The research established that 1.5mg per litre of free chlorine with a pH between 7-7.2 reduced the infectivity of the virus by more than 1000-fold within 30 seconds.
Additional testing of different free chlorine and pH ranges confirmed that chlorine in swimming pool water was more effective with a lower pH which is in line with current guidance for swimming pool operation.
Professor Wendy Barclay, Imperial College, said: “We performed these experiments at our high containment laboratories in London.
“Under these safe conditions, we are able to measure the ability of the virus to infect cells, which is the first step in its transmission.
“By mixing the virus with swimming pool water that was delivered to us by the Water Babies team, we could show that the virus does not survive in swimming pool water: it was no longer infectious.
“That, coupled with the huge dilution factor of virus that might find its way into a swimming pool from an infected person, suggests the chance of contracting Covid-19 from swimming pool water is negligible.”