Using the rotary method, a hole at least three inches larger than the well casing is drilled. The well casing (a rigid pipe that provides a sealed sanitary route to the water-bearing aquifer) is put into place after the well hole is drilled. The annulus (the space between the casing and the earth) is then filled with bentonite slurry (a manufactured clay product) or less commonly with cement. The casing is usually made of PVC plastic pipe, though galvanized steel or black varnished steel casing may also be used.
Cable Tool Method
The cable tool rig drills a hole in the ground that is only slightly larger than the well casing. The well casing is driven into the ground at the same time that the hole is drilled. Plastic casing pipe is not strong enough to withstand the percussion force, so only steel pipe is used. The annulus is sealed with bentonite granules.
Other types of water well construction methods may also be used, though they are very uncommon. Examples include the auger method, hollow rod method, jetting method and driving method. The LCHD suggests contacting several water well contractors to obtain information about the method that would best suit your needs.