Identification and management of microbial contaminations in a surface drinking water source

Åström, Johan; Pettersson, Thomas; Stenström, Thor Axel

doi:10.2166/wh.2007.137

Cited by 20 publications

(7 citation statements)

References 27 publications

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“…The culture analysis indicated higher concentrations of coliforms and E. coli in samples collected in colder water. These findings are corroborated by other studies in countries with more temperate climate where higher concentrations of coliforms correlated positively with cold water and high rainfall [7] and cold water and high conductivity [64]. Bacteria measured by culture methods (coliforms, E. coli and C. perfringens) ( Figure 3) were efficiently reduced by the artificial infiltration, while ssrA DNA copies from real-time PCR analysis were detected in similar concentrations both before and after the artificial infiltration, indicating that the ssrA DNA were transported through the infiltration or that there were additional sources impacting the infiltrated water.…”

Section: Discussionsupporting

confidence: 88%

“…However, in most countries with developed water supply systems, increased levels of contamination are often linked to failures in water piping systems or drinking water treatment plants [5,6]. Storms and heavy rainfalls resulting in discharges of wastewater and runoff from livestock or wildlife into rivers and lakes can also increase microbial contamination [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Molecular Analyses of Fecal Bacteria and Hydrodynamic Modeling for Microbial Risk Assessment of a Drinking Water Source

Chuquimia

Bergion

Guzman-Otazo

et al. 2019

Water

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Safe water is a global concern, and methods to accurately monitor quality of water are vital. To assess the risks related to bacterial pathogen load in Lake Vomb that provides drinking water to the southern part of Sweden, this study combined molecular analyses of enterobacteria and bacterial pathogens in water using quantitiative real-time PCR with hydrodynamic modeling and quantitative microbial risk assessment (QMRA). A real-time PCR assay to detect enterobacteria was set up by primers targeting ssrA. Between February 2015 and May 2016, presence of ssrA gene copies as well as Campylobacter spp., Salmonella spp., and EHEC O157 DNA was analyzed by real-time PCR at several locations in the catchment of Lake Vomb and its tributaries Björkaån, Borstbäcken, and Torpsbäcken. Björkaån had the highest detected concentrations of the ssrA gene and, according to the results of hydrodynamic modeling, contributed most to the contamination of the water intake in the lake. None of the water samples were positive for genes encoding EHEC O157 and Campylobacter spp., while invA (Salmonella spp.) was present in 11 samples. The QMRA showed that the suggested acceptable risk level (daily probability of infection <2.7 × 10 −7 ) is achieved with a 95% probability, if the Salmonella concentrations in the water intake are below 10 1 bacteria/100 mL. If a UV-disinfection step is installed, the Salmonella concentration at the water intake should not exceed 10 6 bacteria/100 mL.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Molecular Analyses of Fecal Bacteria and Hydrodynamic Modeling for Microbial Risk Assessment of a Drinking Water Source

Chuquimia

Bergion

Guzman-Otazo

et al. 2019

Water

View full text Add to dashboard Cite

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“…In addition to such situations, sewage overflows are common. The study bẙ Aström et al (2007) clearly indicated a relationship between turbidity, precipitation, and e-coli, where e-coli was representing the release of bacteria from pasture land and sewage overflows.…”

Section: Discussionmentioning

confidence: 92%

Variation in turbidity with precipitation and flow in a regulated river system – river Göta Älv, SW Sweden

Göransson

Larson

Bendz

2013

Hydrol. Earth Syst. Sci.

