Researchers at Imperial College London have demonstrated that chlorine in properly maintained swimming pool water can inactivate the SARS-CoV-2 virus—responsible for COVID-19—in as little as 30 seconds. This evidence supports the safety of chlorinated pools against virus transmission.
Back in May 2020, studies from France's Ifremer institute confirmed the coronavirus was absent from seawater and shellfish. Spain's CSIC also deemed chlorinated pool water safe, citing chlorine's ability to reduce COVID-19 virality. Imperial College London's recent research aligns with these findings, showing the virus loses infectivity in just 30 seconds.
“By mixing the virus with pool water provided by the Water Babies team, we showed it does not survive in chlorinated pool water and is no longer contagious. Combined with the massive dilution factor from any infected source, the risk of catching COVID-19 from pool water is negligible,” said Wendy Barclay, the study's lead author, in an April 16, 2021 statement.
The experiments used a free chlorine concentration of 1.5 mg per litre and a pH between 7 and 7.2, reducing the virus's infectivity by more than 1,000 times within 30 seconds. However, caution is advised: the study hasn't been peer-reviewed or published in a journal yet.
Additional tests indicate chlorine works even better at lower pH levels, offering reassurance for pool professionals and swimmers. While promising, it doesn't guarantee safe reopenings this summer without further validation.
