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Water Main Flushing Program

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Water Related Issues or Requests

Customer Service Center

Water System Flushing 

Water system flushing is a periodic maintenance activity to clean and flush the City water main lines. Over time, particles and minerals can build up in the water mains. Flushing is the process of cleaning or "scouring" the interior of water distribution mains (pipes) by sending a rapid flow of water through the mains.  It is an important part of water distribution maintenance for several reasons but mainly aids in the improvement of drinking water quality.

Flushing involves isolating a section of the water distribution system and opening fire hydrants to release water at a high flow rate.  The increased flow helps remove material that has built up over time in the mains, such as minerals and accumulated sediment. Flushing requires staff to open and close valves and monitor residual pressures (water pressure remaining in the system while a fire hydrant is flowing).

Benefits of Flushing

Flushing enhances water quality and helps maintain the water system. Flushing allows sediment built up in the water mains, especially dead ends and low-flow areas, to work its way out of the system. The high volume of water 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.

  • Bacteria Control - Biofilm growth can occur when an area becomes stagnant
  • Taste & Odor Control - Flushing removes many of the deposits, sediment, and other materials that can affect taste and odor.
  • Corrosion Control - The rapid flow of water scour the inside of lines and reduces corrosion.
  • Hydrant Maintenance - Allows hydrants to be periodically used and identified for maintenance or replacement.

Customer Impacts of Flushing

Flushing may cause periods of discolored water and reduced water pressure in localized areas where flushing is being conducted. The discoloration is due to particles and minerals that have settled in the main lines being mobilized by the high velocity water before they are discharged through the fire hydrants. The water will remain safe to use and generally clears within a few hours after flushing has been completed.

The water used for flushing is not considered waste because it performs an essential water quality function and is a planned investment for maintaining the water system. The amount of water used is dependent on the amount of particles and minerals to be removed and the size and length of pipe to be cleaned. It is neither practical nor cost effective to capture the high velocity flows of discharged water. Staff use dechlorination tablets to remove chlorine in the water before the water goes into the storm drain system.