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. 2021 Oct 15:205:117718.
doi: 10.1016/j.watres.2021.117718. Epub 2021 Sep 30.

Inactivation of SARS-CoV-2 in chlorinated swimming pool water

Jonathan C Brown  1 , Maya Moshe  2 , Alex Blackwell  3 , Wendy S Barclay  2
Affiliations

Inactivation of SARS-CoV-2 in chlorinated swimming pool water

Jonathan C Brown et al. Water Res. .

Abstract

SARS-CoV-2 transmission remains a global problem which exerts a significant direct cost to public health. Additionally, other aspects of physical and mental health can be affected by limited access to social and exercise venues as a result of lockdowns in the community or personal reluctance due to safety concerns. Swimming pools reopened in the UK on April 12th 2021, but the effect of swimming pool water on inactivation of SARS-CoV-2 has not yet been directly demonstrated. Here we demonstrate that chlorinated water which adheres to UK swimming pool guidelines is sufficient to reduce SARS-CoV-2 infectious titre by at least 3 orders of magnitude.

Keywords: Chlorine; Coronavirus; Inactivation; SARS-CoV-2; Swimming pools; Water.

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Conflict of interest statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Alex Blackwell (AB) works for Water Babies as their Group Head of Facilities and Operational Management. Water Babies is a swim school franchise network that hires pools to provide swimming lessons. Water Babies does not manufacture or sell swimming pool(s), equipment or disinfection products. AB sourced funding for this project from Swim England, Royal Life Saving Society UK (RLSS UK) and the Spatex Foundation. AB acts as the Lifeguard advisor for the RLSS UK and is also a member of the Pool Water Treatment Advisory Group - Industry Forum.

Figures

Image, graphical abstract
Graphical abstract
Fig 1
Fig. 1
Exposure to chlorinated water inactivates SARS-CoV-2. Water samples taken from a swimming pool were modified in the laboratory to a range of pH and free chlorine values. A known amount of infectious SARS-CoV-2 was added to duplicate water samples in a volume of 1 ml, incubated for 30 s at room temperature and any remaining infectious virus then titrated by TCID50 on Vero cells. Residual virus titres are shown as the mean and standard deviation of duplicate TCID50 ml−1 values. Successive experiments were performed with varying free chlorine levels (a), varying pH (b), a range of both pH and free chlorine levels (c), and an independent preparation of virus at a range of pH and chlorine levels (d). A PBS control was included in each experiment to validate the infectivity of the virus input. Lower pH and higher free chlorine levels resulted in greater inactivation of SARS-CoV-2. A pH of no more than 7.4 and free chlorine above 1.5 parts per million (ppm) resulted in at least a 3-log10 reduction in viral titre. Dotted line indicates the lower limit of detection of the assay.
See this image and copyright information in PMC

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