Given the popularity of swimming for recreation and sport, it is remarkable that we are only in the early stages of understanding swimming pool chemistry, human exposure(s), and potential health risks. This is partly due to the complexity of swimming pool water chemistry, which increases with transformations that water undergoes as it moves from its source to pools filled with swimmers. Source waters are variable mixtures containing low levels of hundreds to thousands of chemicals originating from natural and anthropogenic inputs. Source water is then modified by disinfection processes at the water treatment plant. This chemically diverse and continually changing mixture reaches the swimming pool facility where it undergoes major changes due to additional disinfection and swimmer activity. Each pool has a unique set of characteristics that, combined with varying chemistry of source waters, makes characterization of chemistry, toxicity, and exposure an extraordinarily difficult undertaking.