The Mark B. Whitaker (MBW) Water Treatment Plant is Knoxville Utilities Board’s sole water treatment facility, supplying potable water to customers across Knoxville and surrounding communities. All treated water produced at MBW is delivered to the distribution system through the plant’s high-service transmission mains, making this portion of the facility the only conveyance between treatment operations and the water system. In late September 2024, suspicions arose of a water leak in the high service area of the MBW property. While system operations remained stable during leak investigation efforts, the situation escalated on October 6, 2024, when a catastrophic failure occurred on one of the plant’s two 42-inch high-service transmission mains. Immediate action was required to stabilize the system and protect continuous service. To maintain operations and allow repairs to proceed safely, KUB partnered with Garney Construction, to rapidly design, source, and construct a temporary 30-inch HDPE bypass of the failed 42-inch high service main. The bypass was assembled, disinfected, pressure-tested, and placed into service in less than ten days, allowing for the excavation and repair of the failed main while continuing to consistently supply Knoxville with water. During repair activities, additional failures were identified, requiring expanded emergency repairs under continuous operations. Despite the scale and complexity of the event, system stability was maintained and widespread customer impacts were avoided. This presentation will provide an overview of the investigation, emergency response, bypass implementation, and system recovery, with lessons applicable to utilities managing critical transmission infrastructure.