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Some ground water occurs at the surface as springs, but in most cases, a water well is needed to reach the aquifer where ground water is found. Today, most wells are made by drilling into the rock layers using drilling machines (rigs) to access water deep beneath the surface. In most cases electric pumps are used to raise the water to the surface. The creation of a water well (a specially engineered hole in the ground) consists of several elements. After selecting the site to drill the well, (local codes and set-back requirements may limit choice!), the process usually includes drilling, development, testing and equipment installation. Drilling The actual hole for most home wells is usually drilled at a diameter of between six to twelve inches. The drilling method that the contractor decides as most appropriate will depend on the geologic formations, the required water yield and the type of drilling equipment available.
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Well Development The drilling process often uses specially
formulated drilling mud to help carry the drilled pieces to the surface. Most
drilling also creates finely ground rock material. All fine particles need to be
removed from a well in order that it may efficiently produce water. The process
of removing fine particles is called well development. Drillers usually do this
by using compressed air or a bailer to agitate and remove water in the well
until it runs clear. Yield Tests For most home wells it is not necessary to undertake extensive testing. Experienced drillers will have a good idea of the well's performance from the drilling and development process. The yield potential is important for selecting the right pump and for advising the well owner about maximum yield. It is very important to know the well's limitations. Ideally, water will flow into the well at the same rate that it is removed by the pump. There are three important pieces of information needed for designing an efficient water system: the static water level, the water level after pumping a known volume of water and the time it takes for the well water level to recover after pumping stops. For low yield wells a long term well test of eight hours or more is recommended. Low-Yield Wells In some areas of The United States, wells are not capable of producing the amount of water normally expected for domestic supply (4-10 gallons per minute). However, with an adequate storage tank, a well producing as little as one g.p.m. can be sufficient for domestic needs. In many wells, several hundreds of gallons of water are already stored in the well column! For every foot of a 6 inch diameter well below water level, there are 1.5 gallons of water. When properly designed and managed, low-yield water wells can provide a viable supply for a home. Example: There are 1440 minutes in every day. If a well produces one gallon a minute of water throughout the day, 1440 gallons of water could be pumped into the storage tank. Assume that a family of four is served by the well, and that each family member uses 75 gallons of water a day, or 300 gallons. Total consumption for the entire family would be less than 21 percent of the water stored in the tank. The well would be required to produce water for a total of only five hours a day in order to replenish the water used. (Note - Check locally; some local rules may require a higher well yield to obtain approval for a home supply.) Hydrofrac techniques are often used to improve the yield of wells. The process involves down-hole equipment that creates great pressure in selected parts of the well to create and open up fractures.
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