Predictive indicators of the safety of swimming pool waters

Many outbreaks related to swimming pools could have been prevented or reduced if the pool had been well managed and effectively monitored. The aim of this study was to evaluate physicochemical and microbial parameters that can be proposed as an indicator for the safety of swimming pools. A total of 234 water samples, over a 10-month period in 2006-2007, were collected from indoor swimming pools in Isfahan. All water samples were analyzed for physicochemical and microbial parameters including temperature, pH, turbidity, conductivity, free chlorine, heterotrophic plate count (HPC), total (TC) and fecal coliforms (FC), fecal streptococci (FS) Staphylococcus aureus (Sa) and Pseudomonas aeruginosa (Pa). The highest isolation of microbial indicators was for total coliforms (38%) and the lowest for fecal streptococci (3%). The correlation analyses indicated that free chlorine concentration had a significant negative relationship with the heterotrophic bacteria population and total coliforms. Total coliforms presented a significant correlation with the other microbiological indicators. The results clearly showed that the hygienic quality of the swimming pools was dependent on the efficacy of disinfection. Thus, the free chlorine and pH were good operational indices for the quality control of swimming pools and must be maintained in the recommended range to ensure optimal disinfection. The results also showed that TC and HPC were reliable and practical indicators for routine quality surveillance and assessment of the efficiency of the disinfection process and safety of swimming pools.