<prompt> Minimum recommended level of Residual chlorine in Swimming pools is:0.5 mgL0.7 mgL1.0 mgL2.0 mgL  <response>: - Level of residual chlorine to be maintained for swimming pool sanitation is 1.0 mgL with contact period of 1 hour. - Also Remember, Free residual chlorine levels recommended in:- Drinking water 0.5 mg L ; with contact period of 1 hour. Drinking water to kill cyclops 2.0 mgL ; with contact period of 1 hour. 