Unidirectional Flushing Program

As part of continued efforts to properly maintain the City’s water distribution lines and ensure that our drinking water remains as high of quality as possible, the Utilities Distribution Division has a Unidirectional Flushing (UDF) program.

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What is UDF?

During UDF, water is forced through a water pipe at a velocity high enough to remove material build-up from within the pipe. The water used during the UDF process is discharged through a fire hydrant. Material removed in this process is harmless and requires no special treatment. 

The process includes a discovery phase in which staff identifies all valves and hydrants within that section of the system. Repairs and/or replacements are made as needed to fire hydrants, valves and lines to ensure the integrity of the system. Asset data is collected and verified and entered into the City's asset management program. 


Working in small sections of the City's water system, crews will systematically flush over a 6 to 7 month period. Prior to flushing an area of town, crews will notify affected residents through door inserts.

Results of the 2017 UDF Program

  • 14,203 feet of water main flushed
  • 391,000 gallons of water flushed
  • 284 valves exercised
  • 33 valve boxes replaced or raised
  • 190 valves found
  • 4 hydrants repaired