MBOARAHARINJAKA RASOAMANAMBOLA via web
Manually drilled wells can be to 2-5 times cheaper than boreholes drilled with industrial rigs while providing the same quality well. Where applicable, manual well drilling has proven to be an appropriate asset in development and emergency sectors as it increases access to safe and affordable drinking water and stimulates livelihood of local entrepreneurs. Several techniques are used for manual drilling: "Rota sludge, Jetting, Rotary jetting, percussion" ect.... But with the same weak point: (1) hard formation is difficult to penetrate/even impossible. (2) beyong 5days of drilling, manual drilling is physically and mentaly exhausting.
see in this link the repport of the improvement of the manual drilling techniques: http://practica.org/publications/capstan-based-design-mechanizing-manual-well-drilling/.