Tampa Bay Water (TBW) manages drinking water resources for the cities of New Port Richey, St. Petersburg, and Tampa, and Hillsborough, Pasco, and Pinellas counties, all in the state of Florida. Groundwater had been historically utilized for drinking water supply; however, adverse environmental impacts have mandated that alternative sources (desalinated seawater and treated surface water) be used now. Although all delivered water met contractual requirements that exceeded those specified in the SDWA, the quality was not constant, hence a project to determine the effects of blended waters on the regional distribution system water quality was conducted. The primary project objective was to determine the effects of blending finished waters produced from ground, surface, and saline sources on distribution system water quality. For this project, the effects were determined by the corresponding iron release, copper release, lead release, biological stability, residual maintenance, biological nitrification, and transition of iron, copper, and lead following changes in distribution system water quality due to blending.