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