Originally Posted by
Chris Scott
In an ideal world, the water drains at the bottom of the wing tanks are dripped before the first flight of the day, and - as Dan_Brown points out - any kerosene would sink below the gasoline and sit on any water, given the time.
Well, no, not really. Water settles out because water and gasoline are imiscible. Gasoline and jet fuel mix just fine, and have no tendency to separate from each other. Depending on how much jet fuel was added, and how how much it was agitated as it was added, you might find that the mixture in the bottom of the tank had a greater percentage of Jet fuel than the top, but you aren't going to find a nice clear division, like you will with water and gas that has sat undisturbed overnight.