A fuel water detector can be used in jet fuel to find out if there is any water that cannot be seen with the naked eye. In the case of the Shell Water Detector, it’s a capsule that you attach to a syringe, which you use to draw out 5ml of jet fuel. When testing jet fuel with the Shell Water Detector, watch to see if it changes colour from yellow to blue; this means that there is water. (Box of 80 tests)