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Combined Sewer Overflow Information

If a Sanitary Sewer Overflow occurs on your property or you observe one in the street, immediately report it to the Water and Sewer Department at (781) 393-2403. Calls can be received 7 days a week, 24 hours a day. Thank you!

What are Sanitary Sewer Overflows (SSOs)?

A sanitary sewer overflow can spill raw sewage into basements or out of manholes and onto our streets, playgrounds, and into streams, before it can reach a treatment facility.

Why are they a problem?

Any overflow of the sanitary sewer including residential sewer backups or overflows from manholes in the street pose a serious public health risk. SSOs damage property and the environment, and cleanup can be expensive for homeowners and the City. Additionally, when SSOs enter water bodies, they affect water quality. When bodies of water cannot be used for drinking water, fishing, or recreation, we experience an economic loss.

What Causes a Sewer Back-up?

Anything, which should not be in a sewer line, has the potential of causing a blockage. For

– Kitchen grease, disposable diapers, and sanitary napkins can accumulate and cause a blockage.
– Tree roots seeking moisture can grow through cracks in the lines, causing a blockage.
– Vandals have stopped up lines by putting bricks, wood, oil filters, bed springs, and even Christmas trees in manholes.
– Illegal hookups allow excess water into the lines. Outside stairwell drains, sump pumps, roof leaders, and drain gutters should never be connected to the sewer system. A sewer system is designed to carry a predetermined amount of sewage.
– Rain water not only overloads the system, but also raises the cost of the treatment process.

What Can I Do to Prevent Back-ups?

To protect your property follow these simple Do’s and Don’ts.

DON’T Put diapers or sanitary napkins in the toilet
DON’T Dispose of grease down the drain
DON’T Plant trees near sewer lines DON’T Connect any drains or sump pumps to the sewer system
– DO Install a plumbers test plug (available at hardware stores) at the lowest floor drain in your home
– DO Hire a plumber to install a back flow valve on the lowest drain line. Regularly inspect and maintain the valve
– DO Modify the plumbing line so that water is pumped to an upper level drain, eliminating the drains at the lower level

Just in Case

– Locate and keep accessible the sewer clean out in your front yard. If you do not have a clean out, have one installed by a plumber. The clean out is the property owner’s responsibility
– Check your homeowners insurance policy. If you are not covered for back-ups, call your agent for information on costs and coverage options
– If you experience a back-up, save all receipts related to any repair, cleaning, or damages

Report Illegal Dumping


Most catch basins connect to storm drains that discharge the runoff, without treatment, to the nearest water body. The dumping of any material such as motor oil, paint, leaves, yard clippings, pet waste, sand, etc. into a catch basin can pollute the waterways and is illegal.

If you observe someone dumping into a catch basin, immediately report it to the Police Department at (781) 391-6404. Calls can be received 7 days a week, 24 hours a day. Thank you!