After filtration, the water is exposed to a UVC light source which inactivates pathogens. Amongst the advantages of this method is that there are no toxic chemicals involved in the treatment which may cause a hazard to the environment and to those handling them.

A flow UVC sterilizer is installed between the filtration group and the holding tank. The flow rate in the raw-water circuit is adapted to the power of the UVC-lamp to insure that irradiation is sufficient to deactivate all pathogens. The wavelength of the UVC light source, 254nm, is close to the characteristic dimension of the DNA of the pathogens. A further UVC light source is installed in the holding tank to make sure there is no re-contamination of the water that has been treated previously. Both UVC sources are checked by a sensor, raising an alarm in case one of them has become defective

An Ozone generator can be added to the drinking water circuit, adding additional security. Local regulations or consumer habits may require the addition of a defined dose of chlorine to the water. A chlorine dispenser can be added to the system; however, in this case adequate training in handling hazardous chemical of the operators and the maintenance personnel is required.