How is a Domestic or Residential Well Constructed?
A domestic well, or a residential well, supplies non-transient populations with water for household purposes. Common non-transient water systems include residences, schools, and businesses. If you live outside of an urban area, or you are not connected to a community water system, then you will need to access groundwater for your water supply.
Wells meant for domestic or residential use must be designed to protect water from contaminates, bacteria and ground particles. Typically a cable tool or rotary-drilling machine is used to create the well. A drill hole will pass through layers of the earth to an aquifer, or underground reservoir of groundwater. If drilling occurs on unconsolidated formations, like sand or gravel, then it is required that a casing and screen are installed. The underlying geology (bedrock, sand or gravel) will slightly change the materials used in construction. Professionally trained and licensed drillers will analyze the drill cuttings to determine the appropriate placement as well as screen size. The annular space between the water well casing and borehole must then be pressure grouted in place to provide a watertight seal against surface contaminants entering the well.
A water well casing, an Illinois approved well cap or seal, extending a minimum of 8 inches above finished surface grade is applied to keep surface water and other drainage out of the water well. The cap is water tight, vermin proof, vented and removable only with tools.
Some common characteristics of domestic wells are:
- 4 to 6 inches in diameter to complement most pumps made for residential and domestic use.
- 125 – 300 feet deep ( but can be as much as 1000 ft )
- The use of rotary or cable tool are the most common drilling methods.
- The full depth of the borehole is cased with PVC or steel.
- A well screen is used to allows water to pass through while holding back sand and gravel particles in the aquifer.
Drilled water wells are the most common form of water well construction in Illinois. Illinois enjoys a generous supply of groundwater, although it is not always evenly distributed. Depth to aquifers will vary. Interestingly, variation can occur at distances of a few feet. Illinois is fortunate to have an abundance of geological information on file at the State Water Survey and the State Geological Survey. This data comes from water well construction logs submitted by the water well construction, records to back before 1890.
Read more common questions asked about wells, pumps and well water services.