Water removal from fuel tanks by selective absorption - facts.
All fuels contain some water in suspension.
Temperature changes can cause suspended water in the fuel to coalesce and settle out. External seepage or leakage during rains may also cause water to enter the tanks. Particularly in underground tanks, during ice or snow buildup or very heavy rains, leakage has been a problem. The requirements for containment dikes has contributed to the problem when drains become stopped up and do not allow water to get away. Water is more dense than fuel, so it always settles out to the bottom of the tanks .