Assessing critical water quality indicators in raw and drinking waters of the main treatment plants in the city of Cuenca, Ecuador

Ecuador is a tropical country with wet and dry periods. The seasonality of water resources leads to water availability and quality variability. This study investigated the variability of physical-chemical characteristics (pH, colour, turbidity, and conductivity), aluminum content, residual free chlorine, and caffeine levels in the inlets and outlets, and in the distribution networks of the three main drinking water treatment plants in the city of Cuenca: El Cebollar (Tomebamba River), Sustag (Yanuncay River), and Tixan (Machangara River). Samples were collected from May 2023 to December 2024. The average values for each parameter fell below regulatory limits. No caffeine was detected. There were isolated instances of values exceeding the regulatory standard for aluminum in inlet and distribution samples. A deficiency of free chlorine was also observed at some points in the distribution system, which might be due to the distance from the treatment plant and the state of the pipes. These findings indicate the quality of Cuenca's drinking water. However, more water quality controls should be implemented throughout the distribution network.