Swimming is a very honest sport. This sport uses almost all major muscle groups and places a vigorous demand on your heart and lungs, it's better than any training machines that usually use only one group of muscle. Pool water becomes more balanced due to lowered chemical use. Seldom requires brushing. Less vacuuming due to constant coagulant effect. Less backwashing. The pool remains free from bacteria, viruses and algae. The use of chlorine is reduced, and so are its harmful by-products (chloramines, chlorinated hydrocarbons). The use of pool chemicals that are harmful to the environment are reduced (chlorine, acids, alkalis) or made redundant (algaecides, flocculent/ coagulant).