This is just one of those things, like who cooks your food at resturaunts ( and how clean are they) that I just don't think about if I did I would never swim at a public pool. I know at water parks they have to check the PH levels ever so often and if they are too high they have to close the area until treated. I think I have seen the lifeguards at Disney doing this also. It is beyond gross though if you think off all the hundreds of bodies you are swimming with (that is why I just don't go there)