A brief discussion of the physics involved in the destruction of micro organisms by exposure to 2537A of UV energy: UV dose required for destruction of various micro organisms in a dynamic UV reactor (Bio Assay). History of UV design for shellfish depuration: Kelly Purdy Overhead design, Closed channel reactore, Open channel horizontal reactors, Open channel vertical reactors. Factors which effect UV performance: Chemical make up of water-coefficient of absorption, Physical make up of water-turbidity and Color impact, Overall UV transmission limits for effective disinfection. Discussion of the U.S. Public Health Service: effects of color, turbidity, and bacterial densities on UV performance. Impact of temperature on UV lamp performance. Impact of coating on Quartz Jackets. Methods to recognize coatings and loss of UV transmittance in various design configurations. Depuration UV system: UV lamp to flow ratios, Temperature control, Intensity monitoring, Lamp life monitoring, Cleaning techniques, Preferred flow patterns, Economics.