The success or failure of a project in achieving predefined objectives is largely dependent on the suitability of its execution system. An important decision in the early stages of a project is to investigate different possible ways for executing projects and selecting the best one. This requires the identification of risk taking of projects. Risk is, in fact, the same as uncertainty and a multidimensional concept affecting the project's objectives. Risk management is defined as the risk identification and assessment process and application of specific methods to reduce risks to an acceptable level. Therefore, the initial objective of project risk management is risk identification, evaluation and control for the success of projects. The risk management standard published by the Project Management Institute (PMI), entitled Project Management Body of Knowledge (PMBOK) was used in this study as the basic method for describing risk management. The general objective of this study was to develop a risk management model for water and sewage projects using Interpretive Structural Modeling (ISM). The statistical population included all experts involved in the field of water and sewage projects. The Delphi method was used for risk identification. Eventually, data was analyzed with the help of the ISM and driving power-dependence power diagram (MICMAC). According to the results, allocation of Islamic Treasury documents and bills, imprecise conduction of preliminary studies, the lack of coordination between project designers, irrelevant maps and details, imprecise initial project estimation, the lack of adequate maps and details and project failure and its conversion into some small projects with a high level of impact-dependence are highly prioritized risks needed to be controlled.