The unit was developed to demonstrate how a diesel fuel water separator works. The unit has a fuel reservoir, water reservoir, pump, and the filter assembly. The pump located inside the cabinet continually circulates the diesel fuel through the filter. To demonstrate the system, the operator opens a valve under the water reservoir. The water is colored with a blue dye for better visibility. As the system operates, the water will collect in the bottom of the filter housing and turn on an indicator lamp, indicating the presence of water. The operator drains the water from the filter and puts it back in the water reservoir, ready for the next demonstration.