This report summarizes the current state of knowledge on the persistence of biological agents on drinking water infrastructure (such as pipes) along with information on decontamination should persistence occur. Decontamination options for drinking water infrastructure have been explored for some biological agents, but data gaps remain. Data on bacterial spore persistence on common water infrastructure materials such as iron and cement-mortar lined iron show that spores can be persistent for weeks after contamination. Decontamination data show that common disinfectants such as free chlorine have limited effectiveness. Decontamination results with germinant and alternate disinfectants such as chlorine dioxide are more promising. Persistence and decontamination data were collected on vegetative bacteria, such as coliforms, Legionella and Salmonella. Vegetative bacteria are less persistent than spores and more susceptible to disinfection, but the surfaces and water quality conditions in many studies were only marginally related to drinking water systems. However, results of real-world case studies on accidental contamination of water systems with E. coli and Salmonella contamination show that flushing and chlorination can help return a water system to service. Some viral persistence data were found, but decontamination data were lacking. Future research suggestions focus on expanding the available biological persistence data to other common infrastructure materials. Further exploration of non-traditional drinking water disinfectants is recommended for future studies.

Multi-species water quality models can be used to predict the fate and transport of contaminants such as arsenic in water distribution networks. In recent work, water quality models have been used to simulate hypothetical contamination events, estimate potential human health effects, and characterize the ability of sensors to detect contamination. Little work has been done to calibrate water quality models and validate them against experimental data generated in Distribution System Simulators (DSSs). In this paper, results are reported from bench scale and pilot scale experiments performed with a DSS at U. S. EPA's Test and Evaluation Facility in Cincinnati, Ohio. The parameters for a reversible adsorption model were estimated from bench scale data generated over two days. The model was used with the EPANET-MSX software package to simulate the pilot scale experiment in the DSS. Model results match the pilot scale data very well for the first two days after the arsenate injection, however pilot scale data after this time deviates from model predictions. This deviation may be due to limitations in the time scale or sample size of the bench scale experiment. Additional modeling, simulation, and experimental work is planned to develop a fate and transport model that can be used in practical settings to design decontamination strategies following intentional arsenic contamination of water distribution systems.

No abstract

This article discusses the 2009 U.S. Environmental Protection Agency (USEPA) report “Distribution System Water Quality Monitoring: Sensor Technology Evaluation Methodology and Results”, which summarizes the testing of on‐line (i.e., real‐time) water quality sensors. The report includes operation and maintenance data that drinking water utilities need in order to make informed decisions about sensor selection. Best practices and lessons from practical, hands‐on experience that comes from working with water quality sensors every day are also presented. Finally, the report discusses sensor testing protocols that are being used at USEPA's test and evaluation facility that benefit equipment vendors and manufacturers interested in designing sensors for community water systems.

No abstract