AWWA ACE60081

The water industry has been conducting vulnerability assessments of critical water infrastructure. These assessments produce outputs that will prompt some tough expenditure decisions. In an industry already faced with the combined costs of increasingly stringent regulations, infrastructure replacement, water shortages, and competitive pressures, how much is it prudent to spend on long lists of increased security measures to combat unknowable risks? Doubts about our safety have been raised and these doubts need to be addressed. Yet, it is difficult to put such doubts to rest when we cannot reliably quantify the risks. Regrets analysis is a decision technique devised specifically for situations where it is not possible to quantify the risk. Regrets analysis focuses instead on what we do know. We know a lot about the specific threats that we have defined and about the level and criticality of damage that is possible. We know the costs of alternative actions we can take to reduce the risk of such threats materializing. We know something about the comparative effectiveness of alternative actions in reducing risks or mitigating effects. Looking across all combinations of costs and scenarios, regrets analysis determines which choice has the least chance of being the worst choice over all possibilities. In other words, it shows how you can minimize your potential regrets. This paper presents an example of regrets analysis applied to a security improvement decision regarding the protection of a chlorine tank from possible sabotage. The analysis is developed in a spreadsheet and the following narrative describes the input data required and the analytical steps involved. Includes tables.