What is Water?

 

Water is a clear, colourless, odourless, and tasteless liquid, H2O.  It is essential for most plant and animal life and the most widely used of all solvents.  Water at freezing point is 0C (32F) and boiling point is 100C (212F).  Waters specific gravity is (4C) 1.0000, its weight per gallon is   (15C) 8.338 pounds (3.782 kilograms).

 

 

Bored Well

Water Well


A water well is an artificial excavation or structure put down by any method such as digging, driving, boring, or drilling for the purposes of withdrawing water from underground aquifers.

 

A hand drawn water well

                                                                      A hand-drawn water well.


Well water may be drawn via mechanical pump (such as an electric submersible pump) from a source below the surface of the earth, or drawn using containers, such as buckets, that are raised mechanically, or by hand. Wells can vary greatly in depth, water volume and water quality. Well water typically contains more minerals in solution than surface water and may require treatment to soften the water.

 

Ground Water

 

water being lifted from a traditional well

                                                           Water being lifted from a traditional well


A well is made by reaching ground water in the water table. Ground water is stored naturally below the earth's surface. Most ground water originates as rain or snow that seeps into the ground and collects. Most rainwater is absorbed by the ground and fills the tiny spaces between soil particles. However, excess water runs over the top of the soil until it reaches a river, stream, or reservoir.  Runoff water brings pollutants it encounters along the way to the reservoir.


As water seeps into the ground, it settles in the pores and cracks of underground rocks and into the spaces between grains of sand and pieces of gravel. In time, the water trickles down into a layer of rock or other material that is water tight. This water tight zone collects the ground water, creating a saturated zone known as an aquifer.


The water in the earth that these wells obtain is at a place in the ground known as the water table. The water table is the level of the ground water below the earth's surface. This table is measured by the depth of the upper limit of the Aquifer. The water table can be lowered by lack of precipitation or overdraft.


In a damp area, the water table can be reached simply by digging. In this case the well walls are usually lined with brick, stone, or concrete in order to keep the sides from caving in on the well. A dug well can be up to 50 feet deep, and has the greatest diameter of any of the well types. Well water that contains a high number of dissolved minerals is called a mineral well. Except for areas containing Karst formations, underground water is considered fairly clean because soils create a filter that remove large toxins.
Types of water wells

Dug Wells
 

brick lined water well

                                                              100 year old, brick lined water well.


Until recent centuries, all artificial wells were pumpless dug wells of varying degrees of formality. Such primitive dug wells were excavations with diameters large enough to accommodate muscle-powered digging to below the water table. Relatively formal versions tended to be lined with laid stones or brick; extending this lining into a wall around the well presumably served to reduce both contamination and injuries by falling into the well. The iconic American farm well features a peaked roof above the wall, reducing airborne contamination, and a cranked windlass, mounted between the two roof-supporting members, for raising and lowering a bucket to obtain water.
More modern dug wells may be hand pumped, especially in undeveloped and third-world countries.  Note that the term "shallow well" is not a synonym for dug well, and may actually be quite deep.

Driven Wells
Driven wells consist of a series of pipes with a point and a perforated pipe at the end. The point is driven into the ground, thus the name driven, to a depth of up to 75 feet[1].

 

Drilled Wells
 

Old Cable Tool Carrier

                                                                           Cable Tool Carrier


Cable tool water well drilling rig. These slow rigs have mostly been replaced by rotary drilling rigs. 
Drilled wells can access water from a much deeper level by mechanical drilling.


Drilled wells are typically created using either top-head rotary style, table rotary, or cable tool drilling machines, all of which use drilling stems that are turned to create a cutting action in the formation, hence the term 'drilling'. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 20 to 600 feet, but in some areas can go deeper than 3,000 feet.


Rotary drilling machines use a segmented steel drilling string, typically made up of 20 foot sections of steel tubing that is threaded together, with a bit or other drilling device at the bottom end. Some rotary drilling machines are designed to install (by driving or drilling) a steel casing into the well in conjunction with the drilling of the actual bore hole. Air and/or water is used as a circulation fluid to displace cuttings & cool bits during the drilling. Another form of rotary style drilling, termed 'mud rotary', makes use of a specially made mud, or drilling fluid, which is constantly being altered during the drill so that it can consistently create enough hydraulic pressure to hold the side walls of the bore hole open, regardless of the presence of a casing in the well. Typically, boreholes drilled into solid rock are not cased until after the drilling process is completed, regardless of the machinery used.


The oldest form of drilling machinery is the Cable Tool, still used today. Specifically designed to raise & lower a bit into the bore hole, the 'spudding' of the drill cause the bit to be raised & dropped onto the bottom of the hole, and the design of the cable causes the bit to twist at approximately 1/4 revolution per drop, thereby creating a drilling action. Unlike rotary drilling, cable tool drilling requires the drilling action to be stopped so that the bore hole can be bailed or emptied of drilled cuttings.


Drilled wells are typically cased with a factory made pipe, typically steel (in air rotary or cable tool drilling) or plastic/PVC (in mud rotary wells, also present in wells drilled into solid rock). The casing is constructed by welding, either chemically or thermodynamically, segments of casing together. If the casing is installed during the drilling, most drills will drive the casing into the ground as the bore hole advances, while some newer machines will actually allow for the casing to be rotated & drilled into the formation in a similar manner as the bit advancing just below. PVC or plastic is typically welded & then lowered the drilled well, vertically stacked with their ends nested & either glued or splined together. The sections of casing are usually 20' or more in length, and 6" - 12" in diameter, depending on the intended use of the well and local ground water conditions.  When groundwater is encountered, the well is washed of sediment and a pump installed. This is the cheapest and simplest type of water well known today, however it is only useful at relatively shallow depths and for small capacity wells.


In addition, wells are typically capped with either an engineered well cap or seal that vents air through a screen into the well, but keeps insects, small animals, and unauthorized individuals from accessing the well.

 

The above information was received from the Wilipedia Encyclopedia under Water Well. 

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