In order to understand how a well is drilled, let us explain a little bit about about ground water. Ground water is water that is below the earth surface. It originally is rain or snow that seeps into the ground and collects. As this water seeps into the ground it settles in the cracks or pores of underground rock and spaces between sand and gravel.
In time it trickles into a layer of rock or other material that is water tight. This zone is known as an aquifer. Aquifers are usually made of rock, gravel, limestone or sandstone. The water in the Earth that is drilled into is known as the water table.
A well is made by finding a water table. It is basically a hole drilled into an aquifer. Wells come in different shapes and sizes so when contracting for a well, remember that is more than just drilling the hole.
All private well construction is based on establishing the right location for the well, sizing the system correctly and choosing the right well drilling techniques. Contracting the right well drilling company is paramount because a well seasoned contractor is familiar with the hydrology in that area and also the state and local codes that must be adhered to.
When drilling a well it must be lined with casing to keep the soil from collapsing into the borehole and to keep an unobstructed conduit for the water to be brought to the surface. Casing can either be steel or plastic (PVC) pipe. This pipe must be strong enough to withstand being driven down the borehole. It also must be strong enough and also to withstand the stress on the pipe due to the depth of the well. The lower the well the more stress factor is involved.
What the well produces is expressed in gallons per minutes (gpm). During testing, the driller will document how many gpm were withdrawn during the test, how far the water level dropped and how long it took to cover.