Wells

A well is a hole in the earth from which a fluid is withdrawn. Water wells are the most common type. Oil and natural gas wells are also common. Mining companies also pump steam and hot water down wells to remove salt and sulphur from deep in the ground (Gunning.)

Water Wells

The underground water that flows into wells is called ground water. Most of this water comes from rain that soaks into the ground and slowly moves down to the ground water reservoir, an area of soil and rock saturated with water. The top of this zone is the water table, the level at which water stands in a well that is not being pumped (Taylor.)

In damp places, the water table may lie just below the surface. It is easily reached by digging. A dug well is usually lined with bricks, stone, or porous concrete to keep the sides from caving in. In drier places, the water table may be hundreds of feet or meters down. It may be necessary to drill the well and sink pipes. Power-driven pumps usually draw the water out of deep wells (Berger, Cossi, Taylor.)

In some areas, underground water moving down from the slopes of hills and mountains becomes trapped under watertight layers of clay or shale. Wells drilled through these layers in valleys and plains run into water under pressure. Such wells are called flowing artesian wells (Eliav, Weiss.)

Many people depend on wells for their water supply, especially in rural areas. Underground water is usually pure, because soil makes a good filter. This water generally contains dissolved minerals. A well that taps water with a high mineral content is called a mineral well (Taylor.)