I personally avoid chlorinated swimming pools even on vacation. I think I read in Kevin Trudeau 's (What they don't want you to know or something like this) that chlorine from water even when you shower is being absorbed by the skin and goes into the system. It is almost as if you drink concentrated chlorinated water. So, I don't think it's a good idea to swim in a chlorinated water during a fast. I have also heard about "swimmer's asthma" which is linked to chlorine. I wanted to sign up my son for swimming lessons and that was the reason I didn't. Anyway keep researching. They have some swimming pools disinfected with ozone I think. I am not sure. Otherwise I love swimming in the sea or ocean, and it is really good for the back. Good luck. Julia