells, about 15 percent of Americans have their own sources of drinking water such as wells, cisterns, and springs. These folks are responsible for maintaining a safe water supply. Private wells provide a reliable, safe source of drinking water when the well is properly located, constructed and maintained.
Well water is drawn from the groundwater. Groundwater is found beneath the land surface in pores and cracks in the bedrock and sand or gravel.
Private Wells May be Dug, Driven or Drilled
A well is a hole in the ground, held open by a pipe (casing) that extends to an aquifer in the groundwater. A pump draws water and sends it to the plumbing system. There are three types of private drinking water wells: dug, driven, and drilled.
Dug wells are holes dug by shovel or backhoe, lined with stones or tile to prevent collapse and covered with wood, stone, or concrete. Most dug wells are 10 to 30 feet deep. Dug wells have the highest risk of becoming contaminated since they are so shallow and open.
Driven or sand-point wells are typically up to 50 feet deep and are usually found in areas with deep sand and gravel deposits. Driven wells are relatively shallow and have a moderate-to-high risk of contamination from nearby land activities.
Drilled wells are forced anywhere from 100-400 feet into the bedrock, until a viable source of water is located. These deep wells provide a good source of safe drinking water.
Driven and drilled wells have casings to prevent collapse of the walls and prevent contaminants from entering. The casing also contains the pump and pipe that moves water to the surface.
A pressure tank brings the water to the home plumbing system and stores some water for immediate use, the pump supplies the pressure tank.
Well Contamination Sources
Contamination can come from several sources. Perhaps the largest concern is the septic system. A failed septic system, or a system located too close to a well can cause contamination. Other sources of well contamination are fertilizers and pesticides applied to lawns, gardens and crops close to the well; livestock allowed in the area of the wellhead can also cause problems.
Testing Private Well Water
If tap water looks good, tastes good and smells good, it must be safe, right? Not necessarily! Many contaminants have no odor, color or taste. Water that looks, smells or tastes bad may be safe. There are a few basic guidelines to evaluate drinking water, but these are only indicators. Private wells that are less than 50 feet deep or are older than 40 years should be tested annually. Shallow wells may be more easily contaminated and older well casings may no longer be watertight. The Minnesota Dept. of Health recommends testing wells every 2—3 years for coliform bacteria and nitrates.
Tips for Private Well Maintenance
- Use licensed or certified water well drillers and service providers for well installation or service.
- Provide well maintenance every 1 – 3 years, including a bacteria test. Drinking water should be checked if there is a change in taste, odor or appearance, or if the system is serviced. Check local yellow pages for certified laboratories that test drinking water supplies or ask the local public health department.
- At times, most private wells need to be chlorinated to manage bacteria or other issues. Be sure to follow safe chlorination guidelines that protect drinking water and the septic system.
- Keep hazardous chemicals including paint, fertilizer, pesticides, and motor oil away from the well.
- Periodically check the well cap to ensure it is in good repair. Ensure it is not damaged by lawn mowers or other equipment. The well casing and well cap should be at least one foot above ground, preventing the well from being flooded and keeping it from being exposed to things like lawn chemicals.
- Many driven wellheads and pumps are located in the home's basement. Ensure the area is protected from flooding or other forms of contamination.
- Keep well the necessary setbacks from buildings and the septic system; see local codes for information.
- When mixing pesticides, fertilizers or other chemicals, do not put the hose inside the container to avoid back-siphoning contamination.
- Keep well records in a safe place, including construction report, maintenance and water testing results.
- If a new well is necessary, ensure the old well is properly sealed and abandoned.
Considering a Water Treatment Device?
Read information on how to select an appropriate device or service.
Private Wells Provide Good, Safe Drinking Water
Those with private wells appreciate the taste of the water - few things compare to a cold glass of well water. Caring for drinking water wells properly will ensure a safe supply of water.
Valerie Prax - Valerie Prax recently retired after nearly 35 years with University of Minnesota Extension. She served as an Educator and Professor for 27 ...
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