low cost, light weight well drilling rig that incorporates plastic drill stem

A low cost light weight hydrolic percussion well drilling rig that uses a single hollow metal pipe as a guide and combination check valve and dart bit with lenghts of threadable plastic pipe on top of the metal pipe for drill stem. Would allow for easy transport and light weight and low cost would allow poor people to manually drill their own water wells in developing countries. Wells could be open hole drilled with water and mud circulating up through the pipe to surface to bring cuttings up to be deposited in a settling pit. A simple tripod or cross beam would allow the string to be lifted and droped with inertia pumping circulating the fluid. Would have the simplicty of cable tool drilling and the versatility of rotary drilling and be cheap and easy to do.