Solving incidents with contaminated drinking water using hydraulic modelling
During 2017, two incidents with coliform bacteria in the drinking water occurred in Lund, South Sweden. Boil water advisories were issued and the extensive work began to limit the affected areas, find the sources of contamination and restore the network to normal conditions. During both incidents, hydraulic modelling was used as part of the trace methodology for detection of the sources of the microbiological contaminations. This proved to be an essential tool in which the theoretical distributions from different source scenarios were compared to the results from water analysis. The model was also used to reduce the areas with boil water advisories. In incident no 1, the coliform bacteria were typed as Erwinia spp. Lab results later showed that the recovered source of contamination consisted of wheat flour; which had been put in the pipe during an installation work four months earlier. In incident no 2, the source also consisted of organic matter (paper napkin) left in a pipe after an installation work. The coliforms found on the organic matter were typed as Serratia spp.