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Stormwater Systems

stormwater outfall
Stormwater Outfall at Metropolitan Ave. Hyde Park

Boston Water and Sewer Commission (BWSC) owns and operates a system for the collection and transport of stormwater in the City of Boston. The system serves approximately 20,500 acres, 75% of the total land area of Boston. The remaining 25% is comprised of parks, cemeteries and undeveloped land.

The Stormwater System

The stormwater system is a separate system that collects water from storm water runoff (rain and snow melt) and discharges it into receiving waters around Boston. BWSC controls most of the this system, however, some storm drains and outfalls are privately owned or are owned by agencies such as the Massachusetts Highway Department, the Massachusetts Turnpike Authority, Massport and the Department of Conservation and Recreation.

Approximately 75 percent of Boston is served by separate storm drains. The remainder of Boston is served by combined sewers, sanitary sewers only or is open space with no sewers or drains.


The Infrastructure

Traditional stormwater infrastructure is used in most of Boston to capture runoff from rain or snow events via 35,934 catch basins on the streets and sidewalks of the city. Stormwater runoff is transported through almost 600 miles of drain pipe and carried to one of the 393 stormwater outfalls where it discharged into one of the water bodies surrounding Boston. The majority of the runoff in Boston is discharged directly into the Charles River or Boston Harbor with no filtration or treatment.

The majority of the stormdrain pipe infrastructure in Boston is made from polyvinyl chloride (PVC), reinforced concrete pipe (RCP), and ductile iron. There are also still brick and clay storm drains within the city, though they are no longer constructed today. This traditional infrastructure, also known as grey infrastructure, services most of the city's stormwater drainage needs. In recent years, new types of infrastructure have been used to manage stormwater in various areas of the city. These systems, often known as stormwater best management practices or green infrastructure, can also be made from high density polyethylene (HDPE) or smooth lined corrugated plastic piping. More about the requirements for stormdrain material can be found on the Materials Requirements form on the Regulations page of the BWSC website.

Green Infrastructure/Low Impact Development (GI/LID)

Green infrastructure/Low Impact Development (GI/LID) is the use of stormwater management practices that focus on infiltration and treatment of stormwater rather than the pipe and discharge practice currently in use across most of the United States. GI/LID projects create more environmental friendly buildings, homes, and parking areas.