Mobile Washing and the Clean Water Act: What Contractors Need to Know About Runoff
Quick answer: Under the Clean Water Act, letting wash water containing pollutants (oil, grease, detergents, metals, or dirt) enter a storm drain is typically an illegal discharge, because storm drains usually flow untreated to local waterways. Mobile washing contractors are generally responsible for capturing that water and disposing of it properly, often through recovery and filtration equipment.
Why Storm Drains Are the Problem
Most storm drains are not connected to a treatment plant. Whatever goes in, including wash water full of oil and soap, reaches creeks, rivers, and lakes. That's why regulators treat runoff from washing as pollution, even "biodegradable" soap.
Who Enforces It
Federal: The EPA sets the framework under the Clean Water Act.
State: Most states run their own permit and enforcement programs.
Local: Cities with stormwater (MS4) permits often have their own ordinances and inspectors, and are usually the first to act.
Penalties can be substantial, and the property owner and contractor may both be held responsible.
Compliant Disposal Options
Method | How It Works | Notes |
Discharge to sanitary sewer | Recovered water goes to a treatment plant | Requires permission from the local sewer authority |
Hauling | Water is collected and taken to an approved facility | Ongoing cost per load |
Filtration and reuse | Water is treated and reused on site | Reduces disposal volume and water costs |
Discharge to landscape | Clean water only, where local rules allow | Rarely allowed for degreasing work |
What Compliance Looks Like on a Job Site
Block or cover nearby storm drains
Contain water with berms or mats
Recover water with a vacuum system
Filter, separate, or store it
Dispose of it through an approved route
Keep records of where water went
Compliance Is a Sales Advantage
Large customers, including municipalities, fleet operators, and property managers, increasingly require contractors to show a recovery plan. Contractors with recovery equipment can bid on work others can't.
FAQ
Is biodegradable soap allowed to go down storm drains? Generally no. Biodegradable does not mean non-polluting, and wash water also carries oil and dirt.
Do I need a permit to wash vehicles on site? It depends on your location. Check with your local stormwater authority and sewer district.
Does clear water need to be recovered? Rules vary. Plain water rinses may be allowed in some areas, but anything with soap, heat-loosened grease, or debris usually is not.
This article is general information, not legal advice. Check your state and local regulations.
Need a recovery solution? Text us or call 800-897-7515 to talk through water recovery options for your operation.
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