The water quality standard of swimming pool requires much higher residual chlorine content than tap water. Why?

According to China's Hygienic Standard for Swimming Places (GB9667- 1996), the content of free residual chlorine in swimming pool water is 0.3-0.5 mg/L.

According to GB 5749-2006 Hygienic Standard for Drinking Water, the residual chlorine in user's water is ≥ 0.05 mg/L; The residual chlorine content in the factory water is ≥0.3mg/L, and the water supply company generally controls it between 0.3 and 0.5 mg/L..

Through the above comparison, the residual chlorine standard of tap water is far lower than that of swimming pool water, because tap water is directly related to people's daily diet, and the residual chlorine is of course very small. Swimming pool water is generally in contact with the swimmer's external skin, so the residual chlorine value standard will be higher.