Regulations in the United States: requirements and guidance for ultraviolet disinfection of drinking water

In July 2003, the US Environmental Protection Agency (USEPA) published a proposed regulation, the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), which included requirements pertaining to ultraviolet (UV) disinfection. In addition the USEPA released the proposed UV Disinfection Guidance Manual (UVDGM) that provides implementation guidelines for UV disinfection. Since July 2003, USEPA has revised several elements, which are also described. This paper summarizes proposed regulatory requirements in the United States (US) that pertain to disinfection of drinking water using UV light and the recommendations in USEPA's UVDGM. Although this paper does not provide the detailed UVDGM recommendations, it highlights important elements of the proposed regulation and guidance, including required UV doses, UV facility design and operation, and UV reactor validation. The US regulations and guidance do not directly affect the implementation of UV facilities in other countries; however, the information provided in this paper provides a different perspective for worldwide facilities and regulatory agencies to consider.