You cannot catch HIV from being in a properly treated swimming pool.
Maybe the running water has some magical significance, like in the Fairy stories of Baba Yaga. Or in the Jewish Law, where if your house had dry rot or rising damp, you took two sparrows to a stream with a bowl. Cut the throat of one bird over the running water, catch the blood in the bowl. Dip second bird in blood, then release. Finally smash the bowl.
WHO SAID THE Borg gives you the equivalent of a COLLEGE education?
HB