Gas stations can affect ground water or surface water quality due to various processes, equipment, and substances used on site. The aboveground and underground storage tanks used at gas stations have the potential to leak hazardous material that can impact ground water or surface water quality. Gas stations may also generate several sources of contaminants that can be washed away with stormwater, including oil and gas spills; engine and brake residues containing antifreeze, grease, oil, copper, and asbestos; engine degreasers containing copper and brass; radiator flushing residues containing lead, oil, and grease; and residue from engine washing containing aluminum and iron. Gas stations often have car washes, and vehicle wash water can carry sediments to surface waters and contaminate ground water by infiltration or drainage to subsurface wells and/or septic systems. Gas stations may also use underground injection wells to dispose of untreated fluids collected through open drains on station fueling pads and septic systems if located in an area that does not have access to a sewer system, both of which can impact ground water.