The water used in swimming pools, like drinking water, must comply with the required quality. Failure to comply with the physical, chemical and biological criteria of the pools will lead to health hurt to swimmers. In this cross-sectional paper carried out with a descriptive-analytical approach in the summer of 2019, 23 public and private pools located in the south of Tehran (districts 18 and 19) were selected. Pool water sampling was performed to determine microbial indices including thermophilic coliforms, heterotrophic plate count (HPC), and physicochemical parameters including turbidity, pH and residual chlorine. Then, each of the studied parameters was assigned a weight based on their importance and their status was analyzed by water quality index. Based on the findings, the microbial indices of thermophilic coliforms and HPC in the water of the sampled pools were at the desired level in 74 and 26.1% of samples, respectively. Regarding turbidity, pH and residual chlorine content in 13.1, 60.9 and 47.9% of the samples, were at the acceptable values, respectively. The results also showed that none of the sampled water was in excellent condition and 68% of the samples were in fair condition in terms of water quality. According to the obtained results, the necessity of continuous sampling of pool water to check their quality and effective interventions and finally the imposition of fines is suggested for those which their quality is not in accordance with the standards
