How old can babies start to go into public swimming pool?

Personally I will only bring after her neck is stable so about 4 months too. I let my gal wear a Konfidence wetsuit and Charlie banana swimming diapers. And when they are still so young I read before keep it to no more than 20mins for every swimming session. I usually bring my baby only to the swimming pool of hotels or condos and not really the public Kind as I am concerned it may have a lot of bacteria. I also have a inflatable swimava pool that I use at home when she was only 4mths old so she can float in warm water at home.