There are several ways to drill a well, but
all drilling methods have one thing in
common—they bore a hole into the
ground. During the drilling process, the
well contractor examines the material
that is removed from the hole, looking for
samples of the local aquifers, and noting
the material on a driller's log. (The
driller's log documents what the contractor
finds and becomes the "as built" set of
plans for the well to be constructed.)
Using past experience as a guide, the
well contractor can estimate how far
down to drill to find water. But it is only
an estimate; in some areas, two or more
test holes must be drilled to find an
aquifer