When dipping tanks, smear five to six inches of water paste at the bottom of the dip stick or tape. Water paste is available from petroleum equipment suppliers. If water is present, the paste will change color, from yellow to red. Water invades tanks through leakage or condensation. Spillage Spillage usually occurs because of operator negligence when filling equipment or fuel storage tanks.
Spills can also occur when the fuel in a tank heats and expands, and is forced through the vent cap.
Therefore, above ground tanks shouldn't be filled to more than 90 per cent of their capacity. Losses due to spillage are usually confined to the cost of the fuel spilled and surface cleanup. Care must be taken to prevent spilled fuels from catching on fire. Ignition can easily occur when fuel overflows a vehicle's tank and comes in contact with a hot exhaust system. Cleanup costs and losses due to leaks and spills can be reduced by proper siting and installation of storage tanks.