Does Stormwater Go Into the Sewer?

Stormwater Management Experts Explain the Process

When a storm rolls through the region, it can dump a significant amount of water in a short amount of time. As this stormwater flows across roads, rooftops, and other surfaces, many people wonder: Where does all that water go?

The answer depends on your location and the type of infrastructure in place. At iSTORMWATER, we’re here to help commercial property owners, managers, and contractors in Maryland, Virginia, Washington, DC, and Delaware understand the critical systems that manage stormwater – and what you can do to stay compliant and sustainable.

📞 Call iSTORMWATER at (410) 231-3455 to speak with a stormwater expert in the DMV area.

Where Does Stormwater Go?

Unlike wastewater from toilets, sinks, or showers – which is collected and treated at a wastewater treatment plant – stormwater runoff often flows into a separate system known as the storm sewer system. In most cases, this water is not treated before being discharged into local water bodies like rivers, lakes, streams, or catch basins.

These outfalls can carry pollutants directly into the environment, which is why stormwater management is so important. Common pollutants in stormwater runoff include:

• Motor oil and gasoline
• Fertilizers and pesticides
• Pet waste
• Sediment and debris
• Heavy metals and trash

What Is a Catch Basin?

A catch basin is an underground drainage structure designed to collect surface runoff and trap debris, sediment, and pollutants before they enter local waterways. Some catch basins are outfitted with stormwater filtration systems (like Contech StormFilters or media filters) that remove contaminants such as hydrocarbons, nutrients, and suspended solids.

Without effective stormwater management, these pollutants can harm:

• Fish and aquatic life
• Drinking water supplies
• Wetlands and ecosystems
• Public health and recreation areas

Stormwater vs. Wastewater: What’s the Difference?

It’s important to understand the distinction between stormwater and wastewater: