Quantity and quality assessment of rainwater extracted from the roof for drinking water

Roof rainwater harvesting is considered an important alternative source where contaminated surface and groundwater resources are limited or not readily available. The aim of this study was to evaluate the quantity and quality of water extracted from rainwater harvesting systems for drinking water production at Sari Agricultural Sciences and Natural Resources University. To investigate the potential for rainwater harvesting within the university, one of the student dormitory buildings with a roof area of 850 m2 and a capacity of 300 students was considered. Daily rainfall data of Dasht-e Naz station in Sari in the period 2000 to 2018 were used as inputs of the water balance model to determine the appropriate volume of the rainwater storage tank. Also, in order to evaluate the quality of water collected from the roof, sampling from the roof outlet and some important physical, chemical and microbial parameters were measured. According to the results, the volume of the storage tank of 30 m3 in the dormitory with Volumetric and time reliability of 29 and 29.5 percent, respectively, was considered appropriate. The results showed that at the implementation of this system, about 309 m3 of town water consumption will be saved annually. The results also show that the direct use of collected water for drinking purposes is limited. Accordingly, according to the amount of water produced annually, it is recommended to use a UV system for disinfection and microbial purification while using a sand tank to improve physical parameters (turbidity).