Determination of the Occurrence of Trihalomethanes in the Drinking Water Supply of the City of Cuenca, Ecuador

Water chlorination, fundamental for its microbiological safety, generates by-products, such as trihalomethanes (THMs), potentially associated with carcinogenic and reproductive risks. This study determined the levels of chloroform (CHCl3) in drinking water in Cuenca, Ecuador, a topic that has been little explored in the region. During five months, water samples were collected from three water treatment systems (Cebollar, Tixan, and Sustag), and in situ measurements of physicochemical parameters such as free chlorine, pH, temperature, electrical conductivity, and turbidity were performed in the storage and distribution area. The determination of CHCl3 was performed following the Hach protocol. For data analysis, the Kruskal–Wallis test was employed, followed by Dunn’s post hoc method and Spearman’s correlation coefficient. The results revealed a progressive decrease in free residual chlorine throughout the distribution systems. CHCl3 concentrations ranged from 11.75 µg/L to 21.88 µg/L, remaining below the Ecuadorian regulatory limit of 300 µg/L. There was no consistent correlation between CHCl3 and physicochemical parameters. These findings align with previous research, suggesting that the variability in CHCl3 formation is associated with different water treatment conditions and environmental variables. This study highlights the importance of monitoring disinfection processes to minimize THMs and other DBPs, ensure public health, and contribute to sustainable drinking water management in Ecuador.