One of the functions of a cowl area in a vehicle is the separation of water and air flow. A well working separation of water droplets in the airflow is required under all circumstance, to avoid the blower or air filter to become wet. Airflow calculations help improving the design of the cowl to achieve an effective water droplet separation and simultaneously low pressure losses. The proposed design has been tested under sever conditions. Test results were compared to theoretical results and revised design requirements will be proposed.