Accounting for Unexpected Risk Events in Drinking Water Systems
Journal article, 2020

Unexpected risk events in drinking water systems, such as heavy rain or manure spill accidents, can cause waterborne outbreaks of gastrointestinal disease. Using a scenario-based approach, these unexpected risk events were included in a risk-based decision model aimed at evaluating risk reduction alternatives. The decision model combined quantitative microbial risk assessment and cost–benefit analysis and investigated four risk reduction alternatives. Two drinking water systems were compared using the same set of risk reduction alternatives to illustrate the effect of unexpected risk events. The first drinking water system had a high pathogen base load and a high pathogen log10 reduction in the treatment plant, whereas the second drinking water system had a low pathogen base load and a low pathogen Log10 reduction in the treatment plant. Four risk reduction alternatives were evaluated on their social profitability: (A1) installation of pumps and back-up power supply, to remove combined sewer overflows; (A2) installation of UV treatment in the drinking water treatment plant; (A3) connection of 25% of the OWTSs in the catchment area to the WWTP; and (A4) a combination of A1–A3. Including the unexpected risk events changed the probability of a positive net present value for the analysed alternatives in the decision model and the alternative that is likely to have the highest net present value. The magnitude of the effect of unexpected risk events is dependent on the local preconditions in the drinking water system. For the first drinking water system, the unexpected risk events increase risk to a lesser extent compared to the second drinking water system. The main conclusion was that it is important to include unexpected risk events in decision models for evaluating microbial risk reduction, especially in a drinking water system with a low base load and a low pathogen log10 reduction in the drinking water treatment plant.

Risk management

Cost–benefit analysis (CBA)

Quantitative microbial risk assessment (QMRA)

Water quality modelling

Decision support

Dose–response

Author

Viktor Bergion

Chalmers, Architecture and Civil Engineering, GeoEngineering

Andreas Lindhe

Chalmers, Architecture and Civil Engineering, GeoEngineering

Ekaterina Sokolova

Chalmers, Architecture and Civil Engineering, Water Environment Technology

Lars Rosen

Chalmers, Architecture and Civil Engineering, GeoEngineering

Exposure and Health

2451-9766 (ISSN) 2451-9685 (eISSN)

Vol. In Press

Subject Categories

Water Engineering

Water Treatment

Oceanography, Hydrology, Water Resources

DOI

10.1007/s12403-020-00359-4

More information

Latest update

6/29/2020