Unidirectional Flushing

The City of Concord Water Resources Department has started a new program called Unidirectional Flushing.  City crews will be flushing water through fire hydrants to clear sediment from the water pipes.  This work will be performed Monday through Friday from 8am-4pm.

 

 

This program will start in the Midland area, using the zones shown below, beginning in Zone 1.  

 

Unidirectional flushing is used to improve and maintain our high-quality drinking water. Sediments and mineral deposits in the pipes can discolor drinking water. The high-speed water flows used in unidirectional flushing is an efficient and cost-effective way to remove sediments and deposits from the pipes and prevent potential water quality issues.​​

Concord uses three techniques to clean and maintain the drinking water system: spot flushing, auto flushing, and unidirectional flushing. 

  • Auto-flushing is similar to spot flushing and is used to maintain water quality by reducing the water age in the distribution system. This type of flushing uses an automatic flushing device, called an automatic blow-off, which is connected to the water main and programmed to flush water at certain time intervals and flow rates. Using an automatic blow-off reduces the amount of staff time needed to maintain consistently better water quality at a certain location in the distribution system while using water in a more efficient manner.
  • Conventional Flushing is used to address discolored water issues. This includes when drinking water is discolored due to a disturbance in the system such as construction or other hydrant activity. Crews open fire hydrants to flush this water out of the system and bring fresh water into the pipes. 
  • Unidirectional Flushing is not used in response to a specific water quality issue but instead is used as routine maintenance to prevent problems from arising. The goal of unidirectional flushing is to clean the insides of the water delivery pipes. Cleaning the pipes removes sediment that builds up in the pipes. This reduces the potential for water quality problems. Unidirectional flushing works by forcing water in the pipes to flow at much higher speeds than normal. Flushing crews first open and close valves to isolate sections of pipe, and then the water and any mineral sediments in the pipes are flushed out through an open fire hydrant.

 

Customers in the immediate vicinity may notice temporary, discolored water (caused by turbulence of the flushing process) and lower then normal water pressure.  The discoloration does not pose any type of risk.  While the water is safe, it is recommended that customers run the faucets for 5-10 minutes until the water appears clear.

Please call 704-920-5342.