[[Image:Rota sludge in action.jpg|thumb|right|200px|Rota sludge in action]]
[[Image:Deep drilling with the rota sludge.jpg|thumb|right|200px|Deep drilling with the rota sludge]]
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The Rota Sludge is a manual drilling technique based on the [[Sludging - Asian sludge |Asian sludge]] technique, and adapted for harder soil types. To drill through the harder layers, a hardened drill bit and weight have been added. Just after the downward movement of the drill pipes the drill bit is rotated a quarter turn, thus chiselling the bottom of the hole. Water is circulated to bring the cuttings to the surface.
The Rota-Sludge was developed by the [http://www.practicafoundation.nl/products/drilling-wells/ Practica Foundation].
===Suitable conditions===
Suitable for unconsolidated formations: Sand, silt and clay. Because of the rotation and the drill bit, it is possible to penetrate softer-consolidated formations such as stiff clays, soft sandstone, and weathered laterite.
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===Construction, operations and maintenance===
[[Image:Diagram of a rota sludge.jpg|thumb|right|200px|Diagram of a rota sludge]]
[[Image:Rota_sludge_well_drilling.PNG|thumb|right|200px|Drilling a 20 m deep well in Chinandega, Nicaragua, with the Rota-sludge method. Photo: Netherlands Water Partnership.]]
All drilling equipment is locally produced.
===Costs===
In India, the cost of a well made with Rota-sludge is about US$ 30. In Nicaragua, this varies from US$ 80 to US$ 400.
The cost of introduction varies between US$ 5,000-20,000 per project, including hand-on training, drill set and drilling of test wells.
===Field experiences===
The Rota Sludge is used in Nicaragua, Tanzania, Madagascar, Ghana, Senegal, Mauritania and Niger.
===Manuals, videos and links===
* Arjen van der Wal & Robert Vuik, [http://www.practica.org/wp-content/uploads/services/publications/drilling%20manuals/EN/sludging%20_final%20version_lr%20310811%20full%20ENG.pdf Sludging: Manual Drilling Series. Technical Training Handbook on Affordable Manual Well Drilling]. Practica Foundation, June 2011 (2nd edition). French version: [http://www.practica.org/wp-content/uploads/services/publications/drilling%20manuals/FR/sludging_final%20version-lr%20310811%20full%20FR.pdf FORAGE A LA BOUE : Serie forage manuel].
=== Acknowledgements===
* The basis for the material on this page was obtained from a desk study shortly to be published on the website of the [http://www.practicafoundation.nl/ Practica Foundation], and from the [http://www.rural-water-supply.net/ Rural Water Supply Network], and specifically its [http://www.rural-water-supply.net/en/implementation/manual-drilling manual drilling section].
* [http://www.lboro.ac.uk/well/resources/technical-briefs/43-simple-drilling-methods.pdf 43. Simple drilling methods.] WEDC.