Well

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A well is a hole or shaft dug or drilled to reach underground liquids, usually water. Most wells bring up groundwater from beneath the earth. Water is lifted by a pump or, in older systems, by hand with a bucket.

Wells come in several types. Hand-dug wells are opened with shovels and lined with brick or stone. They are cheap but can easily pick up surface contaminants and are hard to dig in hard rock. Driven wells are made by pounding a drive point and inserting a perforated pipe, then pumping water from the bottom. Drilled wells use machines to bore deep into the ground and are usually lined with steel or plastic casings, sometimes with screens to keep sediments out.

There are shallow or unconfined wells that tap the upper part of the groundwater, and deep or confined wells that reach deeper layers through an impermeable rock or soil layer. A collector well sits near a lake or stream and pulls water from the surface into the aquifer before pumping it up.

Choosing a good well site matters. Hydrogeologists study the ground, how deep the water is, and how quickly the aquifer recharges to pick a safe spot. Water quality is also important: shallow wells are more at risk of contamination than deep ones.

Common contaminants include bacteria, viruses, parasites, nitrates from sewage or fertilizer, pesticides, metals, and PFAS chemicals. To make water safe, people boil it, use chlorine in some cases, filter it, or treat it with ultraviolet light or specialized equipment. If a well becomes contaminated, fixing the well and its surroundings is essential, but cleanup can be expensive.

Wells need good construction and maintenance. The space around the well should be sealed, the top protected with a cap, and the area kept clean. Regular testing helps keep water safe. Environmental issues can include soil salination when the water table drops and methane entering some water supplies near certain wells.

Wells have played important roles in many cultures for thousands of years, appearing in stories and guiding the location of towns and communities.