In addition to keeping solid particles out of the fuel supply and injection equipment, water in fuel must also be prevented from entering critical fuel injection system components. Free water can damage fuel lubricated components in the fuel injection system. Water can also freeze in cold temperature conditions and ice may block small fuel injection system passages thus cutting off the fuel supply to the rest of the fuel injection system.

Water can be removed from the fuel using two common approaches. The incoming fuel can be subject to centrifugal forces that separates the denser water from the fuel. Much better removal efficiencies can be achieved with a filter media that separates water. Figure 3 shows a filter using a combination of media-type and centrifugal approaches.

Figure 3. Fuel Filter Equipped with Water Separator