Short-Term Temporal Dynamics of Disinfection By-Products in Drinking Water: Application of Innovative Polygon Trend Analysis Across Multiple Source Waters

Understanding short-term variations in disinfection by-products (DBPs) is essential for effective drinking-water management. This study applied Innovative Polygon Trend Analysis (IPTA) to evaluate temporal trends in DBP concentrations in treated water from 2011 to 2022 across four source-water types: river water (RW), riverbed water (RBW), underground water, and lake water. IPTA provides a visual framework for identifying month-specific and asymmetrical trends in environmental time-series data. A dataset from 82 treatment plants was analyzed. Trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs) were evaluated, with detailed correlation analysis performed for THMs due to complete data availability. Results indicate that THM concentrations decreased during January–April but increased during warmer months, with peak values observed in the 20–30°C range based on monthly average temperature data. THM concentrations were consistently lower in advanced treatment plants, with average reductions of ∼10–25% compared with conventional systems. HAAs exhibited seasonal variability, increasing during cooler periods and decreasing during warmer months in RW and RBW. IPTA effectively identified month-specific trend reversals and asymmetries across water sources. These findings highlight the importance of seasonal optimization of treatment processes, including precursor removal and chlorination control, and demonstrate the applicability of IPTA for operational monitoring and DBP management.