AWWA JAW23801

Swampy odors occurred in some areas of Perth, Western Australia, supplied with treated groundwater. The odors, caused by dimethyl trisulfide, developed in the water supply mains when chlorine demand was not satisfied. When swampy odors occurred, flushing of water mains reduced the number of complaints. The addition of 2 mg/L or more of chlorine also eliminated the swampy odor. To control the formation of swampy odors in mains, an extra 2-5 mg chlorine/L was added at the outlet of the groundwater treatment plant, thereby increasing the concentration of free chlorine at most points in the water supply system. Since this strategy was instituted, complaints of swampy odors have almost ceased. Includes 55 references, tables, figures.