Infographic_Stormwater Flow_September 2022

What is stormWater?

Have you ever wondered where all the water goes when it rains or after the snow melts? Some of it seeps into the ground or evaporates, but much of it runs off over the land, down streets and into a storm drainage system. This runoff water is called stormwater.

System Overview

The Department of Public Works manages the City’s Municipal Separate Storm Sewer System (MS4). This system, also known as the drainage system, includes approximately:

  • 185 Miles of Drainage Pipe 
  • 8,000 Catch Basins/Storm Drains
  • 2,000 Drain Manholes
  • Saxonville Levee 
  • 500 outfalls

Anything that flows down a storm drain comes out in a nearby waterway. As stormwater flows over land, down streets, and into storm drains, it picks up pollutants such as litter, grass clippings, leaves, lawn fertilizers, oil leaks from cars, winter sand and road salt, and pet waste. These pollutants can flow directly into our waterways.

What is the difference betweenstormwater and wastewater?

Stormwater is rainwater or snowmelt that runs off roadways, lawns, and other impervious surfaces.

Sewage/wastewater is a combination of the liquid and water-carried wastes produced by people, residences, commercial buildings, industrial facilities, and institutions. Sewage is collected and transported to the Massachusetts Water Resources Authority's Deer Island Wastewater Treatment Facility.

Unlike wastewater, stormwater does not go to a treatment facility but rather ultimately flows into our streams, rivers, lakes, and ponds.