Risk-Based Evaluation of Improvements in DrinkingWaterTreatment Using Cost-Benefit Analysis

Reliable and safe drinking water supply requires adequate risk management. Decisionsupport models can aid decisionmakers to effectively evaluate risk mitigation measures and allocatesocietal resources. Here, a Swedish case study illustrates how the installation of ultrafiltrationmembranes can be evaluated by combining risk assessment and cost-benefit analysis. Quantitativemicrobial risk assessment was used to assess several contamination sources and estimate the achievedrisk reduction from waterborne pathogens using Campylobacter, Norovirus, and Cryptosporidiumas reference pathogens. The societal value of the improved water quality was estimated in thecost-benefit analysis by monetising the gained quality adjusted life years and aesthetic water qualityimprovements. The calculated net present value (mean of 7 MEUR) indicated that the installation ofthe ultrafiltration membranes was a sound investment from a societal economic perspective. Theultrafiltration membranes reduced the annual probability of infection from 3x10-2 to 10-7, wellbelow 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 onlyhealth-related metrics when evaluating treatment options or monitoring the drinking water quality,but to also consider the aesthetic quality of the drinking water.