The fully automated Colifast ALARM^TM has been used for two years for daily monitoring of the presence/absence of Escherichia coli in 100 mL raw water at Oset drinking water treatment plant in Oslo, Norway. The raw water is extracted from 35 m depth from the Lake Maridalsvannet. E. coli was detected in 18% of the daily samples. In general, most samples positive for E. coli were observed during the autumn turnover periods, but even in some samples taken during warm and dry days in July, with stable temperature stratification in the lake, E. coli was detected. The daily samples gave useful additional information compared with the weekly routine samples about the hygienic raw water quality and the hygienic barrier efficiency of the lake under different weather conditions and seasons. The winter 2013/2014 was much warmer than the winter 2012/2013. The monitoring supported the hypothesis that warmer winters with shorter periods with ice cover on lakes, which may be a consequence of climate changes, may reduce the hygienic barrier efficiency in deep lakes used as drinking water sources.

We describe the different length (DL) qPCR method for quantification of UV induced DNA damage in cell killing. The principle of DL qPCR is that DNA damage inhibits PCR. Applications with different lengths can therefore be used to detect different levels of UV-induced DNA damage. The assay was evaluated on three strains of Escherichia coli exposed to varying levels of ultraviolet (UV) radiation. We show that DL qPCR sensitivity and reproducibility are within the range of practical application to detect the effect of UV cell killing.

Surface water is used for irrigation of food plants all over the World. Such water can be of variable hygienic quality, and can be contaminated from many different sources. The association of contaminated irrigation water with contamination of fresh produce is well established, and many outbreaks of foodborne disease associated with fresh produce consumption have been reported. The objective of the present study was to summarize the data on fecal indicators and selected bacterial pathogens to assess the level of fecal contamination of a Norwegian river used for irrigation in an area which has a high production level of various types of food commodities. Sources for fecal pollution of the river were identified. Measures implemented to reduce discharges from the wastewater sector and agriculture, and potential measures identified for future implementation are presented and discussed in relation to potential benefits and costs. It is important that the users of the water, independent of intended use, are aware of the hygienic quality and the potential interventions that may be applied. Our results suggest that contamination of surface water is a complex web of many factors and that several measures and interventions on different levels are needed to achieve a sound river and safe irrigation.

Simple, automated methods are required for rapid detection of wastewater contamination in urban recreational water. The activity of the enzyme β-d-galactosidase (GAL) can rapidly (5 LOG₁₀. Furthermore, the GAL-activity per gram feces from birds, sheep and cattle was 2–3 LOG₁₀ lower than the activity from human feces, indicating that high GAL-activity in water may reflect human fecal pollution more than the total fecal pollution. The rapid method can only be used to quantify high levels of human fecal pollution, corresponding to about 0.1 mg human feces/liter (or 10³ E. coli/100 mL), since below this limit GAL-activity from non-fecal environmental sources may interfere.

Information about the concentration, growth and decay rates of microorganisms in different water sources is crucial for development of quantitative microbial risk assessment (QMRA). There is little or no such information at regional level and little is known about the microbial decay rates at different depths of the marine environment. This study was conducted to investigate the density of faecal indicator bacteria (FIB) in different wastewater conveyance systems, the potential for microbial growth in greywater, and the decay rate of indicator bacteria and pathogenic viruses in seawater samples from different depths. The average concentration (log10 per 100 ml) of Escherichia coli (E. coli) and intestinal enterococci (IE) were 6.7 and 6.1 in blackwater, 6.1 and 3.8 in greywater, and 6.6 and 5.2 in municipal wastewater, respectively. Total coliforms (TC) and E. coli multiplied in greywater for the first 24 hours. Indicator bacteria and viruses were rapidly inactivated at 20 oC in surface seawater, but at 4 oC in deep seawater the infectivity was kept, to a certain degree. Our results indicate that temperature and biological activity of surface seawater are important factors for the decay rate of indicator bacteria and virus.