Stochastic modelling of drinking water treatment in quantitative microbial risk assessment

“Drinking water outbreaks of infectious disease in the twentieth and twentyfirst centuries made clear that the absence of indicator organisms did not guaranty that the drinking water was safe. The World health organization (WHO) has developed the Water Safety Plan (WSP) approach to address the shortcomings of the indicator principle. The WSP aims to achieve safe drinking water by adequate control of drinking water sources, treatment and distribution. The ability of the total system to provide safe drinking water and the required activities to verify that safe water is provided are assessed in the WSP. Since conditions can vary between individual systems, site specific studies are required to assess the safety of a drinking water system. In addition, it has become clear that very short periods of unsafe water can have a major impact on the (mean) risk of infection from drinking water. Quantitative microbial risk assessment (QMRA) was developed to assess the level and variability of the health risk and can include the uncertainty involved in the assessment. It is therefore logical to apply QMRA in the WSP at points where risks need to be quantified.”

(Citaat: Smeets, P.W.M.H. – Stochastic modelling of drinking water treatment in quantitative microbial risk assessment)