AWWA DSS71332

Tampa Bay Water (TBW) is a regional water supplier in Florida that serves nearly two million consumers at a 250 MGD average daily demand. TBW has historically used groundwater for its drinking water source; however, alternative sources like surface and desalinated water are also utilized to reduce sole dependency on groundwater and limit withdrawals to protect the aquifers. The impact of new source waters and their blends on water quality changes was previously evaluated under a tailored collaboration project (TCP) conducted by the University of Central Florida (UCF) and funded by TBW and WRF (then AwwaRF). Prior research using blended waters had identified conflicting objectives for control of iron and copper. Operation with a blend that is enriched in groundwater, with an associated elevated alkalinity, would be desirable to mitigate red water problems associated with release of iron from unlined cast iron and galvanized iron pipe materials. Unfortunately, the elevated alkalinity also creates compliance problems for copper. This study evaluated the corrosion control strategies of pH elevation and inhibitor addition to determine whether the feasible operating domain for alkalinity and thus, blend composition, could be expanded without violation of secondary standards for iron (or apparent color) or the copper action level. Prior to this study, the system effects of corrosion inhibitors on the regional distribution of varying water quality were unknown. Includes 13 references, tables, figures.