Case Study

Smart Cities Tech

Philadelphia: Stormwater Credits Explorer


High-tech on-line calculator allows private developers to select most cost-effective green infrastructure.

Stormwater Credits Explorer offers large-lot owners the opportunity to calculate which green infrastructure to install and choose which costs less or does more.


Northern humid subtropical zone. Summers are typically hot and muggy, fall and spring are generally mild, and winter is cold.


White 42%
Black or African-American 44%
Hispanic 12%
Asian 6%

In 2015, Philadelphia Water launched the Stormwater Credits Explorer application that enables large-lot owners to calculate their savings in stormwater fees by installing different types of green infrastructure.

Using a browser-based platform, owners of commercial and industrial properties in Philadelphia can “draw” ideas for green infrastructure projects directly onto a bird’s-eye-view map of their lot.

Like many cities, Philadelphia’s stormwater utility levies non-residential stormwater management fees depending upon the percentage of impermeable surface on the lot. Focused solely on stormwater credits, but similar to other calculators, Credits Explorer pre-loads localized data, allows the owner to pinpoint their property and then try different green infrastructure solutions. The program not only calculates the impact on surface permeability; it calculates the amount owners can save each month on stormwater fees.

Unlike other calculators, Credits Explorer doesn’t require much data input; it’s already in the system.

Lessons Learned

Simple, do-it-yourself calculators encourage owners to seek cost-effective stormwater solutions.

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