Finance category
Mortgage, loan, investing, tax, and money calculators.
Stormwater Credit Revenue Calculator
Cities charge stormwater fees; green infrastructure earns credits to offset.
Annual fee savings
$425
Payback years
423.5
Lifetime value
$10,625
How the math works
Fee = (sqft / 100) × $/100sqft. Savings = fee × credit %.
(20k / 100) × $2.50 × 85% = $425/yr. $180k / $425 = way too long. Check credit eligibility.
How to Use
- Enter impervious sqft reduced.
- Enter fee per sqft.
- Enter credit % eligibility.
- Enter infrastructure capex.
- Enter life years.
- Read annual savings and payback.
Frequently Asked Questions
Stormwater fees?
Most US cities with EPA MS4 (Municipal Separate Storm Sewer System) permits charge fees based on impervious surface area. Common fees: $0.50-5/100 sqft impervious/year. Commercial large parcels: $2,000-30,000+/year stormwater fees. Residential: bundled into property tax typically. New fees being adopted annually. Philadelphia: stormwater fee avg $10/mo residential, $100-5,000/mo commercial.
Credit mechanisms?
(1) Green roof: 40-100% credit on roof sqft area. (2) Pervious pavement: 80-100% credit vs asphalt. (3) Rain gardens, bioswales: 80-100% credit on drainage area. (4) Detention ponds: 100% credit on captured area. (5) Rainwater harvesting/cisterns: credit based on stored volume. Stacked credits can reduce fees 50-90%.
Top-paying cities?
Philadelphia (Pa): rewards program $0.32-0.80/sqft/year. Washington DC: RiverSmart Rewards. Portland OR: Clean River Rewards 35-100% discount. Seattle: RainWise program. Chicago: impervious surface credits. NYC: pending Waterkeeper credit program. Boston, Baltimore, Atlanta, Denver: active credit programs. Credits typically cover 10-40% of project payback through fee savings alone.
Application process?
Engineering report: certified by PE (Professional Engineer) documenting credit-eligible features. Drawings, calculations, maintenance plan. Municipal review: 2-6 months typical. Annual certification: some cities require annual reporting on system condition. Credit lifespan: permanent if system maintained. Credit trading: some cities allow transferring credits between properties (emerging).
Related Calculators
More Finance Calculators
Browse all finance →AI Cost Calculator
Compare token costs across OpenAI, Anthropic, and Google AI models. Calculate monthly API spending for GPT-4o, Claude, Gemini, and more.
Tip Calculator
Calculate the perfect tip and split the bill between friends. Choose preset percentages or enter a custom tip amount.
Bill Splitter Calculator
Split an uneven restaurant bill by item, divide tax and tip proportionally, and see exactly who owes whom.
Discount Calculator
Calculate sale price, discount amount, stacked discounts, sales tax, and total savings for any markdown.
Gas Mileage Calculator
Calculate MPG or km/L, estimate trip fuel cost, and compare annual fuel expenses between two vehicles.
Sales Tax Calculator
Add sales tax to a price, reverse-calculate the pre-tax amount from a total, and estimate tax for multiple items on one receipt.
Keep exploring