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Research Group Issues Updated UV Guidelines

The National Water Research Institute (NWRI), in collaboration with the Water Research Foundation, has published an update to their Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse. The guidelines are intended to provide guidance to state and federal regulatory agencies who review applications for the use of ultraviolet (UV) disinfection systems in drinking water and water reuse, and to water utilities who are interested in using UV for disinfection purposes. These guidelines are meant to provide a common basis for evaluating and implementing UV disinfection technologies. They will also provide a methodology that can be used to validate UV disinfection system performance. As a minimum, under these guidelines manufacturers are required to demonstrate the efficacy of their equipment. When testing is complete, the results shall be summarized in a report. This performance-based testing approach is directed toward quantifying the inactivation of target microorganisms (i.e., MS-2 bacteriophage) by UV equipment.

These guidelines are a third revision of the Guidelines for Drinking Water published by NWRI. Revisions to the UV guidelines were made to reflect experience gained from the application of the guidelines in a variety of situations. The NWRI is a research group founded in 1991 by a number of California water agencies. These guidelines are largely based on the current practice of the California Department of Public Health (CDPH) in their review and approvals of UV disinfection systems. These guidelines have not been developed to describe average UV disinfection performance, but rather the minimum performance expected of a UV disinfection system. The Guidelines include chapters on:

  • UV Dose
  • Reactor Design
  • Reliability Design
  • Monitoring and Alarm Design
  • Field Commissioning Test
  • Performance Monitoring
  • Engineering Report

These guidelines, along with EPA’s Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced Surface Water Treatment Rule can provide states with more technical background as they evaluate UV disinfection projects. The Guidelines are available for download on the NRWI website.