The objective of the focus action was to collect data on the extent to which undissolved substances such as clay, iron, etc. can have an influence on the disinfection performance in drinking water treatment. 134 UV disinfection plants from all over Austria were inspected:

• One sample was unsuitable for human consumption due to microbiological contamination. The sample came from a non-certified UV system that was apparently out of order.
• In four plants, the microbial content of the samples was slightly elevated.

Turbidity of drinking water is caused by undissolved substances such as clay, soil, plant material, manganese, iron, but also by microorganisms. Turbidity can reduce disinfection performance because microorganisms attached to particles or protected in aggregates are not directly exposed to disinfectants.