Risk Assessment of Drinking Water Supply System of Talesh Based on World Health Organization Water Safety Plan in 2021: A Case Study

Water safety plan (WSP) is a new way to ensure the safety of drinking water by risk assessment and systematic prevention approach. The purpose of this study was to assess the risk and identify hazards from the production source to the point of use and plan to reduce or eliminate these hazards to provide safe drinking water. This study was conducted on the water supply system of Talesh city in 2021. The WSP has 12 stages and the third stage is risk assessment and hazard identification. This stage scored 69 points out of a total of 100 raw points, which indicates 69% coordination with the WSP. Based on the analysis, 47 hazards were identified in production sources, transmission lines, distribution network, and point of use. The presence of domestic sewage wells near the source of supply, undesirable chlorine concentration, and old pipes in the distribution network, as well as the failure of the check valve at the point of consumption are the most important risks. With the implementation of different phases of WSP, especially the stage of identification and assessment of microbial contamination risk in the distribution network, has been decreased to 0% and the desired residual chlorine concentration has been increased to 100%. Currently, water supply system of Talesh has a moderate level of safety.