Tuesday, September 10, 2024
8:45 AM - 9:15 AM
Location Name
Flowing Forward: Importance of Backflow Prevention and Cross-Connection Control for Water Systems
Distribution Water Quality

The protection of potable water systems from contamination due to backflow incidents is a pressing concern for public water systems (PWSs) across the United States. This paper focuses on the experiences and strategies of three utilities – one in Ohio and two in North Carolina – in implementing backflow prevention and cross-connection control programs. The study also gleans insights from other utilities to illustrate the nationwide efforts in safeguarding water quality. Backflow, the unintended reversal of water flow in a distribution system, can introduce harmful contaminants into potable water supplies. This risk arises from cross-connections, which are potential or actual connections between a potable water system and a nonpotable source. The incidence and impact of backflow events vary across regions due to differences in state drinking water programs, building codes, and health department regulations. For instance, a 2010 study by the Water Research Foundation highlighted that 5% of homes experienced a significant backflow incident each year. Another report indicated that over 10,000 backflow incidents, including backsiphonage events, were reported in the U.S. between 2015 and 2020, affecting numerous households and businesses. However, the broader implications of these events on water system disinfectant residuals are not fully understood. The implementation of cross-connection and backflow prevention programs is not uniform and presents unique challenges. The utilities in Ohio and North Carolina exemplify the diversity of approaches taken to tackle these issues. Key indicators of backflow incidents include customer complaints, reductions in water pressure, short-term drops in disinfectant residuals, and water meters indicating reverse flow. The paper presents cases from different regions of the U.S. to underscore the severity of backflow incidents. In the western U.S., a small PWS encountered E. coli contamination due to a customer-created cross-connection. In the southeastern U.S., a large PWS faced a significant incident where fire-fighting foam was forced back into the system, impacting thousands of homes. These examples highlight the aftermath of backflow incidents and the reactive measures often taken, such as installing backflow prevention assemblies post-incident. Advocating for a proactive approach, the paper stresses the importance of having a formal program with clear processes and responsibilities supported by regular surveys as a means to identify and mitigate potential cross-connections. These surveys, required at least once every three to five years, are crucial for early detection and prevention of backflow events. In conclusion, the paper discusses the need for the integration of cross-connection control and backflow prevention into a comprehensive strategy for maintaining water quality in distribution systems. The experiences of the utilities in Ohio and North Carolina offer valuable lessons and benchmarks for other PWSs aiming to enhance their backflow prevention efforts. By sharing these insights, the paper contributes to the collective knowledge and best practices in the field, emphasizing the need for continual improvement and vigilance in protecting public health and water resources.