Most of Jersey City is serviced by a combined sewer system. In a combined sewer system, water runoff from sidewalks, streets, parking lots, and buildings flows into storm drains (also known as catch basins) and combines with sanitary sewers from buildings, which then flows to a water treatment facility.

During events that produce large amounts of water runoff (such as heavy rain or snow melts), the volume of the runoff flowing into the sewer is greater than the capacity of the pipe to the treatment facility. When this occurs, the contaminated and polluted excess wastewater and runoff combined in sewers discharge directly into surrounding waterways. This is called a combined sewer overflow.

In a separated sewer system, water runoff flows into a storm sewer and is discharged into neighboring waterways, whereas wastewater flows into a separate sanitary sewer and is sent to a treatment plant. Because these systems are separate, weather events do not cause wastewater to flow into waterways.

Under the terms of the Clean Water Act, combined sewer systems are regulated by the EPA and municipalities are responsible for devising strategies to reduce or eliminate combined sewer overflows and mitigate the resulting pollution of waterways. Strategies for accomplishing this goal include two types of solutions: grey infrastructure, which can be creating a separated sewer system, building facilities to treat or filter outfall discharges, and underground detention or retention infrastructure to hold excess runoff and wastewater; and green infrastructure, which captures, absorbs, or diverts storm water before it enters sewer systems. Green infrastructure includes tree pits, bioswales, rain gardens, and other features which incorporate vegetation or mimic nature. Read more about green infrastructure on our Green Infrastructure Page.


Click here to view an interactive map that provides the location of, and information on, the 212 Combined Sewer Overflow outfalls in New Jersey. These outfalls are located in a total of 21 municipalities.