In the third edition of the Guidelines for Drinking-water Quality, the World Health Organization concludes that an integrated management of risks in source waters, treatment systems and distribution networks is the most effective way to guarantee safe drinking water to consumers. The integrated approach is fundamental to avoid sub-optimisation of risk-reduction measures. This paper presents an application of an integrated and quantitative risk model for comparing risk-reduction measures to support decisions for reaching specified water safety targets. A fault tree approach is used for structuring the risk analysis and for estimating the risk, expressed as Customer Minutes Lost (CML). Input information is a combination of hard data and expert judgements. Uncertainties in input information are considerable and modelled by a Bayesian statistical approach. A drinking water system in Sweden is used to exemplify model application. Quantitative safety targets have been confirmed at the political level as a basis for long-term planning of investments and reinvestments. One target defines an acceptable risk level of 144 annual CML for the average consumer. For the current system structure an estimated risk of 612 CML was obtained. Four risk-reduction alternatives were compared and they reduce the risk to between 50 and 81 CML, i.e. below the acceptable level. The paper describes how a structured and thorough analysis of risk-reduction measures can facilitate transparency and long-term planning of drinking water systems.
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Research Article|
July 01 2010
Comparing risk-reduction measures to reach water safety targets using an integrated fault tree model
L. Rosén;
1Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden E-mail: lars.rosen@chalmers.se; andreas.lindhe@chalmers.se; thomas.pettersson@chalmers.se
E-mail: lars.rosen@chalmers.se
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A. Lindhe;
A. Lindhe
1Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden E-mail: lars.rosen@chalmers.se; andreas.lindhe@chalmers.se; thomas.pettersson@chalmers.se
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O. Bergstedt;
O. Bergstedt
2Göteborg Vatten, Box 123, SE-424 23 Angered, Sweden E-mail: olof.bergstedt@vatten.goteborg.se
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T. Norberg;
T. Norberg
3Department of Mathematical Sciences, Göteborg University and Chalmers University of Technology, SE-412 96 Göteborg, Sweden E-mail: tommy@chalmers.se
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T. J. R. Pettersson
T. J. R. Pettersson
1Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden E-mail: lars.rosen@chalmers.se; andreas.lindhe@chalmers.se; thomas.pettersson@chalmers.se
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Water Supply (2010) 10 (3): 428–436.
Citation
L. Rosén, A. Lindhe, O. Bergstedt, T. Norberg, T. J. R. Pettersson; Comparing risk-reduction measures to reach water safety targets using an integrated fault tree model. Water Supply 1 July 2010; 10 (3): 428–436. doi: https://doi.org/10.2166/ws.2010.089
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L. Rosén, A. Lindhe, O. Bergstedt, T. Norberg, T. J. R. Pettersson; Comparing risk-reduction measures to reach water safety targets using an integrated fault tree model. Water Supply 1 July 2010; 10 (3): 428–436. doi: https://doi.org/10.2166/ws.2010.089
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