AWWA JAW72323

AWWA JAW72323 Journal AWWA - Determining Vulnerability and Occurrence of Residential Backflow

Journal Article by American Water Works Association, 08/01/2010

Schneider, Orren D.; Hughes, David M.; Bukhari, Zia; LeChevallier, Mark; Schwartz, Paul; Sylvester, Patrick; Lee, J.J.

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Full Description

Backflow from customer service connectionsis of concern to water utilities, but fewdata about the frequency of such occurrencesexist and little is known about how to monitorfor backflow into the distribution system.For the first time, occurrence statistics forresidential backflow have been quantified.As it turns out, backflow is a much morewidespread problem than currently believed.Backflow has now been shown to occur in1.6% of all meter reads and in 5% of homeswith backflow-sensing meters.Using pilot tests to examine the effectivenessof water quality sensors to detect a rangeof contaminants, the authors found that eventhough the monitors were sensitive to smallchanges in quality, they cannot be used toassess the public health effects of such events.This is because wide variations in backgrounddistribution system quality overwhelmed theability of current data processing technologyto differentiate between water quality fluctuationscaused by backflow from those attributableto normal variability.Backflow-sensing meters, combined withan effective pressure management programto minimize or eliminate pressure transients(a primary cause of backsiphonage cross-connections)and integrated into a fixednetwork automated meter reading/advancedmetering infrastructure system, can provideutilities with near real-time information onbackflow events. The analyses conducted inthis study show that the use of backflow-sensingmeters is the best available technologyfor determining the occurrence of residentialbackflow. Given the benefits shownby these meters, their slightly higher cost($15-$20/meter) over regular meters ismoney well spent.

Includes 7 references, tables, figures.

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