Non-stormwater Discharges from Residential Properties

Planning to wash your car in your driveway or host a charity car wash and wondering what to do about the wash water? Some non-stormwater discharges are allowed by the City's stormwater permit. Learn more about what's allowed and how you can stop pollution from reaching a river or stream.
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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 Portland residents and businesses to meet these requirements and to protect our rivers and streams.

Many storm drains in Portland flow directly to a river or stream, so only rain should go down a storm drain. Other substances can pollute streams, hurt water quality, and harm fish and other aquatic life.

Rules and Regulations

Portland City Code 17.39 prohibits discharges to the stormwater system of wash water and wastewater and discharges that are discolored, turbid, oily, or have a sheen. Examples include but are not limited to:

  • Wash water from washing home repair or automotive equipment or tools.
  • Wash water from cleaning pavement or buildings.
  • Sanitary wastewater.
  • Spilled materials or water from rinsing and cleaning pavement following a spill.
  • Heated or chlorinated water from a pool or hot tub.

Discharging of prohibited materials to the stormwater system may result in investigations, issuance of penalties, and required corrective actions. Collect and discharge these materials to the sanitary sewer. Contact Environmental Services for assistance. For a large volume discharge or a discharge that may have pollutants, prior written authorization may be required for discharge to the sanitary sewer. Find information on batch discharge authorization.

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

When Might Something Other Than Stormwater Be Allowed?

Discharges from residential sites that do not typically contain pollutants may be allowed to discharge to the stormwater system. The City’s Municipal Stormwater (MS4) Permit allows certain non-stormwater discharges. Examples include, but are not limited to:

  • Uncontaminated groundwater.
  • Natural sources, diverted stream flows, springs, or wetlands.
  • Landscaping irrigation water and lawn watering.
  • Uncontaminated air conditioning or air compressor condensate.
  • Uncontaminated foundation, footing, and crawlspace drainage.
  • Routine street and pavement rinse waters (provided that chemicals, soaps, detergents, steam, or heated water are not used) following cleaning with a broom prior to washing. See guidance below.
  • Routine external building rinse water (provided that chemicals, soaps, detergents, steam, or heated water are not used) following cleaning with a broom prior to washing. See guidance below.
  • Potable water sources.
  • De-chlorinated and cooled pool water or water from fountains or other water features. Learn more about how to safely empty your pool or hot tub.
  • Individual residential car washing and charity car washes. See guidance below.

Washing Your Car

Washing your car at your home and charity car washes are allowed by the City's stormwater permit. However, soap and wash water from car washing contains pollutants that are harmful to aquatic ecosystems. To minimize pollution:

  • Try washing your car without soap or with phosphate-free soap.
  • Wash the vehicle on the lawn or on gravel.
  • Go to a car wash.
  • Never wash engines, transmissions, undercarriages, or other oily parts or tools.
  • Never use heated water or steam.

Holding a charity car wash? Call Environmental Services to discuss best management practices and your intended car wash location.

Cleaning the Outside of a House or Your Sidewalk

The procedures below are examples of what you can do to prevent prohibited discharges of wash water. 

  • Clean during dry weather.
  • Sweep up all visible solids and absorb any oily stains prior to using wash water. Collect the sweepings for proper disposal.
  • Do not use water to remove paint or other solids.
  • Use brooms, or shop vacuums, or other similar cleaning methods that don't require water, when possible.
  • Use non-toxic cleaning methods. Do not use cleaning products that contain hazardous or toxic substances.
  • Only routine washing without chemicals, soaps, detergents, steam, or heated water is allowed to flow to the stormwater system. 

When cleaning, only use water for a final rinse.

Only rinse water can be discharged to the stormwater system! The following types of discharge are prohibited:

  • Water with visible floating materials and garbage.
  • Wash water from cleaning up stains and spills.
  • Cleaning products or chemicals.
  • Heated water or steam.

When your project can't meet these expectations, take steps to prevent prohibited discharges.

If the methods described above will not work for your project: 

  • Make sure that all water is contained and collected on your site. Do not allow wash water to flow into the street, to a storm drain, or to the stormwater system.
  • If storm drains are near your work area, place temporary barriers around them.
  • Capture wash water using a shop vacuum or similar tool and dispose of it properly.
  • Divert wash water onto a vegetated area or unpaved on your property where it will not enter the street. Or pour wash water into a sanitary sewer drain on your property.
  • Contact Environmental Services for assistance.