Chlorine neutralizes contaminants from humans (such as sweat and sunscreen) and organic debris  (such as bugs and leaves) so that you do not get sick from the pool. Without chlorine, the pool water  eventually would turn green and become unsafe to swim in. A swimming pool is required to have a minimum of 1.0 ppm (parts per million) and no more than 5.0 ppm of chlorine. We check chlorine  regularly. On average, pool chlorine is at 3 ppm.