The City of Alcoa, Tennessee has a long-standing commitment to providing safe and reliable drinking water, with more than 61 years of continuous water service to its community. In the early 2000s, the City made an innovative investment by implementing full-scale membrane filtration at its Water Treatment Plant at a time when the technology was still emerging in the southeastern United States. Unlike conventional treatment processes, membrane filtration provides a physical barrier to contaminants, enabling enhanced removal of turbidity, pathogens, and particulate matter while offering increased process control and resilience to source water variability. When commissioned, the facility was among the first full-scale membrane filtration plants for drinking water in the State of Tennessee. In 2026, exactly twenty years since the plant first came on, the Alcoa Water Treatment Plant remains one of the larger membrane filtration facilities in Tennessee, with a rated capacity of 16 MGD and the ability to expand to 24 MGD, and it continues to provide an exceptional quality of drinking water. The primary focus of this presentation is a review of twenty years of membrane plant operation. Drawing on both engineering and operations perspectives, the presenters will evaluate long-term membrane performance, operational reliability, and how operations and maintenance practices have evolved over time. Insights from the plant supervisor, who has worked at the facility for over 18 years, will be paired with a consulting engineer’s perspective to discuss membrane longevity, maintenance demands, system resiliency, and adaptability to changing regulations and source water conditions. The discussion will highlight both shortcomings encountered and areas where the membrane system has exceeded original expectations. To provide context for this long-term operational review, the presentation will also briefly summarize the City of Alcoa’s unique history and water system, the regulatory and water quality drivers that led to the original decision to pursue membrane filtration, and the design and implementation of the original membrane treatment facility by Smith Seckman Reid, Inc. (SSR). Finally, the presentation will look ahead to the future of the Alcoa Water Treatment Plant, including capacity expansion potential, aging infrastructure considerations, evolving treatment technologies, and long-term planning goals. This retrospective offers a rare, two-decade case study of full-scale membrane filtration and provides practical insights for utilities, operators, and engineers considering advanced treatment technologies and long-term lifecycle performance.