[[Image:Jetting icon.png|right|80px]]
__NOTOC__<small-title />Jetting is also based on water circulation and water pressure. As opposed to sludging, water is pumped down the drill pipe and the ‘slurry’ (water and cuttings) is transported up the borehole between the drill pipe and the borehole wall. A motor pump is used to achieve an adequate water flow. The drill pipe may simply have an open end, or a drill bit can be added. Partial or full rotation of the drill pipe can be used. Thickeners (additives) can be added to the water in order to prevent hole collapse and reduce loss of working water (drill fluid).
Jetting is practiced in a wide range of varieties. The most simple consists of driving a plastic pipe down with water pressure from a motor pump (no drill bit and no rotation, with the water flow jetting the sand up). The depth is limited (no drill bit and extendable pipes). Other systems make use of extendable plastic or galvanized pipes and a drill bit and are rotated during drilling. With these systems greater depth can be reached.
===Suitable conditions===
[[Image:Manually rotated jetting.jpg|thumb|right|200px|Manually rotated jetting]]
[[Image:Typical drill bit.jpg|thumb|right|200px|Typical drill bit]]
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===Construction, operations and maintenance===
[[Image:Jetting.jpg|thumb|right|200px|Jetting. Credit: WEDC.]]
All drilling equipment, except the motor pump and some valves, is locally produced.
==Costs== ==Field experiences===
Jetting is mainly used in Niger, Chad, Madagascar, Nigeria, Senegal, Burkina Faso, Uganda, Kenya, Soudan, Benin, Sri Lanka and western countries.
===Manuals, videos, and links===
* [http://www.bsf-south-sudan.org/sites/default/files/SS+Tech+Guide--Hand+Pump+Equipped+Boreholes.pdf Technical Guidelines for the Construction and Management of Borehole Hand pumps.] UNICEF, April 2009.
* [http://www.drillingfab.com Drillingfab.] - Engine powered drilling equipment and small machines.
===Acknowledgements===
* [http://www.lboro.ac.uk/well/resources/technical-briefs/43-simple-drilling-methods.pdf 43. Simple drilling methods.] WEDC.