Controlling taste and odour events for the city of Philadelphia, USA: a case study Available to Purchase

The overall goal of this case study is to describe the history and present methods that the Philadelphia Water Department (PWD) uses to address its on-going earthy and musty drinking water T&O problems. The Philadelphia Water Department has developed a baseline for its water's aesthetic qualities since the early 1980’s. Philadelphia feels it has sufficient resources to control taste and odour problems. However, when directly asked, only 61–64% of the consumers are satisfied with the taste and odour of Philadelphia's drinking waters. A taste and odour early warning system is being developed for the two drinking water sources, the Delaware and Schuylkill rivers. Secondly, routine T&O panels and chemical analysis of geosmin and MIB are completed. Since the year 2000, 10 ng/L has become an early warning wake-up call for PWD. When higher levels are observed, testing is a priority, the source of the T&O is investigated and consumer complaints are monitored carefully. Present water treatment plants are conventional with chlorine disinfection, coagulation/sedimentation, rapid dual media filtration and final chloramination. The PWD uses powdered activated carbon, river water bypass and hydraulic changes in the distribution system to minimise odour events.