Water Main Flushing Program


October 16-20 & 23-27


During the spring and fall seasons when residents are busy working on their lawns, CPW’s Water & Sewer Division is busy flushing our 130+ miles of water main. Flushing is routinely conducted during the spring and fall when the demand for water tends to be at its lowest and cold weather and potential freezing is not an issue.

Water mains are flushed for several reasons. Flushing allows hydrants to be used periodically and inspected for maintenance or replacement needs. It also provides an opportunity for routine exercising of water main valves and for testing to be to done to determine if water flow and pressure are sufficient.

Most importantly, flushing enhances water quality. It allows sediment built up in the water mains, especially at dead ends and in low-flow areas, to work its way out of the system. The high volume of water flowing causes a scouring action that draws the sediment out. Left alone, this sediment may cause discoloration when water flow changes, ultimately making its way into customer's homes and out of their taps.

Iron and manganese, which are naturally present in Concord's groundwater supplies, are the source of the sediment and color. It is recommended not to ingest (drink, cook, or prepare baby formula with) discolored water, but it is safe for activities such as bathing and dish washing.

 Every neighborhood gets flushed roughly every other year. Additional flushing is conducted if sediment historically has built up in certain neighborhoods, or if a large number of customers in a certain area have had water quality issues. A well-designed flushing program does not require water to flow from every hydrant. Our goal is to flush water mains, not hydrants.

Public notification of flushing is key to minimizing disturbances in customers’ homes. CPW publicizes the flushing schedule and general areas expected to be impacted the week before flushing starts. Look for this information in the Concord Bridge, on social media, via News and Notice News Flash emails, and on this webpage.

It is important to remember that flushing can cause discoloration in areas of Town not directly being flushed, and that the street listings published only indicate the general areas being worked in.

The benefits of unidirectional flushing activities are important to ensure that high quality water is maintained for essential uses like drinking and for adequate fire protection.


Updated October 6, 2023