Most of the time it does not matter. In actual fact they have to build in a bit of "slack" since the amount of chlorine or chloramine at any given point along the line will vary. As the distance from treatment plant to tap is so different and chlorine is used up as it encounters organics, the amount in your water will vary. The dechlor product will take care of a wide range. I think I have read on Prime that it is safe up to ten times the recommended???