Inflow and Infiltration Investigations

Infiltration and inflow (I/I) is excess water that flows into sewer pipes from groundwater and stormwater.

Groundwater (infiltration) seeps into sewer pipes through holes, cracks, joint failures, and faulty connections.  

Stormwater (inflow) rapidly flows into sewers via roof drain downspouts, foundation drains, storm drain cross-connections, and through holes in manhole covers.

Most I/I is caused by aging infrastructure that needs maintenance or replacement.

2022 Inflow & Infiltration Investigations are Ongoing - Updated on April 8, 2022

Manhole inspections

Year 11 of the Town's ongoing 12 year inflow and infiltration investigations project started on April 5, 2022 and work is ongoing.  There are three main components to this program: 

  1. Manhole inspections which includes opening manholes, conducting visual inspections, taking measurements, and recording all of the data. This information is later used to conduct repairs and improvements to manholes. This work is usually conducted between 7:00 AM and 5:00PM.
  2. Daytime cleaning and television of sewer pipelines and inspection on sewer manhole are typically conducted between 7:00 AM and 5:00 PM. During these routine inspections, the sewer pipelines are cleaned hydraulically with a pressurized water truck and a sewer-jetting nozzle and television inspected with a closed-circuit television inspection (CCTV) camera. The vacuum pressure created by the cleaning may cause air to escape though the traps and drains of your plumbing fixtures such as toilets and sinks.
  3. Nighttime flow measurements are taken by accessing, isolating, and monitoring sewer manholes to determine the amount of ground water entering the sewer system. These should not be any interruption in sewer service while these measurements are collected. This work is typically conducted between 11:00 PM and 6:00 AM

On Tuesday, April 5, 2022, the Town's consultants, Weston & Sampson Engineers, will began the daytime manhole inspections in subareas 3A and 3E. This work will be ongoing for the next few weeks.

On Sunday, April 10, 2022, the Town's sewer system consultants, Weston & Sampson, and contractor, National Water Main Cleaning Company, will be starting the nighttime flow isolation work in subareas 3A and 3E. This work will be ongoing for the next few weeks. 

The daytime cleaning and television inspections will be scheduled later this month.

Where & When

This project will be ongoing for the next month and work will take place in the following areas:

Subarea 3D – Rawson Hill Drive/ Deerfield Road and Colonial Drive/Bridle Path areas. Click here for a map.

Subarea 6C – South Quinsigamond (between Florence Street and Grace Avenue), Oak Street (between Tanager Drive and S. Quinsigamond), and Worthington Avenue areas. Click here for a map.

Subarea 3A & 3E – Hill Street, Mercury Drive/Neptune Drive, and Prospect Street at Fox Hill Road areas. Click here for a map.

Please Note

We apologize for any inconvenience you may experience during this work and appreciate your continued cooperation while we strive to improve our sanitary sewer system. If you have any questions or experience any inconvenience related to the inspection work described above, please contact the Department of Public Works - Water and Sewer Division at (508) 841-8502 or