Implementation • Handpump Technology

Baptist Drilling

Description: Terry Waller of Water for All in Bolivia developed Baptist drilling in 1993. It is a hybrid between sludging and percussion drilling. The main difference is that while hand sludging relies on a person’s hand at the top of the drill pipe as a valve, the Baptist method uses a valve, incorporated into the bit at the bottom of the drill stem.

The drill pipe and bit are normally not removed from the borehole until drilling is finished. Drill cuttings are suspended in the drilling fluid (mud) and pumped to the surface. The percussion action is performed by lifting the drill stem using a rope and pulley attached to a simple (wood or bamboo) derrick. Drilling diameter is kept small as possible with standard drill bits made from 1¼” (32 mm) internal diameter iron plumbing accessories. With reamer bits the hole diameter can be increased to 150 mm. The drill pipe is iron or galvanized iron for the bottom 3m, with PVC pipe extensions to keep the equipment light. The drill is lifted with a rope and pulley and the drill can be rotated some 90 degrees. Some drillers have motorised the lifting action.

Capability: This technique works best in sand, loam, small gravel and light rock. It will not penetrate hard rock or boulders. The standard drill bits work through sticky and even consolidated clays. Optimum results in varying conditions are obtained with an array of different bits, including those without a valve. In layers of pure clay or gravel, progress is slow compared to sludging, since the clay has to be pounded into suspension and stones have to be ground to small pieces to pass through the footvalve. With the Shipo version of the Baptist as used in Tanzania, stones smaller than 3 cm can be lifted in one piece because of the use of an open drill bit combined with sludging. Drilling speed is variable with different soil conditions and crews, but over 15 m per day have been obtained in favourable conditions.

Equipment and Cost: The core element of the rig can be made in almost any arc-welding workshop, using materials that can be found locally. A complete Baptist rig, all tools included and capable of drilling up to 30 m deep, can be assembled in Nicaragua for about US$ 150. In Bolivia, the wells cost around US$2 per meter (well casing and a low-cost PVC pump and small provision for rig maintenance). Prospective well owners provide all labour.

Locations: Water for All in Bolivia provides training and advice on purchase of materials to communities (Water Clubs) that want to drill their own wells. Farmer-to farmer training is used to pass the method onto other communities. To date, over 2,000 Baptist wells have been drilled in 12 countries. Most wells are in Bolivia, followed by Nicaragua, Sri Lanka and Cameroon with trials in Ethiopia, Kenya, Tanzania, Zambia, Mozambique, Malawi, Togo, Mexico, Argentina, Costa Rica, Nigeria and Mali, the Netherlands, USA and Chile.

Documentation: