Questionnaire Survey on Installation of Online Water Quality Monitors and Data Utilization for Water Supply Systems in Japan

In recent years, Japanese water utilities are facing pressing problems like staff shortage and climate-induced water quality deterioration. Utilization of online water quality monitoring data have received increasing attention to address these problems. A questionnaire survey was carried out for 32 water utilities to comprehend current situation of online water quality monitors (OWQMs), including installation of OWQMs and critical obstacles, water quality items monitored, utilization of water quality dataset, and future challenges. Turbidity, pH, and chlorine were mostly monitored using OWQMs from source to tap, for determining operating conditions of water purification process. Turbidity, pH, toxic substance, musty-odor substance, and residual chlorine were regarded as highly significant for both operational management and risk management. Initial/operational costs, measurement accuracy, and maintenance work volume were typical obstacles of OWQM installation. Nineteen out of the 32 water utilities have utilized water quality dataset obtained by OWQMs for predicting residual chlo-rine/bromate concentration, and for determining injection ratio of chemical coagulant and powdered activate carbon. Further OWQM installation and data utilization would be the key to strengthen the basis of water supply systems in Japan.