Abstract
Reliable and safe drinking water supply requires adequate risk management. Decision support models can aid decisionmakers to effectively evaluate risk mitigation measures and allocate societal resources. Here, a Swedish case study illustrates how the installation of ultrafiltration membranes can be evaluated by combining risk assessment and cost-benefit analysis. Quantitative microbial risk assessment was used to assess several contamination sources and estimate the achieved risk reduction from waterborne pathogens using Campylobacter, Norovirus, and Cryptosporidium as reference pathogens. The societal value of the improved water quality was estimated in the cost-benefit analysis by monetising the gained quality adjusted life years and aesthetic water quality improvements. The calculated net present value (mean of 7 MEUR) indicated that the installation of the ultrafiltration membranes was a sound investment from a societal economic perspective. The ultrafiltration membranes reduced the annual probability of infection from 3 × 10−2 to 10−7, well below the U.S. EPA’s acceptable level, as well as improving the aesthetic quality of the drinking water. The results provide a novel example of the importance for water distributors to consider not only health-related metrics when evaluating treatment options or monitoring the drinking water quality, but to also consider the aesthetic quality of the drinking water.
Highlights
water safety plans (WSPs) is meant to be implemented as part of a comprehensive risk management approach, including an assessment of the drinking water system’s sub-systems, the raw water source, the drinking water treatment plant (DWTP), and the supply network [11,12]
The health-related risk reduction of the installed UF membrane (Ultrafiltration membrane: X-flow Aquaflex 55) at Kvarnagården DWTP was estimated using Quantitative microbial risk assessment (QMRA) and quantified in terms of number of reduced infections and gained quality adjusted life years (QALYs) per year. The latter was monetised and analysed, in combination with aesthetic quality improvements and costs, in a cost benefit analysis (CBA), in order to determine if the installation of the UF membranes was societally profitable
The results show the importance of having a holistic approach when assessing the societal economic value of improvements in drinking water treatment
Summary
Received: 15 December 2021Good decisions, or rather good outcomes, are always sought after in any decisionmaking process. In more complex fields, the formation of good decision often requires a deeper form of analysis [1,2]. One such field is the management and handling of risk [3–5]. Has suggested an iterative risk management approach that involves the assessment and possible treatment of risks, as well as a continuous communication and monitoring of the process [6]. The World Health Organisation (WHO) suggests the use of comprehensive and holistic approaches, e.g., water safety plans (WSPs), to ensure a safe and reliable supply of drinking water [10]. WSP is meant to be implemented as part of a comprehensive risk management approach, including an assessment of the drinking water system’s sub-systems, the raw water source, the drinking water treatment plant (DWTP), and the supply network [11,12]
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