Ultraviolet Light Disinfection in the Use of Individual Water Purification Devices

Understanding the disinfection capabilities of UV light to inactivate disease-causing microorganisms is important in protecting Soldiers, who are considering using this technology, from acute health threats posed by these microorganisms. Soldiers deployed beyond traditional field drinking water supplies must have access to microbiologically safe water. Using IWPDs is one way to provide microbiologically safe water in these situations. These IWPDs must protect the Soldier from acute microbial health threats. The U.S. Environmental Protection Agency (EPA) Guide Standard and Protocol for Testing Microbiological Water Purifiers (reference 1) provides performance standards by which an IWPD that uses UV light can be evaluated. The performance standards are a minimum 6-log reduction/inactivation of bacteria, 4-log reduction/inactivation of viruses, and 3-log reduction/inactivation of protozoan cysts. UV-using IWPDs meeting these standards are considered effective against disease causing bacteria, viruses, and protozoan cysts. Some IWPD manufacturers test their devices using this protocol. This is the best way to evaluate the IWPDs disinfection capabilities. In the absence of that testing data, this information paper can be used to gain an understanding of UV light disinfection capabilities and help determine if an IWPD using UV light could successfully meet the EPA Guide’s minimum performance standards. This information paper was developed primarily using information obtained from the EPA’s Draft Ultraviolet Disinfection Guidance Manual (reference 2). The manual provides a comprehensive review of available scientific literature concerning UV disinfection in drinking water systems.