The City of Houston completed the construction of a permanent pilot research facility in the fall of 1997 to investigate new and emerging technologies, as well as optimizing current treatment processes. As part of an ongoing study, the City of Houston's research group has, and will continue, to evaluate the effectiveness of ozone disinfection as a means of reducing the formation of DBPs in the City of Houston's drinking water. Although the City of Houston has two raw water sources (Trinity River and San Jacinto River), this phase of the ozone study focused primarily on Trinity River water. Preliminary bench and pilot studies results using Trinity River water show substantial reduction in TTHM and THAA concentrations, and that bromate formation was not a problem when ozone was used as a pre-, intermediate, or post disinfectant. The reductions in DBP concentrations were well below the proposed MCLs for THAAs and TTHMs. When ozonation and enhanced coagulation were implemented together, a greater reduction in total organic carbon concentration was achieved than was achieved using enhanced coagulation alone. The ozonation process improved the overall finished water quality, true color, Threshold Odor Number, and the coagulation efficiency was improved (reduced coagulant dosages) when ozonation was implemented prior to the coagulant addition. Includes 5 references, tables, appendix.