Produced Water is a major challenge in the oil and gas industry. Water production increases worldwide as more reservoirs depleted over time thus more resources needed to handle the unwanted produced water. Managing the subsurface water conformance maximizes hydrocarbon production and reduces operating cost that is mainly expected from the unwanted water production. It is important to identify the water source to solve any problem related to the unwanted excessive water production. Once the mechanism of the water production is understood, an effective strategy can be designed to detect and control the produced water. Different technologies and methods have been developed to control produced water. For example, Production Logging Tool (PLT) and Chan's WOR diagnostic plot are two common methods for determining the presence and causes of the unwanted excessive water production. In this study, Downhole Water Sink (DWS) completion technology is adapted to maximize reservoir recovery by reducing water cut with oil production, the excessive water is produced through a bottom completion and the oil is produced from the top completion. The design of a successful DWS requires detailed planning for the completion location and the production strategy. The aim of this study is to evaluate DWS technology performance in vertical oil wells located in Middle East Reservoir, which have severe water coning. In addition, economic analysis results were obtained by comparing the conventional wells with DWS wells to investigate the effect of DWS in reducing the operating cost. Results showed that the DWS completion minimized the water production by 18% and enhanced oil production by 26% compared to the conventional completions. In addition, several diagnostic tools applied to evaluate the water to enhance the proposed solution in which is applied to the candidate reservoir.