Please examine the well diagram on this web site showing how we construct our wells. Grouting is the process by which the space between the borehole and the well casing is sealed to prevent contaminants from the surface and upper water table seeping down into the lower water supply for the well, wherever wells are drilled. When a well is constructed in our area of work in New Jersey, an oversized borehole is drilled to accommodate placement of the well casing and well screen. Unlike wells drilled into rock (consolidated formations) in the northern section of the state above the Raritan River, a well screen is needed in our drilling areas that consist of sands, silts and clays (unconsolidated formations). After placement in the borehole, the outside of the well screen is packed with specially sized sand (called gravel pack) that allows water to enter the well, but keeps out small sand and silt particles present in the aquifer. The space above the gravel pack is sealed (grouted) by pumping under pressure either a viscous bentonite clay or cement to prevent downward migration of contaminants. Proper grouting is essential in order to protect your water supply and quite possibly, your neighbor’s water supply, too.