###### Abstract  
The need for water supply companies to exercise control over the operating conditions of water supply networks has contributed to the development of a number of methods for their diagnosis. The diagnostics of technical infrastructure is a constantly developing field, and therefore, over the years, we have observed the development of various methods of diagnosing network operating conditions and their classification. The article presents, in a synthetic way, the division and review of the previously used methods of diagnosing the operating conditions of water supply networks. The authors also classified and assessed the usefulness of the methods of diagnosis in specific operating conditions. The review carried out by the authors shows that there is a need for research on the detection of operating conditions of water supply networks under the operating conditions of real systems. The results of our deep analysis allow for the understanding of the most important areas of research, as well as the existing worldwide trends in the development of methods for leak diagnosis and detection in water distribution networks. This review is a compendium of knowledge on the detection and diagnosis of water supply networks. b 2022  
operational features of the system or its individual components. It should be noted that in technical systems, in a given moment, there are many operating conditions within individual devices and objects, and in the case of linear systems, such as water supply networks, they are also within different points of water supply systems. Water supply networks are subject to measurements of flow and pressure at various control points, water consumption by consumers and selected indications of water quality. Parameters of water supply network conditions are defined as a set or elements of a set of measurements of the water volume flow rate or pressure at the analyzed point. Most contemporary scientific studies place the greatest emphasis on diagnosing the operating conditions of a water supply network but mainly in the context of its failure rate and potential water leakage [6], while they are less related to the detection of abnormal conditions related to its operation. Such situations may also include the outbreak of the COVID-19 pandemic, as studies indicate a significant increase in residential water use following the introduction of government restrictions [7]. The random nature of water consumption, and the hydraulic parameters achieved as a result, presents a serious barrier to assessing whether or not the operating condition of a network can be considered relatively normal. In order to be able to speak unambiguously about the state of operation of the water supply network, this issue should be treated in a comprehensive manner. Due to parameters constantly changing in water supply systems (roughness coefficients of pipes, water levels in reservoirs, and water demand), the assessment of their operating conditions is a complicated and multi-criteria task. The need to solve the above-described problems concerning the assessment of the operating conditions of water supply infrastructure has contributed to the development of a number of diagnostic methods. For the first time, most of these methods were applied to gas and oil pipelines, mainly for safety reasons and awareness of the toxicity of the transmitted medium and the consequences that failures can bring. Although this aspect also applies to other linear infrastructure, it is in the case of water supply systems that the greatest number of deterministic and random factors can be observed that influence the complex character of phenomena occurring inside the pipes. This paper presents a synthetic overview and a breakdown of methods for the detection of water supply network operating conditions, for which a growing interest has been observed in the last two decades.