Unidirectional flushing: a powerful tool

Abstract

Unidirectional flushing can help ensure that water is delivered to the consumer's tap with minimum degradation in quality. Distribution system deficiencies continue to be responsible for more than 25 percent of waterborne disease outbreaks in the United States each year, a statistic that underscores the need for water suppliers to effectively control water quality within the distribution system. Flushing is one of the most powerful tools available to a water utility for maintaining this control. Unidirectional flushing (UDF) is a refinement designed to bring water through the system in a controlled fashion at velocities sufficient to provide a scouring action within the distribution piping. First developed in the early 1990s, UDF is being utilized by a growing number of utilities as a cost‐effective way of improving and preserving water quality in the distribution system. In this overview of 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.

The influence of flow rate on corrosion of mild steel in hot tap water

“…The hydroxyl ions are consumed by neutralization process (5), which eventually results in the deposition of CaCO 3 (6):…”

“…The latter increase the energy required to transmit water, support biofilm growth, and generate suspensions of iron particles that give drinking water a red, brown or yellow colour, or a dirty appearance [2][3][4]. Antoun et al [5] stated that in some cases, the deterioration of water quality could be a health threat to end-users. Semenza et al [6] pointed out that the deterioration of both water treatment facilities and the distribution system, posed a significant health threat to end-users living in republics of the former Soviet Union.…”

Securing Water and Wastewater Systems

“…The main cause of particle accumulation in the drinking water network in Latvia is due to high iron concentrations in the source (HIL 2011) (background pollution) and inefficient treatment. Within the EU 6FP Techneua project the application of the resuspension potential method (RPM) developed in Netherlands (Vreeburg et al 2004) for online turbidity monitoring in treatment plants and the unidirectional flushing (UDF) technique (Antoun et al 1999;Friedman et al 2002) for water quality control/improvement were carried out. These techniques were applied in several municipalities (population from [1,000-700,000; network length: 2-1,374 km; DN 100-DN 400).…”

Development of performance indicators for small Quebec drinking water utilities

“…Periodical flushing may be an efficient way to ensure overall distribution system healthiness, since it makes it possible to remove biofilm and corrosion tubercles, both favoring drinking water microbiological quality deterioration within distribution lines (Antoun et al, 1999;Duranceau et al, 1999). Therefore, the distribution system flushing variable was retained for the utility performance indicator development.…”