The report summarizes the surveillance of waterborne disease outbreaks associated with drinking water in the United States from 2015 to 2020, as reported through the National Outbreak Reporting System (NORS). During this period, 214 outbreaks were reported by public health officials from 28 states, involving both public and private drinking water systems. The outbreaks resulted in at least 2,140 cases of illness, 563 hospitalizations, and 88 deaths. The majority of outbreaks (80%) were linked to public water systems, while individual or private water systems were implicated in 43% of cases. The etiologies of the outbreaks included 187 biofilm-associated cases (87%), 24 enteric illness-associated cases (11%), and three other cases (1%). Biofilm-associated outbreaks were predominantly caused by Legionella, with 184 cases (98%), followed by nontuberculous mycobacteria (NTM) and Pseudomonas. Legionella-associated outbreaks increased over the study period and were the leading cause of hospitalizations and deaths. Enteric illness outbreaks, primarily linked to wells, represented approximately half of the cases during the reporting period. The report highlights the complexity of drinking water-related disease prevention and the need for water source-to-tap prevention strategies. It emphasizes the importance of effective regulations, water management programs, and public health prevention programs to reduce the risk of biofilm pathogen growth and spread in public drinking water systems, building water systems, and private homes. The findings underscore the critical role of public health surveillance and outbreak response in monitoring and controlling waterborne diseases.The report summarizes the surveillance of waterborne disease outbreaks associated with drinking water in the United States from 2015 to 2020, as reported through the National Outbreak Reporting System (NORS). During this period, 214 outbreaks were reported by public health officials from 28 states, involving both public and private drinking water systems. The outbreaks resulted in at least 2,140 cases of illness, 563 hospitalizations, and 88 deaths. The majority of outbreaks (80%) were linked to public water systems, while individual or private water systems were implicated in 43% of cases. The etiologies of the outbreaks included 187 biofilm-associated cases (87%), 24 enteric illness-associated cases (11%), and three other cases (1%). Biofilm-associated outbreaks were predominantly caused by Legionella, with 184 cases (98%), followed by nontuberculous mycobacteria (NTM) and Pseudomonas. Legionella-associated outbreaks increased over the study period and were the leading cause of hospitalizations and deaths. Enteric illness outbreaks, primarily linked to wells, represented approximately half of the cases during the reporting period. The report highlights the complexity of drinking water-related disease prevention and the need for water source-to-tap prevention strategies. It emphasizes the importance of effective regulations, water management programs, and public health prevention programs to reduce the risk of biofilm pathogen growth and spread in public drinking water systems, building water systems, and private homes. The findings underscore the critical role of public health surveillance and outbreak response in monitoring and controlling waterborne diseases.