AWWA ACE93148

Before the Total Coliform Rule, the East Bay Municipal Utility District (EBMUD) used both free chlorine and chloramines as a residual in the distribution system. However, more detailed sampling under the Total Coliform Rule revealed higher levels of total coliform at the outermost extremes of the distribution system in the higher pressure zones. The past disinfection practice was to maintain a total chlorine residual of 0.35 to 0.4 mg/L entering the distribution system, with chlorine residual at trace levels and nonexistent at its extremities. The Total Coliform Rule changed all that. A detailed total Coliform Rule Action Plan highlighted the need for new operating procedures, staffing,a nd facilities needed. The chlorine residual increase controlled total coliforms. However, more customers complained about the water's taste. Also, trihalomethane levels have increased.