The effectiveness of ultraviolet radiation (UV) from low and medium pressure mercury lamps against relatively UV-resistant adenoviruses in drinking water is uncertain. Therefore, their effectiveness as collimated beams against adenoviruses 5 and 41 was investigated. In buffered saline (BS), log[10]Ad5 reductions at UVdoses of 40, 80, and 120 mJ/cm^2 were 1.8, 2.9, and 3.5, respectively, with LP lamps and 2.9, 3.8, and 4.7, respectively, with MP lamps. Ad41 log[10] reductions at UV doses of 50, 100, and 150 mJ/cm^2 were 0.35, 1.1, and 2.4, respectively with LP and 0.8, 1.6, and 3.4, respectively with MP. Log[10] Ad5 reductions by LP UV doses of 40, 80 and 120 mJ/cm^2 were 1.3, 2.2, and 3.0, respectively in colored natural water (DOC~20mg/L) and 1.6, 3.6, and 4.3 in this same water with 5NTU clay turbidity. These data inform decision-making on UV disinfection guidance for drinking water.Master of Science in Public Healt
