Project #4653

Use of Flushing as a Corrective Action Under the Revised Total Coliform Rule

Principal Investigator
Research Manager
Hyunyoung Jang, PhD
Confluence Engineering Group, LLC
Microbes & Pathogens
Distribution System Management
Water Quality


Utilities and regulators need guidance to demonstrate that flushing is a corrective action under the Revised Total Coliform Rule (RTCR) by preventing coliform regrowth and biofilm formation, reducing disinfectant demand, and avoiding unintended consequences. This project compared flushing techniques that are routinely applied (or misapplied) by utilities throughout North America and beyond. The deliverables include flushing protocols, data collection Standard Operating Procedures and decision trees, and information on cost vs. measured benefit for each flushing technique. This research allows utility managers to better allocate O&M resources to optimize flushing practices to both prevent and respond to coliform events. Tailored collaboration partners: Portland Water Bureau and Seattle Public Utilities. Published in 2018.