Drilling a water well can be relatively easy or quite difficult and complex, depending on the circumstances. The main factors to consider are the depth of the water table and the types of soil and bedrock to be drilled through. Current soil conditions, weather and available equipment also need to be taken into account. The basic process of drilling a well involves boring through soil and bedrock with a drill bit while the broken pieces are flushed up to the surface in a drilling fluid (or drilling mud). When you reach the water table, the well is cased, piping is inserted down to the water table, a pump is installed, and the well is complete.
Determine the Best Location to Drill a Well
Determine the best location to drill a well. Locate your water table and identify the local soil and subsurface conditions. Many states now have excellent online resources with information about existing wells, and USGS geographic and topographic maps will also provide useful information about the water table and subsurface conditions. Talking to your neighbors with wells is also a very good way to get firsthand information about drilling a well in your area.
Rent a Drill
Rent a drill. Unless you have extremely hard or rocky subsurface conditions, rotary drilling is probably going to be the most effective and economical method to drill the well. Rotary drilling involves a drill bit made of a very hard metal like tungsten or carborundum grinding up the rocks and soil to drill the hole. Drilling fluid is also pumped into the drill pipe to act as a coolant and to flush the ground up dirt and rocks (cuttings) to the surface.
If you do have to deal with very rocky conditions it is probably best to use the down-hole air hammer drilling method where compressed air is used to break up the rocks and force the broken chips up to the surface.
Drill the Well
Drill the well until you reach the water table. The water table can be as little as 20 feet down to as much as 500 feet or more in extreme cases. You will want to drill down several feet after you hit the water table to create some space for the water to accumulate.
Install the Casing
Install the casing for the well. The well casing is usually made of steel or plastic and usually at least the top 20 feet of a well are cased. Make sure to fill in the space between the casing and the drilled hole with cement or bentonite grout to prevent polluted ground water from seeping into the aquifer.
Lay piping for the well. Copper or plastic piping is generally preferred for underground installation, but galvanized steel can be used if the water is not highly mineralized. Be sure the piping is large enough to allow enough water to flow to meet the expected demand for the well. Make sure the intake pipe is at least 12 inches below the water table, as the level will fluctuate.
Install a Pump
Install a pump for the well. Calculate the size (hp) of the pump you will need based on your expected peak water demand. It is best to use a pump with at least 20 percent greater capacity than that just to be on the safe side.