Borehole

A borehole is a deep and narrow shaft in the ground used for abstraction of fluid or gas reserves below the earth's surface. If the fluid reserve is under pressure, such as oil or gas, then extra machinery may be required. For water a special type of submersible pump is used to pump water up the rising main.

A borehole is also a commonly used term in the Environmental consulting and Engineering industries. A borehole is a small diameter hole drilled from the land surface to collecting soil samples. Soil samples are often then, tested in a laboratory to determine geotechnical properties or to assess levels of various chemical constituents. If the boreholes are installed for the purpose of assessing environmental conditions they may be completed as a Monitoring well to collect water samples.

Boreholes are most often used as a substitute for water wells, which tend to be shallower and wider than a borehole.

Boreholes are most heavily used in industrialised nations by water utilities, and by high volume water consumers such as golf courses and factories, for whom an independent water supply is an economical substitute for the metered supply of piped water. Although private domestic boreholes are usually free to operate, heavier users of a region's water table may be taxed by local authorities.

Boreholes are most important and widespread in the developing world, in regions where piped water supplies are not extensive. They can be the main water supply for a community, or sustain livestock and crops in difficult conditions. In either case, they require extremely robust design and implementation strategies to achieve sustainability.