Tube well

A Tube well as the name implies is simply a tube or pipe bored into the underground reservoir, fitted with a strainer at the lower end and worked at the top by a pump, to lift water for irrigation.A Tube well is type of water well in which a long 5 to 8 inch wide stainless steel tube is inserted in the well.This tube is then extended to the underground water below the lower surface of the well.

Temporary Reservoir

In the villages of Pakistan, a small reservoir of water is made at the outlet of the tube well, which is used to have a bath and also for recreational purposes. Children enjoy very much by such type of bath

Drive Mechanism

The tube is connected to a pump which is driven by the large diesel engines in the past but now electric motors are being used instead of engines. This is much cheaper source of power.

Sailent Features Some salient features of a simple tubewell are as followstubewell

The casing - often in PVC, which is both cheap and inert - houses the inlet, cylinder, piston valves and rising main of a "down-the-hole" type handpump, which can be lifted out for maintenance or repair.

Seepage down the tubewell bore is prevented by the sanitary seal. Seepage from the ground above the aquifer is excluded by the lengths of plain casing. Water to be pumped is admitted through slots in the lower lengths of casing.

Casing to support the external surfaces of the borehole against collapse may be needed, either temporarily or permanently, but is not shown.

Water abstracted from aquifers in relatively soft ground usually contains sand or silt particles, which are liable to cause rapid wear to pump valves and cylinders (and dissatisfaction among consumers).

Methods of preventing these particles from reaching the pump are of two general types:

ScreeningThe drawing shows slots in the PVC casing which can be cut on site, using a hacksaw. More elaborate, and far more compact, screens are available commercially; some can be bolted on to pump inlets. Materials used include woven wire and man-made fabric; the latter can be wrapped around the pump inlet assembly.

Sand/gravel packingThe drawing shows graded sand and gravel, which is placed from the top of the borehole. More compact, pre-bonded, packs of sand and/or gravel are available commercially; some of these can also form part of the pump inlet assembly.

Screening is nearly always needed, in some form. Sand and/or gravel packing is meant to eliminate particles from the water before they reach the screen and would otherwise have passed through the screen.