Ultraviolet Can Be Used to Reduce Chlorine and Chloramines

As a footnote to a recent article we published about removing chloramines with ultraviolet, here is a quote from water treatment expert David Bauman, writing in Water Technology:
Ultraviolet (UV) treatment is another dechlorination alternative.

UV is often promoted as a pretreatment method for reverse osmosis (RO), to reduce chlorine that could degrade certain RO membranes.

An advantage of UV, as with certain activated carbons, is that it can reduce both free chlorine and combined chlorine compounds (chloramines). At the right wavelengths, the UV light dissociates chlorine in water to form hydrochloric acid. Or, to phrase it in a less negative way, hydrogen and chloride ions are formed.

Different peak wavelengths have been published for dissociation of free chlorine, so a UV manufacturer would have to be consulted. Manufacturers say that up to 15 parts per million (ppm) of free chlorine can be removed.

The UV dosage required for dechlorination depends on total chlorine level, ratio of free versus combined chlorine, background level of organics, and the desired reduction level.

To our knowledge, there are no residential UV systems yet on the market for chloramine reduction.