Improving early detection by water utilities of sensory defects in water

Sensory evaluation of water quality can achieve sensitivity exceeding that of any chemical analysis practicable in a treatment works, so tasting of water is one of the routine duties of plant workers. This can give warning of an unexpected change in water quality long before analysis at a central laboratory can be carried out. However, the procedures currently specified for sensory evaluation are inefficient and take no account of modern psychophysics. Adding occasional, artificial samples on which feedback was given halved the frequency both of false alarms and of missed odours in a laboratory simulation of conditions in a treatment works.