The plan's complex funding formula would raise rates somewhat but also attract grants and encourage private investment.
Further, the Water Department says the city's greening would result in more jobs, higher property values, better air quality, less energy use, and even fewer deaths - from excess heat.
The plan is a radical departure from the highly engineered tunnels and sewage plant expansions cities have traditionally opted for.
"This is the most significant use of green infrastructure I've seen in the country, the largest scale I've seen," said Jon Capacasa, regional director of water protection for the Environmental Protection Agency, which has the final say on whether the plan passes muster.
"We commend Philadelphia for breaking the ice," he said.
Whether the plan will work as the department intends is still being analyzed by regulators and environmental experts. (This will take a while. The printed plan is 3,369 pages.)
Theoretically, it's workable, said the Natural Resources Defense Council's water expert, Nancy Stoner. The green techniques "are well-demonstrated," she said. "It's the scaling up that's new. That's what's really exciting."
Others concur - mostly.
"I believe it's the most significant investment in transforming the city that we'll see in our lifetimes," said Patrick Starr, senior vice president of the Pennsylvania Environmental Council. "It will change the way neighborhoods look, the way many streets and blocks look."
Either way, cities big and small are watching to see whether Philadelphia can get the plan approved by the EPA and, if so, deliver on its promise.
"This has national implications," said Christine Knapp, outreach director with the state environmental nonprofit PennFuture.
Here's the trouble with storm water: 60 percent of the city has a combined sewer system, which means both runoff from streets and wastewater from bathrooms and kitchens flow through the same pipes.
