The role of rapid E.coli monitoring and selected surrogate parameters for managing short-term contamination episodes in the Spree Canal of Berlin

As part of the international project Digital Water City (DWC), a water quality monitoring campaign was carried out by the research institute KompetenzzentrumWasser Berlin (KWB) in the Spree Canal during the summer of 2020. The Spree Canal is a sidearm of the river Spree and receives discharges of Berlin’s combined sewer system overflows. The association Flussbad e.V. investigates actions to make this water section usable as bathing water since in its current state the Spree Canal is under high hygienic pressure after heavy rainfall. The aim of this study was to monitor the presence of E.coli as indicator organism for faecal contaminations in the urban water. For this purpose a mobile and an in-situ deployed rapid E.coli measuring device by the company Fluidion SAS were tested in the field as well as under controlled laboratory conditions: the ALERT Lab and the ALERT System. The devices were evaluated regarding their detection of faecal contamination and their suitability to be used as a supplement or replacement for the more time-consuming Most Probable Number (MPN) reference method according to DIN EN ISO 9308-3 (1998) which is required by the EU-Directive 2006/7/EC (2006). The evaluation criteria included the agreement of the measurement results with the MPN reference method as well as the measurement precision of the devices. The ALERT Lab was able to achieve precisions comparable to the MPN method, but the results also revealed a systematic overestimation of the MPN reference. The ALERT System on