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Abstract. The turbidity variation in time and space is investigated in the downstream stretch of the river GötaÄlv in Sweden. The river is heavily regulated and carries the discharge from the largest fresh water lake in Sweden, Lake Vänern, to the outflow point in Göteborg Harbour on the Swedish west coast. The river is an important waterway and serves as a fresh-water supply for 700 000 users. Turbidity is utilised as a water quality indicator to ensure sufficient quality of the intake water to the treatment plant. The overall objective of the study was to investigate the influence of rainfall, surface runoff, and river water flow on the temporal and spatial variability of the turbidity in the regulated river system by employing statistical analysis of an extensive data set. A six year long time series of daily mean values on precipitation, discharge, and turbidity from six stations along the river were examined primarily through linear correlation and regression analysis, combined with nonparametric tests and analysis of variance. The analyses were performed on annual, monthly, and daily bases, establishing temporal patterns and dependences, including; seasonal changes, impacts from extreme events, influences from tributaries, and the spatial variation along the river. The results showed that there is no simple relationship between discharge, precipitation, and turbidity, mainly due to the complexity of the runoff process, the regulation of the river, and the effects of Lake Vänern and its large catchment area. For the river GötaÄlv, significant, positive correlations between turbidity, discharge, and precipitation could only be found during periods with high flow combined with heavy rainfall. Local precipitation does not seem to have any significant impact on the discharge in the main river, which is primarily governed by precipitation at catchment scale. The discharge from Lake Vänern determines the base level for the turbidity in the river, whereas local surface runoff and tributary discharge induced by rainfall govern the temporal variability in turbidity. Autocorrelation analysis indicates a temporal persistence in turbidity of about 10 days. The results also show that erosion along the main river, from the river bed and banks, is not a dominant contributor to the suspended sediment transport in the river under normal conditions. Further studies on the correlation between turbidity and suspended sediment transport and its relation to erosion processes are suggested.

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“…A recent review concluded that "the value of sanitary inspection is not derived from its ability to predict risks to water quality, but from its utility in the ongoing effort to protect water safety" [9]. Therefore, the published SI forms cannot be considered a substitute for direct water quality sampling, but rather a complementary activity for effective management of water supply systems [14,20].…”

Section: Introductionmentioning

confidence: 99%

Combining Sanitary Inspection and Water Quality Data in Western Uganda: Lessons Learned from a Field Trial of Original and Revised Sanitary Inspection Forms

et al. 2020

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Risk assessment for drinking water systems combines sanitary inspections (SI) and water quality testing and is critical for effectively managing the safety of these systems. SI forms consist of question sets relating to the presence of potential sources and pathways of contamination specific to different types of water points, piped distribution systems, and household collection and storage practices. As part of the revision to the Guidelines for Drinking-water Quality (GDWQ), the World Health Organization (WHO) is updating the suite of SI forms to reflect and include the most recent technical and scientific information available. This paper reports the results from a field pilot of a selection of published and revised SI forms and water quality testing in the municipality of Bushenyi-Ishaka, Uganda. We collected data from 45 springs, 61 taps from piped distribution systems, and 129 household storage containers filled with water from those springs and taps. The median total risk scores, according to the revised forms, for spring, tap, and household practices were 36, 53, and 33%, respectively, with higher percentages indicating greater risk. The median Escherichia coli concentrations of spring, tap, and household storage systems were 17, <1, and 7 CFU/100 mL, respectively. We found that increased questioning in the revised SI forms do not necessarily translate to a higher total risk. There is potential for misinterpretation of terminology in the revised SI forms and occasional redundancy of concepts. For the revised SI form for springs, we suggest specific text changes to reduce potential bias. We recommend that users of SI forms receive training in their use and be familiar with their locale. Furthermore, the revised SI forms may need to be adapted in accordance with the local context.

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Identification and management of microbial contaminations in a surface drinking water source

Cited by 20 publications

References 27 publications

Molecular Analyses of Fecal Bacteria and Hydrodynamic Modeling for Microbial Risk Assessment of a Drinking Water Source

Molecular Analyses of Fecal Bacteria and Hydrodynamic Modeling for Microbial Risk Assessment of a Drinking Water Source

Variation in turbidity with precipitation and flow in a regulated river system – river Göta Älv, SW Sweden

Combining Sanitary Inspection and Water Quality Data in Western Uganda: Lessons Learned from a Field Trial of Original and Revised Sanitary Inspection Forms

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