What the Bay Area stormwater permit means for pressure washing commercial property: the non-stormwater ban, city enforcement and wash-water capture practices.
Bay Area Cities Must Prohibit Non-Stormwater Discharges And Require Practices That Keep Pressure Washing Water Out Of Storm Drains. This Paper Explains The Permit Rules, City Enforcement And Recommended Wash-Water Capture.
Download PDFExecutive Summary
Water that runs off a pressure-washed sidewalk, plaza or building in the Bay Area does not go to a treatment plant. As the Alameda Countywide Clean Water Program puts it, water flowing into storm drains "travels directly to local creeks and then to San Francisco Bay." That is why wash water is regulated, and why property managers should know what their cities are required to enforce.
Key Points
- Non-Stormwater Is Prohibited: Bay Area cities must "effectively prohibit the discharge of non-stormwater" into storm drains and watercourses. MRP A.1
- Pressure Washing Is Named: Cities must require BMPs that prevent polluted wash water from pavement, sidewalk and plaza cleaning and outdoor pressure washing from reaching storm drains. MRP C.2.b
- Mobile Cleaners Are Inspected: Each city runs a mobile business program covering power washing, with BMP standards, enforcement and inspections. MRP C.5.e
- Capture And Proper Disposal: County guidance: contain, collect and send wash water to the sanitary sewer (with agency approval) or haul it off-site. Clean Water Program fact sheet
Why Wash Water Is Regulated
The federal Clean Water Act regulates municipal stormwater through National Pollutant Discharge Elimination System (NPDES) permits. In the Bay Area, the San Francisco Bay Regional Water Quality Control Board issues one Municipal Regional Stormwater NPDES Permit (MRP), Order No. R2-2022-0018, which serves as an NPDES permit under CWA section 402 and took effect July 1, 2022. MRP Findings 21
The MRP covers the cities and agencies of Alameda, Contra Costa, Santa Clara, San Mateo and Solano (Fairfield, Suisun City, Vallejo) counties, organized into countywide programs such as the Alameda Countywide Clean Water Program, the Santa Clara Valley Urban Runoff Pollution Prevention Program and the San Mateo Countywide Water Pollution Prevention Program. MRP cover pages
What The Municipal Regional Permit Requires
Discharge Prohibition A.1
Permittees must, within their jurisdictions, effectively prohibit the discharge of non-stormwater ("materials other than stormwater") into storm drain systems and watercourses. NPDES-permitted discharges are exempt, and Provision C.15 sets out conditionally exempted categories. MRP A.1
Pavement Washing (C.2.b)
Cities must implement and require BMPs that prevent polluted wash water and non-stormwater from reaching storm drains from pavement, sidewalk and plaza cleaning, mobile cleaning, outdoor pressure washing and washing down of trash areas. BMPs for washing outside areas of human habitation must include sanitizing procedures. The permit points to the BASMAA Mobile Surface Cleaner Program and directs cities to coordinate with sanitary sewer agencies on whether sewer disposal is available with appropriate approvals and pretreatment. MRP C.2.b
Commercial Sites And Mobile Businesses
Cities keep an inspection plan for commercial and industrial sites, with authority to require BMPs for areas such as outdoor parking areas, outdoor wash areas and waste storage areas, backed by an Enforcement Response Plan. MRP C.4 Separately, each city must run a mobile business program covering power washing, steam cleaning and graffiti removal, including minimum BMP standards, an enforcement strategy, an annual inventory, outreach and inspections. MRP C.5.e
What This Means For Owners
The permit itself is addressed to cities, but cities enforce it against the properties and businesses where discharges happen, including commercial sites and the mobile cleaners working on them. A property manager's practical exposure is that the discharge happens on the property; asking how a contractor handles wash water is part of vetting that contractor. Specific liability depends on local ordinance.
Best Management Practices
| Surface | County Guidance |
|---|---|
| All Wet Cleaning | Sweep first; minimize water; avoid soap where possible ("Even biodegradable soap is harmful to the environment"). |
| Sidewalks, Plazas, Driveways, Garages | Collect debris; dry-clean oil spots; contain and collect wash water and discharge to sanitary sewer or haul off-site. |
| Heavy Oil Deposits | Discharge to sanitary sewer via an oil/water separator if possible, after discussing with the site operator and wastewater agency. |
| Glass And Steel Buildings | Block storm drains; direct wash water to sanitary sewer or collect and haul off-site. |
| Possible Lead Or Mercury Paint | Block drains, collect, pump to a tank; sanitary sewer or hazardous waste disposal as required. |
| Graffiti Removal | Block the storm drain and collect wash water; discuss with site operator and wastewater agency. |
Collection tools named in the guidance include gravel bag berms, wattles and mats to contain the area, and a wet-vac or pump to move water to a sanitary discharge point or tank. The local wastewater agency must be contacted before any sanitary sewer discharge. Clean Water Program, Tips For Surface Cleaning & Power Washing (Nov 2022)
Sources
- SF Bay Regional Water Quality Control Board, Municipal Regional Stormwater NPDES Permit, Order No. R2-2022-0018 (amended By R2-2023-0019). waterboards.ca.gov/sanfranciscobay/…
- Alameda Countywide Clean Water Program, Tips For Surface Cleaning & Power Washing. cleanwaterprogram.org/wp-content/uploads/…
- U.S. EPA, NPDES Stormwater Discharges From Municipal Sources. epa.gov/npdes/…
This paper summarizes regulations and agency guidance for general information and is not legal advice. Requirements may change and vary by city; consult the current text, your local agency and qualified professionals.
