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 5/10/2021

2021 UDF - Where/When 

  • Contractor, HHydrant Flushing Photoydra Tech, has completed the unidirectional flushing in Zones 7 and 8 this spring. They are currently working on unidirectionally flushing Zone 3.
  • They started the flushing season on March 31st with the replacement of a water gate on Willow Street near Estabrook Road
  • They resumed the unidirectional flushing program in Zone 8 on April 1st and completed it on April 22nd.
  • They replaced several water gates in Zone 7 on April 19th & 20th and completed flushing that zone on May 5th.

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 & Sewer Division - Sewer System Work will Continue Tomorrow, 7/29

    July 28, 2021, 5:00 p.m. update: Contractor National Water Main Cleaning Company is scheduled to continue the sewer system improvement project tomorrow, July 29th. The list of streets the contractor anticipates working on is included in the full message. Read on...
  2. Important Message from the Water and Sewer Division - Seasonal Water Use Restrictions

    Seasonal Water Use Restrictions are in effect beginning on May 1, 2021, and will end on September 30, 2021. Read on...
  3. Important Message from the Water & Sewer Division - Annual Drinking Water Quality Report

    The annual drinking water quality report for calendar year 2020 is now ready and can be viewed online. This document, also known as the Customer Confidence Report, contains valuable information about our drinking water. Read on...
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More Information about Hydrant Flushing