Only 3% of the water on Earth is freshwater. Of that 3%, only 1% is available as drinking water. The other 2% is frozen in polar ice caps.
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.