LAUSR

Abstract Chlorination is the oldest and most common method to control water quality and biofouling worldwide. Therefore, ensuring the accuracy of the measurements of residual chlorine concentration in treated water is of significant importance. Various residual chlorine measurement methods are used for industrial and municipal (conventional) or academic research (unconventional) purposes. Previous studies have reported that the conventional methods suffer from diverse interferences that lead to erroneous measurements. However, no recent study has summarized and synthesized the existing interferences related to the measurement methods. In this review, the conventional electrochemical and colorimetric-photometric methods are discussed, along with the unconventional methods, with regard to their principles, advantages, limitations, and recent case studies. Further, conventional method interferences are defined and discussed. In particular, possible solutions for interferences in the widespread colorimetric-photometric method are extensively evaluated, and constructive suggestions are offered toward reducing or avoiding the effects of these interferences.