Uni-directional Flushing (UDF)

Uni-directional Flushing (UDF)

Uni-directional Flushing (UDF) is used to improve operations and enhance the water system. Water main flushing is considered an effective method to remove unwanted tastes, odors, or discolorations of the water, and to improve chlorine residual. UDF, a specific type of water main flushing, uses less water than conventional flushing and provides greater cleaning of the pipes.

UDF isolates each pipeline to create flow in a single direction to quickly and efficiently clean the pipe. By concentrating the flow in one direction, UDF creates higher velocities that are better able to clean the pipe.  The major advantages of this method are improved cleaning of accumulated deposits on pipes, less required water than conventional flushing, and an impact reduction for customers


We started the Water Improvement Project in the spring of 2019 as an effort to clear our water mains of sediment and mineral build-up. This will not only extend the life of our water mains, but it will also improve water quality. 

This project includes Unidirectional Flushing, which involves systematically opening hydrants to “flush” mineral deposits from the pipes; and Ice Pigging, which is done by pumping an ice slurry into the main lines and forcing it along inside in order to scour the interior of the pipe and remove sediment.

We encourage you to subscribe to our website and CodeRed (our emergency notification platform). You will automatically receive updates about the project when your area is being affected.

Current Projects - Updated on 4/11/2021

2021 UDF - Where/When 

  • Contractor, HHydrant Flushing Photoydra-Tech, will be completing the unidirectional flushing in Zones 7 and 8 this spring
  • They started on, March 31, with the replacement of a water gate on Willow Street near Estabrook Road
  • They resumed the unidirectional flushing program in Zone 7 on April 1, and have been working on a daily basis, weather permitting. So far they have completed the flushing of Main Street from Route 140 to South Street, South Street from Main Street to Lamplighter Drive, Alden Avenue, Holman Street, Holman Heights Circle, Alice Avenue, Ruthen Circle, Park Street, Park View Lane, Park Street Place, Russell Avenue, Job Cushing Road, Gates Road Old Brook Road, .
  • We have several gates in Zone 8 that need to be replaced but the work will take significant coordination due to potential water service interruptions in large areas to allow for the isolation of the existing malfunctioning valves. This work will be completed during the week of April 19-23, weather permitting. These valves include Knowlton Avenue at Wesleyan Terrace and Hascall Street at Wesleyan Street. 

Town-Wide Status

This is a significant accomplishment for the Water and Sewer Division as this will mean 6 out of the 12 zones in the Town have been unidirectionally flushed since the fall of 2019 (Zones 1,2 5 and 6 have already been completed).

Flushing Program Zone Map
  1. Important Update from the Water and Sewer Division - Flushing to Resume Friday, 4/23 at 8:00AM

    Hydra Tech has finished flushing for today and will resume tomorrow, April 23rd, at 8:00 a.m. Today, they finished flushing Zone 8 and will continue with Zone 7 tomorrow. Read on...
  2. Important Notice from the Water & Sewer Division - Pressure Reducing Valve Testing on April 22

    On Thursday, April 22, 2021, beginning at 8:30 a.m., the Water and Sewer Division and the Town’s consultant, Tata and Howard will be performing flow testing of the pressure reducing valves. This testing is expected to be completed by 3:30 p.m. Read on...
  3. Important Update from the Water and Sewer Division - Water Valve Replacement is Complete

    Hydra Tech has finished replacing water valves at the intersections of Wesleyan Ter at Knowlton Ave, Wesleyan Ter and Wesleyan St, and Hascall St and Wesleyan St. We thank you for your patience and understanding as this work has been completed. Read on...
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More Information about Hydrant Flushing