Comparison of pool water quality before and during the COVID-19 pandemic – a case st

Abstract

The quality of pool water was compared before and during the COVID-19 pandemic in a selected swimming pool. The principles of operation of this swimming pool during the pandemic and their impact on the quality of swimming pool water were presented. The collected operational data of the water treatent system and the analysis of the results of tests of water samples taken from the pool basin and from the circulation system in two 
time periods (before 02.09.2019-19.03.2020 and during 26.03.2020-25.02.2021 the  (pandemic) allowed to determine better water quality during the pandemic. In the swimming pool water, lower concentrations of combined chlorine were measured (0.25 on average compared to 0.28 mg Cl2/dm3 before the pandemic), lower values of oxidisability (1.0  on average compared to 1.7 mg O2/dm3 before the pandemic), lower nitrate concentrations (7.8 on average compared to 10.4 mg NO3–/dm3 before the pandemic) and lower concentrations of chloroform (0.012 on average compared to 0.019 mg/dm3 before the pandemic). The bacteriological improvement in water quality was apparently noticeable. Before the pandemic, a high degree of bacteriological contamination of swimming pool and circulation water was determined 3 times (total number of mesophilic microorganisms, TNM > 300 CFU/1 mL). Such a situation was not found during the pandemic. The improvement 
of the water quality was significantly influenced by the reduced number of swimmers (from a maximum of 40 to a maximum of 20 per hour) and shorter operation time of the filters (from 7 to 4 days between washing of the filter bed). The presented comparison may provide a new source of information on the operation of swimming pools during a pandemic or in a time of a pandemic threat.