Water & Sewer


The Division's responsibilities include:

Water System

  • Delivering safe drinking water to all residents and businesses in Watertown. 
  • Properly maintaining and testing to insure that drinking water meets all of the strict standards established by state and federal regulations.
  • Repairing of water main breaks and water service leaks.
  • Inspecting, maintaining, and replacing over 1,000 fire hydrants and adding new hydrants and gate valves to the system

Sewer System

  • Cleaning, inspecting and maintaining the sewer system to ensure it is in a state of good repair.
  • Responding to house line sewer backups and main line backups.

Drainage and Stormwater System

  • Cleaning, inspecting and maintaining the drainage system to ensure it is in a state of good repair.
  • Cleaning over 3,600 catch basins annually.
  • Repairing catch basin grates.

System Piping and Statistics

The Water Division serves over 9,200 users with an average supply of over 2.6 million gallons of water every day. Water is supplied by the Massachusetts Water Resources Authority. The Town has around 80 miles of water piping running under its streets. The water mains measure from 6 inches to 16 inches in diameter.

Sewage in the Town is all gravity fed--there are no sewage pumps stations in Town. Sewage is discharged to the Massachusetts Water Resources Authority sewerage system for treatment at Deer Island Wastewater Treatment Plant.  The sewer mains measure from 6 inches to 24 inches in diameter.

Water and Sewer Billing

The Water and Sewer Division issues bills quarterly, four annual bills per account.

Fiscal Year 2021 Water & Sewer Rates

Water System Cross-connection and Backflow Prevention

A cross connection is a connection between a potable drinking water pipe and a non-potable source. For example: you’re planning to spray weed killer on your lawn. You hook up your hose to the faucet on your house and to the sprayer containing the weed killer. If the water pressure drops at the same time you turn on the hose, the pressure change may cause the chemical in the sprayer to be sucked back into your home’s plumbing system through the hose. This is called backflow and could contaminate the water in your home system. 

Water utilities deal with this issue on a much larger scale – imagine if your hose were connect to a fire hydrant or a public access faucet (e.g. a campground), then the weed killer would be sucked into the public water supply.

View our flyer to learn ways to prevent cross-connection and backflow at your home.

The Massachusetts Plumbing Code (248 CMR 10.00) and the Massachusetts Drinking Water Regulations (310 CMR 22.22) both require installation of backflow preventers at all cross connections. Commercial entities must submit an application for approval of backflow devices by DPW.

View our flyer for additional information.

The Division continues inspection of commercial backflow prevention devices in compliance with DEP requirements.  

Leak Detection Program

Each fall, the Division inspects the water system for leaks. This entails placing microphones on fire hydrants to listen for leaks in the system.  Canvas “out of service” bags will be placed over hydrant during this process, this is only to protect the microphone.  All hydrants will be in service if needed.

Sanitary Sewer System Backflow Devices

All existing or new building drains from plumbing fixtures liable to backflow from a Department of Public Works (DPW) sewer, or a private sewer connected to DPW sewer, shall be required to have backwater valves installed at the owner’s expense. Any plumbing fixtures located at an elevation below the top of the manhole on the DPW sewer serving the fixture shall be considered to be liable to backflow. 

Learn how you can prevent sewer backups on you property.


The Division also meets the ever increasing reporting requirements of the EPA, DEP and MWRA for drinking water. Annually, the staff performs the six-week program of hydrant and water main flushing (Watertown has nearly 1,000 hydrants and 3,600 catch basins) and conducts weekly drinking water quality sampling, entailing more than 520 samples over the course of the year. The Division inspects and samples river outfalls for quality of the Charles River and continues our program for television inspection of sewer and drain lines, and conducts two annual rounds of sampling for lead in the drinking water.