Water & Sewer
The City has completed its Public Water System Service Line Inventory and submitted it to Massachusetts Department of Environmental Protection (MassDEP) and the Environmental Protection Agency (EPA). As required, a copy of the submitted inventory is readily available for the public to review at the Department of Public Works DPW) headquarters located at 124 Orchard Street. Please request access at the front desk during our operational hours from 7:30am through 3:30pm and a staff member will assist you.
Responsibilities
Water
The Water Division is responsible for over 80 miles of underground water mains ranging from 6”-16” in size, as well as water services to residential structures and commercial buildings. This Division also operates and maintains a radio frequency meter reading system as well as every individual water meter in all residential structures. They retrieve accurate water meter readings from commercial buildings where the City does not own the water meter. Additionally, the Water Division maintains approximately 995 fire hydrants and flushes the water system annually through these hydrants.
The Water Division operates numerous regulatory programs in accordance with Department of Environmental Protection regulations to ensure quality of water and to protect the potable water system. A synopsis of these programs is as follows:
- Backflow protection and inspection / device testing / commercial cross connection survey
- Weekly water sampling and inspection, including testing by the Division and by the MWRA analytical lab at various locations citywide
- Monitoring for lead and copper in the drinking water
- Annual Leak Detection Program to monitor for unaccounted water
- Inspection of all water/sewer/drain projects
Sewer
The Sewer Division is responsible for the operation and maintenance of approximately 78 miles of sewer line and approximately 8,000 residential sewer connections to the sanitary sewer system, as well as the maintenance and operation of approximately 80 miles of storm drain lines which vary in size from 6” in diameter to 72” in diameter as well as maintenance, rebuilding, cleaning of approximately 3,200 storm drains.
The Division works closely with the DEP, EPA and the MWRA in various aspects of regulatory compliance and system monitoring. The division monitors, as well as samples, numerous storm drain discharge points on a regular basis while also sampling and monitoring key junction manholes located within the interior of the storm drain system, as required by the EPA.
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 (MWRA). The City has about 80 miles of water pipes running under its streets. The water mains measure from 6"-16" in diameter.
Sewage in the City is all gravity fed—there are no sewage pumps stations in Watertown. 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"-24" in diameter.
Water and Sewer Billing
The Water and Sewer Division issues bills quarterly with four annual bills issued per account.
Fiscal Year 2026 Water & Sewer Rates (PDF)
Fiscal Year 2025 Water & Sewer Rates (PDF)
Fiscal Year 2024 Water & Sewer Rates (PDF)
Fiscal Year 2023 Water & Sewer Rates (PDF)
Fiscal Year 2022 Water & Sewer Rates (PDF)
Fiscal Year 2023 Water & Sewer Rates (PDF)
Watertown - Water and Sewer Rate Study - FINAL 2022 for Fiscal Year 2023
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, so 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 was connected 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 (PDF) 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 (PDF) for approval of backflow devices by DPW.
View our flyer (PDF) for additional information.
The Division continues inspection of commercial backflow prevention devices in compliance with DEP requirements.
Sanitary Sewer System Backflow Devices
All existing or new building drains from plumbing fixtures liable to backflow from a Department of Public Works sewer or a private sewer connected to DPW sewer are 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 are liable to backflow.
Learn how you can prevent sewer backups on your property (PDF).
Lead in Drinking Water Information
There is no known lead in the municipal water distribution system.
There are approximately 9,250 water services on record in the City. Review of City records indicate that there are no water services comprised completely of lead pipe. However, prior to standardizing on copper pipe, water services were often laid using iron pipe. To create a connection to the water main, short, angled pieces of lead pipe, typically about 2-feet in length, were used. We refer to these as “goosenecks.”
Each year, the City removes lead goosenecks as part of the annual road reconstruction projects, water system improvements, and incidental repairs due to service leaks. New development and significant redevelopment projects are also required to remove lead services associated with those projects.
Some homes, not just in Massachusetts and Watertown, have some lead or brass fittings containing lead in their internal plumbing systems. For these properties, stagnant water in plumbing fixtures should be flushed prior to use.
