Unidirectional flushing: a powerful tool

Distribution system deficiencies continue to be responsible for more thane 25 percent of waterborne disease outbreaks in the United States each year, a statistic that underscores the need for water suppliers to effectively co ntrol water quality within the distribution system. Flushing is one of the most powerful tools available to a water utility for maintaining this contr ol. Unidirectional flushing (UDF) is a refinement designed to bring water t hrough the system in a controlled fashion at velocities sufficient to provi de a scouring action within the distribution piping. First developed in the early 1990s, UDF is being utilized by growing number of utilities as a cos t-effective way of improving and preserving water quality in the distributi on system. In this overview csf UDF, the authors summarize the technique's key components and potential benefits and explore how UDF fits into overall efforts to control distribution system water quality.