Reducing Stormwater Pollution

Across approximately 25 percent of Pittsburgh, sewage and stormwater are routed into separate underground sewer pipes. The sanitary sewer pipes carry sewage to the Allegheny County Sanitary Authority (ALCOSAN) wastewater treatment plant. When it rains, the storm sewer pipes send the stormwater directly to our streams and rivers. 

Unfortunately, that stormwater picks up litter, oil, road salt, and other pollutants on the ground before flowing through storm drains to our streams and rivers. This pollution harms local water quality, fish and wildlife, and recreation. 

Two diagrams side by side, the left one showing the separate storm sewer system without rainwater during dry weather, and the other showing the separate storm sewer system carrying rainwater to the river during wet weather.

Federal and state law help protect and restore rivers and streams by regulating this stormwater pollution. The City of Pittsburgh and PWSA have a Municipal Separate Storm Sewer System (MS4) permit from the Pennsylvania Department of Environmental Protection (DEP). This permit requires that we follow specific guidelines and implement practices to reduce pollutants from our separate storm sewer system. 

To meet these water quality goals, the City and PWSA are strengthening our partnership and expanding our existing stormwater management program. We are constructing infrastructure projects that capture and filter polluted stormwater, such as the Volunteers Field Rain Garden Project, and reduce sediment, such as the Saw Mill Run Stream Restoration Project

Help Reduce Stormwater Pollution

A little bit of litter on the street might not seem like a big deal, but everyone’s pollution adds up. We all can take simple actions every day to help protect our streams and rivers and keep our neighborhoods clean. Together, these small positive actions can make a big difference! 

Actions You Can Take

Everyday Actions

Close-up photo of a person with gloves on picking up plastic bottles and other litter from grass and putting it into a trash bag
  • Don't litter and do pick up litter if you can do so safely. Dispose of trash and recycling properly so that it doesn't clog our storm drains, pollute our rivers, and harm fish and wildlife. 
  • Pick up and dispose of pet waste properly in trash cans, since it can make humans sick and causes water pollution. 
  • Stop any oil leaks from your car immediately, since even a little bit of oil can pollute a lot of water.
  • Do not over-apply road salt and pesticides, since any excess gets washed away into our streams and rivers, harming fish and wildlife.
  • Clean up any grass clippings or leaves that might get washed away in a rainstorm and pollute streams and rivers. 
  • Make sure bare soil is covered so that it doesn't wash away and smother fish and wildlife in streams and rivers. 

Help Care for Storm Drains

Close-up photo of a storm drain with rain entering and a curb marker next to it that says "drains to drinking water, please don't dump"

Did you know that we have more than 25,000 storm drains in Pittsburgh that lead to our sewer system, streams, and rivers? You can help reduce river pollution and street flooding by keeping storm drains clear of trash and debris.

  • Never dump vehicle fluids, grass clippings, leaves, or litter into storm drains, since that leads to pollution in our streams and rivers and clogs in our sewer system. 
  • Where safe to do so, clear leaves, litter, and other debris off of storm drain grates and dispose of them properly in the trash.
  • Never reach inside a storm drain or lift the grate.
  • If you see a clogged or broken storm drain, please call our 24/7 Dispatch at 412-255-2423 (Press 1), contact us @pgh2o on Twitter, or fill out our Report an Issue webform so that we can send a crew out. 

You can also sign up with Allegheny CleanWays to adopt a storm drain in your neighborhood! Register to be a GrateKeeper at and they’ll provide the information you need to get started.

Wash Your Car Properly

A car going through a carwash

Washing your car in a driveway, parking lot, or street causes all the soap, dirt, salt, oil, and grease to flow into a storm drain and end up as pollution in our streams and rivers. 


  • Take your car to a commercial car wash, which is required to treat the dirty wash water and dispose of it properly.
  • Commercial car washes also use clean water more efficiently and recycle wash water when possible, reducing water waste.  
  • If you can’t take your car to a commercial car wash, make sure to only wash your car on grass or gravel, which helps soak up and filter the wash water before it gets to storm drains.
  • Wash with just water or a biodegradable, phosphate-free, water-based cleaner to reduce water pollution.
  • Instead of a hose, wash with a bucket and sponge to minimize your water usage.

Fertilize Sparingly

A fertilizer dispenser

Fertilizers may help your garden or lawn grow, but nitrogen and phosphorus, nutrients found in fertilizers, can harm downstream water quality. When it rains, any fertilizer nutrients that haven’t been used by plants are washed away into our streams and rivers. These nutrients can cause excessive growth of algae and aquatic weeds. Algae reduce the amount of oxygen in the water, which kills fish and aquatic wildlife.


  • Only fertilize if necessary and do not overapply.
  • Use a soil test to measure existing nutrient levels.
  • If your soil phosphorus levels are adequate, select a phosphorus-free fertilizer.
  • Select slow-release and organic fertilizers, which are less likely to wash away.
  • Spread grass clippings over your lawn to provide needed nitrogen to soil.
  • Fertilize lawns in the fall to promote root growth and prevent nutrients from washing away during spring rains.
Find Your Sewershed

Learn more about the separated or combined sewer area that you live in using our Find Your Sewershed webmap.