Ultraviolet radiation is rather a common method in Norway for disinfection of drinking water.
The development of highly efficient water radiation units in recent years has made UV disinfection reliable and economically competitive. Today, Norway is among the leading nations in applying UV disinfection of drinking water. Both systems are accepted for drinking water disinfection in Norway. This evaluation, which has been going on since the early 70ies, shall guarantee that all UV units at Norwegian water works meet a certain standard. A type approval includes a calculation of the capacity of each UV system.