Application of portable fluorescence spectrophotometry for integrity testing of recycled water dual distribution systems.

Water utilities supplying recycled water to households via a "third-pipe" or "dual reticulation" system have a need for a rapid, portable method to detect cross-connections within potable water reticulation networks. This study evaluates portable fluorimetry as a technique for cross-connection detection in the field. For the first time, an investigation of a full-scale dual reticulation water-recycling network has been carried out to identify cross-connections using a portable fluorimeter. We determined that this can be carried out with a 3 mL water sample, and unlike methods that are currently in use for cross-connection detection, can be achieved quickly without disruption to water flow or availability within the network. It was also revealed that fluorescence trigger values could be established with high levels of confidence by sampling less than 2.5% of the network. Fluorescence analysis was also able to uncover a single, real cross-connection event. As such, this paper is a fundamental demonstration of fluorescence as a reliable, highly portable technique for cross-connection detection within dual reticulation water recycling networks and further establishes the abilities of fluorescence devices as valuable field instruments for water quality monitoring.