Chlorine, even in small quantities such as is found in municipal water systems, will damage RO membranes.  If Carbon filtration is unavailable, sulfites can be used.  Like oxygen scavengers, sulfites scavenge the free chlorine before it makes it to the filters. 

Now that all the chlorine is gone from the water, bacteria may thrive.  If biofilm buildup occurs in your RO system, then additional biocides may need to be added.