Water utilities in arid regions deal with multifaceted issues of natural groundwater contamination, high treatment costs, and low water rates. These utilities rely on intermittent supplies resulting in numerous water quality failures at source, treatment, distribution, and in-house plumbing systems. The present research presents an inclusive risk assessment methodology for managing water quality from source to tap. Three-year monitoring data for turbidity, TDS, pH, iron, ammonia, nitrates, residual chlorine, Coliform group, E. coli, and Fecal Streptococci identified the root causes of failures. The cause-effect relationships in the form of a fault tree were solved using multiple failure modes and effect analysis (FMEA) to handle both the Boolean operations. The fuzzy sets addressed the uncertainties associated with data limitations in calculating exceedance probabilities (Pe) and vagueness in expert opinion for subjective evaluation of severity and detectability. The methodology was applied on a smaller system serving 18,000 consumers in Qassim, Saudi Arabia. Potable supplied water underwent reoccurrence of TDS (Pe = 20%), turbidity (Pe = 10%), and Fe (Pe = 2%) failures in distribution that further increased up to 44%, 33%, and 11% at the consumer end. The Pe for residual chlorine failure soared up to 89%. Economic controls reduced the cumulative risk to 50%, while the shift to continuous supply can limit the remaining failures under the acceptable risk. The framework will help utilities manage water quality in intermittent systems from source to tap in Saudi Arabia, the Gulf, and elsewhere.

中文翻译：

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干旱地区间歇供水系统的自来水风险评估来源：综合 FTA——模糊 FMEA 方法

干旱地区的供水公司处理自然地下水污染、高处理成本和低水费等多方面问题。这些公用事业公司依赖间歇性供水，导致源头、处理、分配和内部管道系统出现许多水质故障。本研究提出了一种包容性风险评估方法，用于管理从源头到自来水的水质。浊度、TDS、pH、铁、氨、硝酸盐、余氯、大肠菌群、大肠杆菌和粪便链球菌的三年监测数据确定了失败的根本原因。使用多种故障模式和影响分析 (FMEA) 来处理两种布尔运算，从而解决了故障树形式的因果关系。模糊集解决了与计算超出概率 (Pe) 时的数据限制相关的不确定性以及严重性和可检测性主观评估专家意见的模糊性。该方法应用于为沙特阿拉伯卡西姆的 18,000 名消费者提供服务的较小系统。饮用水在分配中再次发生 TDS (Pe = 20%)、浊度 (Pe = 10%) 和 Fe (Pe = 2%) 故障，在消费者处进一步增加至 44%、33% 和 11%结尾。余氯失效的Pe飙升至89%。经济控制将累积风险降低到 50%，而转向持续供应可以将剩余的故障限制在可接受的风险之下。该框架将帮助公用事业公司管理沙特阿拉伯、海湾和其他地方从源头到水龙头的间歇系统中的水质。