It is shown that the approach presented by Strack (Strack, O.D.L., 1989. Groundwater Mechanics. Prentice Hall, New Jersey) for determining the discharge potential for an area-sink leads to a function that is unique except for an arbitrary constant. The approach is applied to a special area-sink, namely one with an extraction rate that varies inside a polygon as a multi-quadric interpolator (Hardy, R.L., 1971. Multiquadric equations of topography and other irregular surfaces. Journal of Geophysical Research 76, 1905-1915). The principle of over-specification presented by Jankovic and Barnes (Jankovic, I., Barnes, R., 1999a. Three-dimensional flow through large numbers of spheroidal inhomogeneities. Journal of Hydrology 226, 224-233), is used to obtain an approximate solution. Several examples are presented herewith. (C) 1999 Elsevier Science B.V. All rights reserved.