The withdrawal method for protecting the uncontaminated part from the spread of contaminants was suggested by a simultaneous equation. The formulation of them is based upon the build up of the ridge part between the contaminated and uncontaminated parts that resulted from the efficient use of barrier wells. The quality in the withdrawn groundwater depends upon the heads at wells no. 5 and 6. The determination of pumping rates and qualities with changing the heads at wells no. 5 and 6 should be given by considering the demand for water use and the capacity and cost for removing the contained contaminants. The results of this study should be used in taking a plan for supplying water use as well as preventing the spread of contaminants from some known contaminated sources.