Influence of hydrotherapy pool water recirculation regime on Staphylococcus species concentration at subsurface: Preliminary experimental data from a pilot.

Pools are prone to contamination from microbial pathogens from human external microbiota, including mainly Staphylococcus species. These bacteria originate mainly from the skin and rhinopharynx and tend to concentrate at the surface/subsurface. Being protected by films derived from mucus and sebum, they are markedly resistant to biocides. Our study aimed to evaluate the respective impact of mixed and reverse hydraulicity techniques on the concentration of Staphylococcus species at the subsurface following bathing by four individuals in an experimental pool. Disinfection, filtration and water renewal of the pool were stopped in order to study only the influence of the water recirculation regime. We found a significant reduction of 31.7% (Test 1), 50.9% (Test 2) and 41.9% (Test 3) in total Staphylococcus species counts at the subsurface when using reverse versus mixed hydraulicity. However, this reduction is not a pollution cut but a pollution shift, resulting from an increase in the outlet water flow rate by overflow channel from 49.3 to 100%. This experimental model was far removed from real life conditions and associated with a series of limitations. However, it seems that the type of water recirculation regime is a critical factor in the bacterial quality of pool water. These preliminary findings need to be confirmed in additional studies using more realistic conditions.

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