Temperature dynamics and water quality in distribution systems

Quality assurance strategies for water distribution systems often include the application of chemical disinfectants to limit the growth and transmission of pathogens. Characteristics of water quality in individual systems, and the type of disinfectant employed, create significant complexity in understanding and quantifying the impact of disinfectants in different networks. An additional challenge is that disinfection by-products (DBPs), created through the breakdown of disinfectants, can be detrimental to human health. Therefore, it is necessary to maintain the correct level of disinfectant to control microbial pathogens while also limiting formation of DBPs to acceptable levels. Limiting formation of DBPs is an ongoing challenge for operators. This work examines the impact of ground surface temperature and changes in network operations on disinfectant breakdown. As drinking water utilities encourage customers to conserve water, water residence times within networks increase. Also, as surface temperatures increase, heat transfer into the drinking water in subsurface pipes can also increase. Here, we review the literature on ways in which temperature affects disinfection rates and the production of DBPs and select one pathway for more detailed assessment. Numerical modeling is used to examine the changes in DBP production as a function of residence time, ground surface temperature, and heat transfer through the soil to the pipe.