Monitoring Adenosine Triphosphate Concentrations in a Chloraminated Drinking Water Distribution System for Risk and Asset Management

Abstract

Utilities rely on reliable and robust monitoring systems to inform decisions around asset operation and management in the drinking water distribution system (DWDS) to deliver high quality, biologically stable drinking water to consumers. However, traditional culture-based testing methods present challenges that make the timely detection of regrowth in the DWDS difficult. This study reports the results of an extensive adenosine triphosphate (ATP) monitoring campaign—a non-regulated parameter—in an urban, chloraminated drinking water system that analyzed over 5000 samples from two drinking water treatment plants (DWTPs), associated DWTP reservoirs, twelve outlying reservoirs and the DWDS between 2019–2022. ATP concentrations increased significantly between the two DWTP reservoirs and outlying reservoirs but decreased between the outlying reservoirs and DWDS samples. Relationships between ATP concentrations and other water quality variables varied depending on sampling location. Heterotrophic plate counts (HPC) were mainly non-detects (<1 CFU/mL) providing limited operational guidance compared to ATP. ATP concentrations exhibited temporal and spatial variation but did not exceed the proposed 10 pg/mL corrective action limit suggested by the manufacturer. ATP concentrations were also able to inform outlying reservoir management decisions. Monitoring ATP could serve as a useful indicator of biological stability in the DWDS for the utility of the future.