Proper management of groundwater systems requires reliable assessment of its resources, particularly specification of spatial distribution and rates of recharge. Estimation of groundwater recharge based on measured water-table shape may be classified as an example of the “inverse problem”. Using “noisy” data, what is the typical case where measurement are discussed, leads to numerical instability and unreliable estimation of recharge. In this article the special modification to the flow equation is presented and verified in this article.