Oil/Water Separator

An oil/water separator (OWS) is a treatment device that separates petroleum-based hydrocarbons (motor oil, diesel, gasoline residues, hydraulic fluid) from wastewater before discharge to the sewer system or the environment. They are installed at car washes, auto repair facilities, fueling stations, parking garages, fleet maintenance facilities, and industrial sites where petroleum contamination of wastewater is a regulatory concern.

Oil/water separators exploit the density difference between water and oil — oil floats and can be skimmed or accumulated in a chamber separate from the water outlet. Like grease traps, they require periodic cleaning to remove accumulated oils and sediment. Discharge of petroleum-containing wastewater to municipal sewers is regulated under the Clean Water Act and Minnesota Pollution Control Agency rules — non-compliance can result in significant fines.

What This Means for You

If your facility has an oil/water separator, it must be maintained on a schedule that prevents overflow. Document every service call for regulatory compliance. If your separator is aging or undersized for current operations, consult with a licensed professional about upgrading — an enforcement action for improper discharge is far more expensive than proper maintenance.

Related Terms

Sand Trap (Carwash)  ·  Grease Interceptor  ·  Grease Trap

Related Services

→ Car Wash Sand Traps