-
Allegedly not at all. It's thought SARS-CoV-2 is inactivated by normal swimming pool chlorine etc. The infection risk is probably in the changing room, door handles etc.
And talking to people at the ends of lanes. I think that's the biggest problem as there are generally a bunch of people that sit at the end of the lanes in between sets. Not everyone does one big long set with no rests.
How long does the virus survive in swimming pool water?