Wastewater Collection

Lawrence’s wastewater collection system consists approximately of the following:

  •     137 miles of sanitary and combined sewers
  •     41 miles of storm drains
  •     4 wastewater pumping stations
  •     4,000 catch basins
  •     3,500 manholes


The sewers range from 4 inch pipelines to 8 foot arches. In the past, the sewers were generally constructed of vitrified clay, brick, and concrete. Newer sewer construction materials typically consist of PVC and reinforced concrete. The sanitary and combined sewers discharge into interceptors along the Merrimack River, where they are transported to the Greater Lawrence Sanitary District (GLSD), located in North Andover, for treatment.

While approximately 30% of the system contains separate sanitary and storm sewers, combined sewers serving both sanitary flow and stormwater drainage are prevalent in the older portions of the service area. Combined sewer overflows (CSOs) occur during certain storm events when the capacity of the combined sewer system is unable to convey the mixture of wastewater and stormwater to the treatment plant. There are presently 6 CSO outfalls listed in the National Pollutant Discharge Elimination System (NPDES) Permit issued by EPA to the GLSD.

Toilet (JPEG)

Watch What You Flush

When you use your toilet, shower, washing machine or dishwasher, waste water leaves your home through pipes that connect to the City's sewer system. Many materials frequently flushed or poured down the drain can harm the pipes that connect to City sewers as well as the City's sewer system.

Sewer Problems

Every property owner connected to the City's sewer system can be a potential contributor to sewer problems, and a potential victim of those problems. Putting the wrong things down the drain can damage the sewer system, cause sewer backups in your home, and sewer releases to the environment. Anyone who uses the City's sewer system should be responsible for what they flush or pour down drains.

Don’t Flush This 

Basically, the only thing you should ever flush down a toilet is human waste (urine and feces) and toilet paper. Here is a list of some of things to keep out of the toilet:

  • Bandages and bandage wrappings
  • Cleaning wipes of any kind
  • Condoms
  • Cotton balls and swabs
  • Disposable diapers
  • Facial tissue
  • Mini or maxi pads
  • Tampons
  • Unused medications (put original containers in a plastic, zip-lock bag and throw the bag in the trash)
Grease in Pipe (JPEG)

Fats, Oils, & Grease (FOG)

Grease is a byproduct of cooking. It comes from meat, lard, oil, shortening, butter, margarine, food scraps, baking goods, sauces and dairy products. Grease in sewer pipes causes sewer maintenance problems for property owners and the City. Never pour grease in your sink drain and try to use your garbage disposal less. 

Grease in Pipes

When grease washes down the sink, it sticks to the insides of the pipes that connect your home or business to the City‘s sewer. It also coats the insides of the City’s sewer pipes. Eventually, the grease can build up until it completely blocks sewer pipes. That can create difficult and expensive maintenance problems for both the City and private property owners. Blocked sewer pipes can cause raw sewage to back up into your home or business, or overflow into streets and streams. Garbage disposals don’t keep grease out of sewer pipes. Products that claim to dissolve grease may dislodge a blockage, but will only cause problems farther on down the line when the grease hardens again. Learn more about FOG.

Sewer Overflow (JPEG)

Sanitary Sewer Overflows (SSOs)

Sanitary Sewer Overflows (SSOs) are a condition in which untreated sewage is released from the sewer system prior to reaching the wastewater treatment plant. SSOs are primarily caused by pipe collapses, grease deposits, and debris blockages. SSOs can be recognized as water discharging from sewer manholes and/or catch basins, into basements, etc. Sewage odors may also be present. SSOs are an environmental and public health concern and it is crucial that SSOs are reported to the proper authorities so that the issue can be addressed, and the area can be decontaminated.

Reporting SSO

In the case that you witness what you think is an SSO, please reach out to the City's Water and Sewer Department immediately at 978-620-3580 or 978-620-3321.