LegioSafe – Legionella in hot water systems

SPF has carried out three projects from 2017 – 2020 on the topic of Legionella in hot water systems. In the LegioSafe project (2018), a literature study was conducted on legionella, temperatures in drinking water systems, and the occurrence of legionella in systems with solar thermal water heating. In 2019, a field study was conducted including 110 buildings in «LegioSafeCheck». More than 300 shower water samples and over 100 samples from the lower area of heat water tanks were taken and analysed for Legionella. One year later, in the project LegioSafePlus, exclusively buildings in which legionella > 1000 CFU/L were found in at least one shower water sample in 2019 were further monitored and re-sampled. The results were made available for the standardisation work of SIA 385/1:2020 and are described in three final reports. Results of both field studies were summarised in an article published in «hk gebäudetechik». Due to installation deficiencies identified in the field, a leaflet on the correct combination of hot water circulation and central cold water admixture was produced with the help of suissetec, GKS and Swissolar as well as EnergieSchweiz.