<prompt> The recommended concentration of free chlorine is0.2mgdl0.5mgdl5mgdl10mgdl  <response>: The chlorine demand of water is the difference between the amount of chlorine added to the water and the amount of residual chlorine remaining at the end of a specific period of contact usually 60 minThe point at which chlorine demand of water is met is called the ;breakpoint chlorine;Chlorine added beyond breakpoint chlorine is free chlorine HOCl and OCl. The minimum recommended concentration of free chlorine is 0.5 mgL for one hour.The free chlorine provides a margin of safety against subsequent microbial contamination such as may occur during storage and distribution.Park 23e pg: 715 