The crew of a US Navy aircraft carrier recently discovered jet fuel contaminating the water supply. In doing this, the crew has to physically connect the ship's potable water system to its fuel oil system through piping. Aligning the potable water system and the fuel system involves opening valves that are normally locked shut in order to allow the two systems to connect. The fuel system is supposed to be depressurized, and the potable system should be pressurized. "Normally, if you flush out your fuel oil tanks — or your fuel oil system, any part of your fuel oil system — you should be watching for this problem, because you've connected the two systems.

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