Water that may collect on the bottom of motor fuel storage tanks.
Oil and water, as the old saying goes, don’t mix. If water finds its way into a gasoline storage tank, the water will not combine with the gasoline. Instead, it will settle to the bottom of the tank.
The presence of water on the tank bottom does not cause a serious problem so long as the intake port for the pumping unit is above the level of the water. Tank water bottoms should, however, be removed from storage tanks from time to time. Water bottoms in steel tanks can cause corrosion.
A direct means for removing tank water bottoms is simply to lower a suction hose to the bottom of the tank and pump out the water. The pumping action should stop as soon as the presence of gasoline is detected in the liquid flowing from the discharge hose.
Environmental regulations prohibit the discharge of pumped-out water bottoms into adjacent soil or storm sewers. Instead, the liquid should be discharged into drums and hauled away for proper disposal, or directed through a portable oil/water separator or other treatment method.