Prevent Pollution when Washing Vehicles and Equipment

Wash water from cleaning vehicles or equipment may contain detergents, degreasing chemicals, oils, suspended solids, heavy metals, and organics and is prohibited by city code from discharging to the stormwater system.

The City's Role

The federal Clean Water Act requires cities to set rules and regulations to protect the city's sewer and stormwater systems and its watersheds. Environmental Services works with business and industry to meet these requirements.

Many storm drains in Portland flow directly to our rivers and streams without treatment. If not properly contained, the wash water from vehicle and equipment washing can introduce pollutants into the stormwater system. These pollutants can then flow to a river or stream, harming water quality, fish, and other aquatic life.

Even phosphorus-free, biodegradable, or “nontoxic” cleaners can threaten surface waters. Biodegradable soaps reduce the oxygen in water when they break down, which threatens aquatic life. Wash water in a stream may result in warm, cloudy, low-oxygen water. This creates deadly habitats for fish, frogs, water bugs, and other aquatic life.

Rules and Regulations

The 2020 Source Control Manual describes requirements for equipment and vehicle washing that all new and remodeled areas must meet. The requirements go beyond what is described on this page and include pavement, covering, containment curbs, sanitary drainage, and wastewater treatment, to keep washing area pollutants contained and prevent mobilization of contaminants from the washing areas.

Portland City Code 17.39 prohibits the discharge of wash water into the stormwater system. The discharge of wash water may result in investigations, issuance of penalties, and required corrective actions.

Portland City Code 17.32 prohibits directing water from any source to run onto any City sidewalk, street, easement, or right-of-way without first obtaining authorization or approval.

Prevent Pollution through Best Management Practices

Follow these best management practices to prevent pollution from vehicle and equipment washing:

  • Use a dedicated wash pad connected to the sanitary sewer or install a closed-loop wash water recirculation or recovery and reuse system.
  • Use a curb to contain the wash water in the dedicated washing area.
  • Refrain from using metal brightening chemicals or cleaning products.
  • If a dedicated wash pad is not feasible, take vehicles to a commercial vehicle washing facility with an approved disposal system.
  • Review the specific wash and spill prevention plans for your facility.

Hiring a Mobile Washing Service

If hiring a mobile washing service, ensure the business implements appropriate best management practices to prevent a prohibited wash water discharge from your site.

  • Establish a dedicated washing area and ensure washing operations that use soaps, detergents, hot water, or steam are conducted on a paved surface so wash water can be collected and discharged to a sanitary sewer or recycling system.  
  • Ensure the mobile washer contains and collects all wash water. Mobile washers typically use portable curbs, catch basin covers, and pumps.
  • Ensure the mobile washer is aware of the location of storm drains in the washing area. Check to be sure all storm drains are blocked before cleaning begins.
  • Ensure the mobile washer prevents overspray from impacting/discharging in areas outside the washing area.
  • All debris and residual material from washing activities must be cleaned up after by rinsing, recovering, sweeping, or vacuuming the area to prevent the discharge of residual materials to the stormwater system. Ensure rinse water is collected for discharge to the sanitary sewer.
  • Ensure the mobile washer holds a Discharge Authorization with the City. If a mobile washer generates a prohibited discharge from your site, your facility may be held responsible.

Failure to implement applicable best management practices listed above may result in the discharge of pollutants which is a violation of Portland City Code. The City will issue enforcement action in the form of a civil penalty if pollutants are discharged from your facility. Appropriate measures to prevent the discharge of pollutants are required.