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Did You Know?

Itís important to keep sidewalks in front of homes and businesses clear of ice and snow to avoid falls and injury. To avoid flood and traffic accidents, do not shovel snow from driveways and sidewalks into the street.

Sanitary Sewer Overflows

Boston Water and Sewer Commission maintains a vast system of sanitary sewers and stormwater drains designed to properly convey sanitary flows to the MWRA's Deer Island Treatment Facility and stormwater to receiving waters. Over the past two decades, the Commission has invested heavily in upgrading the system to increase capacity as well as separate combined sewers, resulting in far reaching environmental benefits. As the Commission's work progresses, BWSC carefully monitors Sanitary Sewer Overflows (SSOs). Some SSOs occur when wet weather events cause inflows to exceed the collection capacity of the system, producing an overflow of sanitary sewerage. SSOs can also occur during dry weather events due to a variety of causes, including blockages and structural failures. The map below displays the location of SSO events throughout the city based on a selected timeframe.


  1. Select the desired timeframe from the dropdown on the upper-right corner of the map. SSOs that occurred during that period will be indicated by caution symbols on the map.
  2. Click on a caution symbol to zoom to its street location. SSO details are displayed in the table below the map. Table columns can be sorted by clicking on their headings and widened by clicking and dragging on the borders.
  3. Click the Citywide button in the upper-right corner to return to a full view of the city.
  4. Click the plus and minus buttons in the upper-left to zoom in and out.
  5. Click the Export button to download the table in Excel format.
sso legend