# Operation of Water Supply Systems in the Czech Republic--Risk Analysis
## 2 Materials and Methods  
The strengths and weaknesses of the most frequently used operating models of water supply systems in the Czech Republic were evaluated using the IFE (internal factors evaluation) matrix [13]. The IFE matrix is a tool to reveal a company's strengths as well as weaknesses. It is recommended that the matrix be symmetrical, i.e., it includes an equal number of strengths and weaknesses. Each factor should be assigned a weight ranging from 0.00 (low importance) to 1.0 (high importance). The sum of the weights of the strengths and weaknesses must equal one. In addition, each factor must be assigned a 1 to 4 rating to indicate the level of weakness and strength: 4--significant strength, 3--less significant strength, 2--less significant weakness, and 1--significant weakness. By multiplying the weight and the rating, we obtain an overall weighted score on the basis of which the final assessment is performed. The weighted score is simply the sum of all individual scores, with the best possible score being 4.00, while the worst possible score is 1.00. Risk analysis methods used in water supply systems are discussed, for example, in the study by [PERSON] et al. [14]. In our study, we decided to use the FMEA method for risk analysis, as FMEA (failure mode and effect analysis) is one of the most widely used methods of expert analysis [12; 14]. It is a structured reliability analysis, identifying potential system failures and their causes and consequences. The FMEA method is considered an effective risk analysis method allowing us to recognize potential failures at different stagesand to determine possible consequences to evaluate the risks and ways of prevention. It also serves as an early warning method. The expert group selected representatives representing different operating models for which the FMEA risk analysis was performed. The level of risk was rated on a scale of 1 (Insignificant risk) to 5 (Critical risk) according to the severity of the consequence of the risk (Table 2). The probability of the risk incidence (Table 3) was rated on a scale of 1 (Unlikely) to 5 (Very high). The ability of detection (Table 4) was also rated on a five-point scale of 1 (Almost certainly detectable) to 5 (Absolute uncertainty). The risk priority number (RPN) index was determined as the multiplication of the significance, incidence, and probability of risk. A flowchart of the proposed FMEA model is illustrated in Figure 1. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Risk Detectability** & **Probability of Detection** & **Grade** \\ \hline Absolute uncertainty & The risk is unpredictable & 5 \\ \hline Low & The risk is hard to predict & 4 \\ \hline Moderate & The probability of risk detection is hard to predict. & 3 \\ \hline High & High probability of risk detection, there are standard procedures in place to monitor and detect risk. & 2 \\ \hline Almost certain & Very high probability of detecting the risk using standard control mechanisms. & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Risk detectability (own source). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Level of Risk** & **Criteria of the Severity of the Consequence** & **Grade** \\ \hline \multirow{3}{*}{Critical} & Very high severity threatening the entire process with critical consequences for end users, significant threats to water quality or taking the entire system out of service. & 5 \\ \hline Highly severe & Very serious risk, possibility of threat to water supply system. & 4 \\ \hline Severe & Moderate risk, possibility of partial impact on the system. & 3 \\ \hline Low & Low risk, no serious threat to the water supply system or water quality. & 2 \\ \hline \multirow{2}{*}{Insignificant} & Insignificant risk, does not threaten continuous water supply or water quality. & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Level of risk (own source).