It depends on the quality of the filtration. Not all RO water is created equal. Some comes from low budget RO systems and they filter out the majority of junk, whereas there are high end filtration machines that pass through multiple carbon layers, filtration levels, and other processes that can alter the quality of water. Unfortunately any answers you get will be of a rough idea and cant reflect your water quality to a T as it doesn't take into account the method of RO or the level of filtration it might have gone through. Sorry I cant be of more help.