How many gallons do you need to recover — and what's your risk class? Enter your job details below, get an instant answer.
Job Type *
🏠 House Wash
🏚 Roof Soft Wash
🛣 Concrete / Flatwork
🚛 Fleet Wash
🏢 Commercial Building
Area Cleaned (sqft)
2,000 sqft
10020,000
Distance to Storm Drain (ft)
75 ft
5 ft300 ft
Slope Toward Drain
Flat <2%
Mild 2–8%
Steep >8%
Surface Absorption
Impervious
Semi-pervious
Pervious
Chemistry Used
SH Concentration (applied %)
0% (water only)
0% (none)12% (12.5% stock undiluted)
Surfactant present?
Degreaser or acid cleaner?
Live Results
—
est. runoff gallons
—%
capture required
—
gallons to recover
—
⚠ Chemistry Risk Flags
Recommended Capture Methods
Download Your NPDES Compliance Brief
Get a 4-page PDF with your job's risk class result, stormwater law summary, capture method matrix, and PAR proof CTA — ready to print for your compliance binder.
Your risk class + exact runoff volume
NPDES law summary + 40 CFR 122.41 citations
Capture method matrix for your job type
Chemistry risk flags & substrate warnings
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Check your inbox for the PDF download link. In the meantime:
Do pressure washers need an NPDES permit for runoff?+
In most jurisdictions, yes. The Clean Water Act (Section 402) prohibits discharge of pollutants to waters of the U.S. without an NPDES permit. Most municipal MS4 permits explicitly list wash-water with detergents or bleach as a prohibited discharge to storm drains. Commercial operators and companies washing impervious surfaces often fall under MSGP requirements.
How do I calculate how many gallons of runoff my job creates?+
Runoff volume depends on water applied (GPM × minutes × area), surface absorption (impervious = ~90% runoff vs pervious = ~15%), slope, and proximity to storm drains. This calculator uses those variables plus your chemistry type to estimate total runoff and required capture percentage in real-time.
What's the difference between GREEN, YELLOW, and RED risk class?+
GREEN (rinse-safe) — low chemistry, distant drain, absorbent surface. Standard rinse-to-grade acceptable; documentation still recommended.
YELLOW (capture recommended) — elevated volume or moderate chemistry. Berm or filter sock required; log in your post-activity report.
RED (mandatory capture + manifest) — high SH, acid/degreaser, proximity to drain, or large impervious area. Wet-vac or reclaim mat required; digital manifest must be filed.
What fines can I face for runoff violations?+
Fines under 40 CFR 122.41 run $2,500–$25,000 per day per violation. State statutes add separate civil penalties. Repeat violations can trigger permit revocation and personal liability. CA, WA, and TX have particularly aggressive enforcement programs against commercial cleaning contractors. Use the EPA Fine Calculator to model your dollar exposure.
What capture methods are NPDES-compliant for pressure washing?+
Common NPDES-compliant methods: Vacuum recovery systems (best for large areas, 95%+ capture), berms + filter sock (perimeter containment + downstream filtration), reclaim mats (direct runoff to wet-vac pickup), catch-basin inserts (passive filtration for YELLOW-class jobs). This calculator recommends the right method for your inputs.
Does a Post-Activity Report (PAR) satisfy NPDES documentation requirements?+
A SurfaceOps Certified PAR documents GPS coordinates, timestamps, before/after photos, chemistry used, and runoff notes — creating an unalterable per-job compliance record. While not a permit replacement, it provides the documentation baseline regulators and property managers request when investigating complaints, and satisfies most contractual compliance requirements for commercial accounts.