The project is based on the principles and needs defined in the “Strategy for the Development and Management of Water Supply and Sanitation in the Republic of Bulgaria in the period 2014-2023” and its Action Plan, the priorities for implementing investments in the water sector of the European Commission, as well as in the context of the ongoing reform in the water sector. The implementation of a regional approach is consistent with good international and European practices in the field of planning, implementation and management of WSS infrastructure and investment process. Realising the investment needs identified in the Strategy is a huge challenge and makes it imperative to plan them adequately, following a regional and integrated approach, respecting the principle of effectiveness and sustainability of spending and in accordance with the relevant strategic documents and regulations. On the other hand, the requirement for reimbursement of the costs of the investments made in WSS infrastructure and the recognition of adequate depreciation charges as a pricing element in the determination of the prices WSS services are the main objective in the implementation of future infrastructure projects. In this regard, the project proposal includes activities for the preparation of regional pre-investment studies (RPIPs) and application forms for European funding under OPE 2014-2020 for the designated territories of 14 WSS operators (WSSO), quality assurance services and control of their implementation, services for the assessment of public WSS assets for 29 WSSOs.