Changes

==Technical specification==

[[Image:Baptist_drill_bit.jpg|thumb|Baptist drill bit. The arrow-shaped point is mounted on a ball, which acts as a check valve. The mud, loaded with clippings, passes the check valve and is carried up during the downward motion of the drilling stem. Depending on the type of soil, different drill bit designs are used.]]

Note that there is no need to enlarge the entire depth of the borehole: reaming until slightly below the lowest expected water table (the pump's water intake) is sufficient.

==Cost==