Why Are Car Washes a Concern For the Environment?

• Oil and grease, which contain hazardous materials such as benzene, lead, zinc, chromium, arsenic, pesticides, herbicides, nitrates, and other metals
• Detergents, including biodegradable detergents, that can be poisonous to fish
• Phosphates, which are plant nutrients and can cause excessive growth of nuisance plants in water bodies
• Chemicals, such as hydrofluoric acid and ammonium bifluoride products (ABF), and solvent-based solutions that are harmful to living organisms
• Chemicals and oils used for the maintenance of cleaning machinery (for automatic systems)
• Debris that can clog storm sewer inlets and grates and thereby prevent storm water drainage to the sewer Washing vehicles on hard, impervious surfaces such as concrete areas can cause wash wastewater flow into storm drains. It is necessary to find out if area storm and sanitary sewers are combined or separate systems.

Many storm and sanitary sewers in the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) are combined before the final discharge point; therefore, most wastewater is treated before it is discharged to surface water bodies such as rivers, lakes, and streams. Many newer areas and other cities have separate sewer systems; therefore, wastewater discharged to storm sewers is discharged directly to water bodies without treatment to remove pollutants. Car wash wastewater can be harmful to humans, plants, and animals if released untreated to surface water bodies. Additionally, allowing wash wastewater to soak into the ground can be harmful because the wastewater may contaminate soil and groundwater. More information on how to prevent soil and groundwater contamination is presented later in this fact sheet.