To be more specific, the regular use to which swimming pools are put requires that they be cleaned on a regular basis. Exposed as they are, and frequented by a lot of people, swimming pools are places that are especially prone to infection if neglected. This paper, then, is intended as an explanation of the various measures taken by operators of swimming pools as to how to keep their waters safe, as well as how the public can do their part. The Importance of Swimming Pool Sanitation As detailed in a report by the World Health Organization (2006), swimming pools are vulnerable to pollutants such as bird droppings or even the rain. And while indoor pools are much safer, even they need to be cleaned at least once in a while just to be absolutely sure. Either way, as noted by the Centers for Disease Control and Prevention (2009), pathological contaminants often abound in swimming pools, which can cause a myriad of conditions such as diarrhea. A pool that is cleaned regularly is in effect guaranteed to be safe for the public to enjoy – guaranteed safe for them to swim in. … In the words of the Division for Environmental Health (2011), the only way to maintain safe and consistent swimming pool operation is through proper water chemistry. The exact process involved is often rather varied, not only in the chemicals that may be used but also in the methods employed. For one thing, disinfectants may be used to rid the water of harmful, objectionable or otherwise unwanted microorganisms. Alkalinity and pH adjusters may also be used to ensure that the pool’s pH and acidity levels remain stable, while algaecide and filter aids respectively kill any algae and prevent foreign material from spreading in the water. Swim King’s (2011) official website also tells us that the balance between these chemicals needs to be just right so as to keep the water free of any unwanted ‘lurkers’, yet still be safe for those of us who feel like taking a swim. For instance, free chlorine residual refers to the amount of chlorine which has yet to react with any other substance in the water besides the water itself, and should ideally be anywhere between 1-3 ppm. Secondly, combined chlorine refers to chlorine that fits the opposite description – that is to say, it has already reacted with a foreign substance. This kind of chlorine is no longer a help to the disinfection process, and indeed, only acts as an irritant. And finally, total chlorine residual is the sum of these two variants of chlorine. Besides chlorine, bromine can also be used to fulfill the function of disinfection. In fact, whereas the former is more prevalent in swimming pools (Sweazy, 2001), it is the latter that is the preferred substance among owners of spas and hot tubs (Wilson, 2002).