Sterilight ultraviolet water sterilizers incorporate natural ultraviolet light energy to eradicate microbiological contamination. Sterilight Protects Water Natures Way... Water enters through the bottom port of the ultraviolet reactor chamber and swirls around a low pressure mercury vapour lamp thermally protected by a quartz sleeve. The UV lamp emits powerful ultraviolet light energy at a wavelength of 253.7 nm. Vital genetic components contained in microorganisms absorb the light energy; this disrupts the DNA and prevents reproduction. Treated water then exits through the top port of the generator cell and is ready for consumption.