Increasing temperatures globally affect precipitation patterns, frequencies, and quality, and as a result, decrease in water resources and drought occur. This situation has become palpable in Turkey between October 2022 and March 2023, and some dams across the country have dried up and the water level of some dams has dropped to a very low level. These emerging problems have made it a necessity to use water more efficiently. Rainfall is extremely important in feeding water resources. However, the increasing urbanization and the increase in impermeable surfaces affect the feeding of water resources negatively. Water collected from surfaces such as roofs, avenues, streets, squares or gathering areas cannot be evaluated at first hand by giving them to rainwater or sewer lines. Precipitation water must be collected and stored to be evaluated in situ. Here, it is important to analyze the cost to be made for storage and to determine how long it will take to recover the expenditure to be made. From this point of view, in the study carried out in Kayseri University 15 July Campus, the on-site evaluation of precipitation waters and the cost analysis of this process are discussed. Within the scope of the study, firstly, the settlement plan of the 15 July Campus of Kayseri University and the roof plans of the buildings on the campus were provided. In the second part, the surfaces where precipitation water can be collected are determined, the materials used in these areas and the status of the materials are determined and the amount of precipitation water that can be collected is calculated. In the third part, depending on the amount of precipitation water that can be collected, the storage volume, type and location are determined, and the cost is calculated. In the last section, the efficiency of the rainwater collection system is evaluated. As a result, a general evaluation on the subject was made and solution suggestions were presented. It is hoped that the study will contribute to the literature and other studies to be carried out.