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City of Philadelphia

Stormwater Management

What is stormwater?
In a natural, undeveloped environment, rain falls on the ground and evaporates or is absorbed into the soil. In an urban, developed environment such as Philadelphia, rain falls on the ground, "runs off" and flows into the sewer system. This water is referred to as stormwater or stormwater runoff.
Why do we need to manage stormwater?
Stormwater runoff has been identified as the number one cause of pollution to rivers and streams, the source of our drinking water.

When it rains or snows, stormwater runoff: 
  • contributes to combined sewer overflows
  • pollutes our rivers with fertilizers, oil and sediment
  • destroys valuable aquatic and riparian habitat
  • floods homes and businesses

PWD manages stormwater by building and maintaining public stormwater infrastructure and by regulating private development in the city.

Green City, Clean Waters
Green City, Clean Waters, Philadelphia’s plan to reduce combined sewer overflows, calls for an investment of $2.4 billion over the next 25 years in public infrastructure. This money will fund treatment plant upgrades and the installation of green stormwater infrastructure in streets, parks, schools and other public spaces. The plan also encourages the private sector to use green stormwater infrastructure.