Increasing Application of Water Quality Models

Hydraulic and water quality models of water distribution systems have served as the basis for several areas of research, development and application in the water industry. Faced with meeting more stringent federal and state rules utilities are finding water quality tools very useful for performing tasks such as computing water age, tracking disinfection residuals, predicting the vulnerability of water systems, locating optimal monitoring sites, developing a disinfection plan, and performing post-incident forensic analysis. A well-calibrated hydraulic model provides the basis for answering critical questions on facility operations and sizing. However, there is a growing need for assistance in understanding and interpreting results from water quality samples the utilities are monitoring. Operational data and hydraulic models can be used to develop a better understanding of water quality dynamics and initial recommendations for managing and improving water quality. Typical water quality complaints that utilities have to deal with on day-to-day basis include loss in disinfectant residual, complaints of taste and odor, colored water problems, and high concentrations of disinfection by-products. When utilities examine sampling data, particularly for complaint sites, they are often left with more questions than answers. From which source did the water sample come from? Could the source of the problem be a particular facility? Why is there low residual at a particular location? What caused the increase in disinfection by-products at a particular location? Water quality modeling results provides clues that can help to divulge such water quality dynamics of the system. GIS enabled water quality models facilitate mapping of model outputs allowing easy interpretation and quick comparison of modeling results. The graphical results are helpful in determining where disinfection booster location is needed, how DBP formation can be controlled, how different sources are blending in the system, and how water quality is changing throughout the network. Current water quality models have limited capabilities but new algorithms are being tested, mostly in research field, which can bolster the applicability of water quality models. Although fully calibrated water quality models require a high level of sophistication, less detailed tools are available to provide immediate insights into water quality dynamics of the system. This study summarizes how utilities throughout the country, small to big, are utilizing the water quality tools with different levels of sophistication to understand, manage and improve their water quality.