oil storage tanks steel tanks above ground storage tanks OIL STORAGE TANKS Controlling Water Pollution From Oil Storage Tanks. Thousands of oil storage tanks dot the landscape of oil-rich counties in southern and central California. Oil storage tanks occasionally leak. The risk of leakage increases as the oil tank ages. If the oil storage tank is underground, a small oil leak may go undetected for a long period of time. Because underground fuel oil storage tanks are buried, it is difficult to tell whether the tank is leaking or not. This circular concerns explosions in fuel oil storage tanks caused by overheating of their contents. Manufacturer of liquid level indicators, bolted water and oil storage tanks and welded water and oil storage tanks. There are two types of fuel oil storage tanks.