Unidirectional Flushing Program

What is Unidirectional Flushing?

Unidirectional flushing (UDF) is common among water utilities who wish to improve water quality and properly maintain their water distribution system.  A UDF program involves opening and closing valves in a specific sequence to create water movement in one direction.  The water is then flushed out through a fire hydrant at the end of the sequence.  UDF creates higher velocities of water flow through the system, which scours the pipes to dislodge and remove mineral deposits and sediments that accumulate in the water mains over time.  While traditional line flushing uses a lot of water, the UDF method uses up to 40% less water than these traditional methods.  In addition to ensuring that the assorted valves and hydrants are functioning properly, UDF also helps reduce bacteriological growth, improves disinfection, and improves the aesthetic quality of our water supply.

How May Water Customers be Affected?

In most cases, customers will not notice any changes to their water delivery during the UDF process.  In some cases however, homes may experience a temporary slight drop in water pressure, or discolored water.  Customers should not experience an interruption in water service during the flushing process.

If You Notice Discolored Water:

It is normal for customers to experience some degree of discolored water for a short period during and immediately after the flushing process.  The material that is causing the discoloration is common within water distribution systems and is not harmful to your health.  Prior to using the water for typical indoor uses such as cooking or clothes washing, customers should turn on their cold water taps until their water runs clear.  This process should only take a few minutes to complete. 

If the water does not clear up by using this process, please notify Tumwater Public Works at (360) 754-4150.

Frequently Asked Questions Regarding Tumwater’s UDF Program

Water Zone Map

Updated: February 13, 2009