For more information, please visit the MWRA website for Lead in Tap Water. Call the Water Department at 617-972-6420 for information about your service.
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.
Home Water Leaks
Dripping faucets and showerheads can waste between 75 and several hundred gallons of water per week depending on the severity of the drip. Worn out washers, generally about 50 cents each, are the main cause of these leaks. Leaky toilets are another common issue and can waste up to 50 gallons of water per day. Often toilets just need a replacement flapper or flush value to stop the leak. While a leaky faucet is pretty obvious, hidden leaks in the toilet, under the sink, or behind a washing machine can waste a significant amount of water and can cause damage to your floors or ceilings. If you think you may have a leak in your home, take a reading of your water meter. Wait an hour, making sure no one uses any water in your home, and then check the meter again. If the reading has changed, you have at least one leak that you need to investigate. See the Unrepaired Leaks Can Be Costly flyer (PDF).
MWRA Water Conservation Brochure
MWRA How to Find and Fix Leaks
Reporting
The Division also meets reporting requirements of the Massachusetts Department of Environmental Protection (MassDEP), Environmental Protection Agency (EPA) and Massachusetts Water Resource Authority (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, testing more than 520 samples over the course of the year. The Division inspects and samples river outfalls for quality of the Charles River, conducts television inspection of sewer and drain lines, and conducts two annual rounds of sampling for lead in the drinking water.
October 2024: The City has completed its Public Water System Service Line Inventory and submitted it to MassDEP and EPA. As required, a copy of the submitted inventory is readily available for the public to review at the Department of Public Works DPW) headquarters located at 124 Orchard Street. Please request access at the front desk between 7:30am and 3:30pm and a staff member will assist you.
Hydrant Flushing Schedule
Hydrant Flushing Schedule Fall 2025 Week 6 (PDF)
Hydrant Flushing Schedule Fall 2025 Week 5 (PDF)
Hydrant Flushing Schedule Fall 2025 Week 4 (PDF)
Hydrant Flushing Schedule Fall 2025 Week 3 (PDF)
Hydrant Flushing Schedule Fall 2025 Week 2 (PDF)
Hydrant Flushing Schedule Fall 2025 Week 1 (PDF)
Valve Exercising Program
What is valve exercising and why is it necessary?
Valves are crucial components in municipal water systems, controlling water flow in our distribution mains. There are dozens of types of valves, but all have the same purpose: to control the flow of water, isolate sections of pipe for repairs, and ensure safe and efficient distribution. Valve exercising is the process of opening and closing valves to ensure they continue to function properly.
Over time, valves can seize or become stiff due to corrosion, mineral buildup or lack of use. Exercising helps break up any buildup and allows operators to inspect the valve for signs of decay or malfunction. The American Water Works Association (AWWA) defines the practice of valve exercising as; "[valves] should be operated through a full cycle and returned to its normal position on a schedule that is designed to prevent a buildup of tuberculation or other deposits that could render the valve inoperable or prevent a tight shut-off." The process prevents seizing, extends their lifespan, and allows the Water Division to identify potential damage before the valve malfunctions. It is also a quick and relatively easy way to ensure minimal disruption to the water distribution system.
Municipal valves found on hydrants, water lines, pipes and various other equipment need regular exercise to remain serviceable and to avoid unexpected failures. Following a regular valve exercise schedule can save the municipality time, energy, and money.
What might residents experience?
- Discolored Water: Exercising valves can stir up sediment in the pipes, leading to cloudy or rusty-looking water. This is usually harmless and clears up after running the cold water for a few minutes.
- Noise or Vibration: You might hear unusual sounds from your plumbing as valves are operated and water flow changes.
- Utility Crews in the Area: Expect to see workers and equipment near valve access points, often in the street or sidewalk. They may block off small sections for safety.
- Advance Notices: Notifications to residents ahead of time if valve exercising might affect water service.
- Temporary Water Disruptions: While we will do our absolute best to keep providing water, in the event of an emergency, water may be shut off.
The Water Division is hoping for a smooth rollout of the program. Should any questions arise, please call 617-972-6420 ext. 13119 and we will be happy to answer them.