Using the CyFlow flow cytometer from Partec, it is possible to rapidly determine the microbiological status of drinking water. The procedure can be carried out at water companies, in distribution networks and at end consumers. Mobile testing is also possible.

The technique, called "Determination of total cell count and the quantitative relationship between cells with low and high nucleic acid content in fresh water by means of flow cytometry', is quick, reliable and cost-effective. It enables bacterial contamination in drinking water to be characterised in less than 15 minutes and has been added to the Swiss Federal Office of Public Health's Food Codex as a recommended technique. In addition to time-consuming conventional routine checks, water companies and cantonal and state analytical laboratories now have access to an innovative technique able to be used as an early warning parameter or for ongoing monitoring. A pilot system for online microbial monitoring has already been implemented at a waterworks operated by the City of Zürich.

The driving force behind the new development is the Environmental Microbiology Department at the Swiss Federal Institute of Aquatic Science and Technology (Eawag). After several years of experimental work, researchers from Eawag supported by Partec with dedicated equipment for small particle counting have succeeded in using flow cytometry. The technique involves marking individual bacterial cells with a fluorescent marker and using fluorescence detection to count and characterise them in a laser beam. A stand-out feature of the technique is its ability to count large numbers of bacteria in just a few seconds. By analysing samples in an automated unit (e.g. the CyFlow flow cytometer from Partec), it is possible to process more than 50 separate water samples per hour.

Partec has also realised the technical adaptation of its analytical instruments to meet the needs of mobile and online drinking water quality checks. As part of an Eawag project sponsored by the Berne-based Commission for Technology and Innovation CTI, the technique has been validated by an alliance of 14 Swiss and German institutions, including water companies, public and private analytical laboratories and research institutes. The technique has recently been awarded the status of a standard operating procedure in Switzerland's Food Codex.