*1.1. Background and Problem Statement*

Water distribution networks (WDNs) in modern cities are usually large-scale, with complex systems and limited instrumentation. Water may be lost due to system aging, poor maintenance, and improper operations. The effective management of a water supply may be a serious engineering problem faced by cities, and rapid urbanization and infrastructure aging are expected to intensify in the future [1]. Faults in the pipeline system may not only cause problems in water resource management, but may also induce economic problems such as lost revenue or extensive repair times [2]. The faults in a pipeline or a WDN may be divided into three types: Leak, blockage, and deterioration, which may induce various problems. Leaks in pipelines and WDNs may cause large economic losses. Water supply networks leak an average of 20% of their water supply and lose an estimated U.S. \$9.6 billion each year [3]. This may also affect environmental health and safety [4–6] and create water quality problems, such as equipment failure, problematic operations management, and errors in pipeline design [4,7–9]. If a pipeline has blockages, this will reduce the pipe carrying capacity of the system and there will be severe safety problems [10]. Pipeline deterioration may not impose imminent threats

to the operation of pipeline systems, but it may reduce water transmission efficiency [11] and create water quality problems [12]. Hence, fault detection in WDNs is an important task in the community of water supply engineers.
