The “Baptist” drilling approach, developed by Terry Waller of Water for All, International (http://waterforallinternational.org/) is a very low-cost and practical approach to developing boreholes in rural areas.
The technique itself is based on a principle used for thousands of years, most notably by the ancient Chinese who used bamboo and their hands instead of iron and a check-valve, that involves the recycling of water from the bottom of the hole through the surface, where sediment settles out and the “clean” water re-enters the hole and carries mud, sand and other sediment through the hollow boring rod.
The basic approach is as follows:
- Set up a wooden stand about 2-3 meters above the ground with a cross piece to hold a pulley directly above the point of penetration.
- Run a rope attached to simple 1.5-meter long metal, interlocking pipes attached to a check-valve and a simple bit (several types of bits are developed for different soil types).
- Dig out a 1 x 1 meter square pit for water to settle with a small channel for re-entry into the hole.
- Find the nearest water source and fill as many large drums of water as you can.
- Begin with the 1st 1.5-meter section of drilling rod without attaching it to the rope. Up and down, up and down. Add lots of water, especially at this beginning stage.
- Gather 6 or more of your closest friends and have them stand with the rope to pull the drilling rod up and down as two or three people stand under the pulley to guide and slam the drilling rod down into the ground.
- Repeat this up-down process until the depth of the borehole is sufficient. For unconsolidated material, this usually takes 2-3 days to penetrate 20-30 meters.
- Add casing, gravel pack, and pump.
- Cap well
This approach is very effective in unconsolidated sediments with relatively shallow water table (up to 20 – 30 meters).
It is not applicable for drilling through bedrock or even large boulders.
It is very low-cost, compared to conventional approaches.
In Zambia, a drilling team can profitably drill wells for roughly $800, as compared to $4,000 for a mechanized rig.