The paper presents a simple mathematical model which allows prediction of the behaviour of the water table in a low pressure water well which does not flow to surface. The derived relations enable computation of the permeability and skin factor of the water zone. Unlike the type-curve method used for interpretation of "slug test" data, the permeability and skin are computed using a straight-line approximation. The slope of the straight line and its intersection with the ordinate axis are used to interpret the test data, The presented method is very simple and yields unique results.