What's Allowed to go in a Storm Drain?

What's Allowed to go in a Storm Drain?

In most communities, storm drains lead to separate storm sewers that are only meant to carry relatively clean rainwater and snow melt. Separate storm sewers carry the water directly to nearby streams, rivers, and other water bodies without any treatment. This is different from the rarer combined sewer systems, where stormwater and sanitary wastes get treatment together before being released. These older combined systems usually struggle to contain the large volumes of modern-day stormwater and also release untreated water during larger storms.

In Pennsylvania, there are approximately 125 combined sewer systems and over 1000 regulated separate storm sewer systems, known as MS4s. There are also countless additional separate systems that are in unregulated areas around the state.

Storm sewer systems aren't just underground pipes. They include various drains and ditches, and concrete channels along roads and parking areas meant to carry water away from these surfaces. Anything that is not permitted to go into a separate storm sewer is known as an illicit discharge. They are illicit because these sewers are not designed to receive and treat contaminated water before releasing it back to the environment. Examples of things that end up in storm sewers illicitly are septic wastewater, carwash wastewater, auto fluids like used oil and radiator flushing, laundry drain water, household toxics, and chemicals, leaking waste containers, pool and hot tub water, and even garbage, grass clippings, and pet waste.

Sometimes these things end up in storm sewers intentionally, from someone dumping or pouring wastes into drains directly or through hoses. But illicit discharges often come from accidents and spills, and even from hidden leaks. Many communities are required to have ordinances to prohibit these discharges and enforce against them, no matter the source. This is because illicit discharges all result in high levels of pollution including heavy metals, toxics, oil & grease, viruses & bacteria, and sometimes unknown agents that degrade water quality and water supplies.

Ultimately, illicit discharges such as these threaten human health and wildlife. As a community member, you can help protect water quality. The most important thing is to not use storm drains and ditches as waste receptacles.  This means keeping drains free of yard debris, and not pouring or dumping wastes directly into these drains or into streets, driveways, and lots that will ultimately wash into drains during the next rain. You should also use proper waste containers with lids to store your trash and participate in your community garbage pick-up service or haul your garbage to a proper drop-off location. You can also wash your car over grass instead of in the street, properly maintain your septic system, clean up after windblown trash cans, drain your pool water to a vegetated area where it can soak into the ground instead of draining to the storm sewer system, properly dispose of pet waste, and maintain your car to prevent leaks.

If you have an accidental spill, do your best to safely clean it up and dispose of it. Contact your municipality if it's too big for you to handle. They likely have a spill response plan and team.

Remember, a storm sewer is not a trash can or a sink drain. It's a direct pathway to your local creeks and rivers and only meant to carry clean water!

If you have more questions about storm drains or stormwater in your community, or you are interested in learning more, you can find a full series and articles and videos in the Penn State Extension Stormwater Basics series.