Need procedures for cost effective drilling of deep borewells in Africa

In a remote place in Africa(Niger) , lack of access to water is a major problem. A NGO has started to target this issue by building bore wells. Shallow wells in this area has failed previously. Now they are building borewells with depth between 250 mts - 300 mts. using steel tubes. Depending on the few companies in that area, cost of such borewell is coming to a lot.
I am searching for ideas from India which can reduce such huge costs. Any procedure to dig the wells that can be semi-automatic or any equipment that can be purchased where cost of it can be recovered most efficiently will be greatly helpful.


Dr.Deepesh Reddy Vendoti,
Yale University, MPH,
School of Public Health.