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NPDES · BMP Planning
How much contaminated runoff does your job produce?
Enter surface type, chemistry, application method, and recovery method — get contaminated runoff gallons, NPDES exposure flag, and a site-specific BMP checklist in seconds. Download the worksheet PDF for your compliance file.
5 surface types
7 chemistry profiles
5 recovery methods
NPDES GREEN / YELLOW / RED
BMP checklist
PAR upsell on flag
Frequently Asked Questions
What is a runoff volume calculator for pressure washing?
A runoff volume calculator estimates how many gallons of contaminated water a pressure washing job will produce, based on surface area, chemistry used, application method, and surface type. The output includes an NPDES exposure flag (GREEN, YELLOW, or RED) and a site-specific BMP checklist to document your containment measures before you start.
What is an NPDES flag for pressure washing runoff?
NPDES (National Pollutant Discharge Elimination System) is the federal permit program that governs pollutant discharge to storm drains and waterways. The calculator's GREEN/YELLOW/RED flag classifies your job by discharge risk. RED means mandatory containment. YELLOW means capture is strongly recommended. GREEN means standard rinse-to-grade practices are likely compliant — but document it regardless.
How does recovery method affect the runoff flag?
Recovery method is the largest variable in the calculation. No containment means 100% of contaminated runoff reaches grade. Vacuum recovery captures 90%+ and can reduce a RED-flag job to YELLOW. Full containment (reclaim mat + wet-vac + sanitary discharge) eliminates nearly all NPDES exposure. Run the calculator with "No Containment" first to see your baseline risk, then select your recovery method to see the improvement.
Does this calculator replace a Certified PAR?
No. This calculator is a pre-job planning tool — it tells you what BMPs to deploy before you start and quantifies your runoff risk. A Certified Post-Activity Report (PAR) is the post-job documentation record that verifies what you actually did: GPS location, photos, chemical log, crew sign-off. For YELLOW and RED flag jobs, a PAR is the documentation that protects you if a complaint or inspection occurs.
What BMPs are most effective for pressure washing runoff?
Effectiveness varies by job. Vacuum recovery (wet-vac or reclaim mat) is the most reliable — 90%+ capture, works on any surface. Berms + filter socks work well for smaller flatwork jobs with low-chemistry runoff. Catch basin inserts are good supplemental measures but don't contain dissolved SH effectively. For acid/degreaser jobs, berms are mandatory and neutralization before discharge is required in most jurisdictions.