What is good disinfection practice?

Since the early nineteen hundreds, chlorine has been applied to disinfect drinking water. However, chlorination has its constraints and research has demonstrated a prevailing risk from pathogens such as viruses and protozoa, which have proved to be partly resistant to chlorine, which promotes the concept of a multi-barrier protection. Consequently, more advanced technologies and operation procedures potentially have to be implemented in our Water Treatment Plants. New Zealand consists of many small to medium sized communities, which is also the case for Scandinavia, and as such, is comparable with Sweden. The prevailing risk of protozoa and viruses encouraged Water BA and Swedish Water AB to support a study on Good Disinfection Practice. The objective was to get an understanding of disinfection practices in different countries and to develop a pragmatic approach to a good disinfection practice for the conditions in Scandinavia. The study resulted in a proposed model based on a microbiological multi-barrier approach, considering the water safety from source to tap in terms of removal requirements for bacteria, protozoa and viruses. This paper presents findings in the report and guideline, and the developed model, and compares the approach to the New Zealand Drinking Water Standards 2005 (rev 2008).