Private Well Water Overview
Private wells draw water from underground reservoirs of water called aquifers. The water is pumped up to the surface by a pump and treated with a simple filter or screen.
There are three types of wells used for drinking water: dug wells, driven wells, and drilled wells. It is important to know which type you own in order to better understand the potential risks and maintenance needs of your home well.
Dug wells are constructed by digging a hole in the ground with a shovel or a backhoe. The well is usually lined with brick, stone, or tile to prevent collapse. Dug wells are the shallowest type of well, typically between 10 and 30 feet deep; therefore, the most likely to become contaminated from nearby agricultural, industrial, or urban sites.
Driven wells are hammered into the ground and draw water from the saturated zone. These types of wells are slightly deeper than dug wells, typically between 30 and 50 feet, and have a moderately high risk of becoming contaminated.
Drilled wells are constructed with a cable tool or a rotary-drilling machine. They are the deepest of the three wells, typically between 100 and 400 feet. A plastic or metal casing is often placed around the well to protect the water from contamination and prevent the well from collapsing. Drilled wells have the lowest risk of contamination, but as with all wells, cannot be assumed to be contamination free.
The United States Environmental Protection Agency’s (USEPA’s) regulations for public drinking water systems do not apply to privately owned wells. However, Michigan does have well construction standards, which if followed should provide safe and reliable water. Some counties have well construction standards more stringent than the state code and all counties require a permit for drilling a well. Contact your local county health department before beginning well construction.
Private wells need to be protected from contamination. It’s good practice to test private wells at least once a year for common water quality indicators and contaminants of concern.