The Q&A session for this topic is Q&A 3: Microbiological Contamination and Treatment.
NSF International recently issued an important update to NSF/ANSI 55 – Ultraviolet Microbiological Water Treatment Systems. Historically, only treatment systems using a low-pressure mercury lamp were able to be certified. A new test method has been developed for alternative UV sources, including LED diodes, allowing certification of systems emitting UV light across the entire range of 240 nm to 300 nm. This new method requires 4.0 log inactivation of the Qβ coliphage virus for a Class A certification, or 2.14 log inactivation of the virus for a Class B certification. This new test method provides an important means of validating new alternative UV systems as they become more commonplace in the market.