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Sanitary Sewer Overflows (SSOs)
Overview
A sanitary sewer overflow (SSO) is an unintentional discharge, spill, or release of untreated sewage into the environment or a property. SSOs are also known as sewer backups and the resulting flooding can cause damage to a property and pollute the environment.
SSOs or Sewer backups can be caused by:
- A blocked or collapsed private sewer lateral
- Improper disposal of grease that creates blockages in sewer lines or internal plumbing
- Obstructions or breaks in the sewer lines or in internal plumbing
- Improper disposal of other items, such as baby wipes or rags, that blocks sewer lines or internal plumbing
- Unusually heavy rainfall, which can result in an inflow of stormwater into sewer lines
Raw sewage is dangerous, because it contains bacteria and other hazardous microorganisms. Touching or walking through contaminated areas can bring germs into uncontaminated areas of your home. Children and pets are especially vulnerable.
Effects of Sanitary Sewer Overflows:
SSOs can cause significant environmental and public health problems. SSOs that occur in streets can cause sewage to enter the storm drain system and travel to local waterways. This can pollute surface waters, endanger aquatic life, and interfere with the recreational uses of waterways and beaches. SSOs that occur within buildings can damage the property and its contents, which can result in financial costs for the property owner, and pose a significant health risk to residents of the property, especially children and pets.
State and federal regulations now require Boston Water and Sewer Commission and other sewer agencies to report SSOs in order to meet Clean Water Act requirements and to reduce the occurrence of SSOs across the BWSC system.
BWSC closely monitors sanitary sewer overflows that occur in Boston and maintains a Sanitary Sewer Overflows Map on the Maps page. The map and list identify recent SSO locations.