Eventually the day comes when your RO system will require cleaning. Cleaning is
recommended when your RO shows evidence of fouling, just prior to a long term
shutdown, or as a matter of scheduled routine maintenance. Fouling characteristics
that signal you need to clean are a 10-15% decrease in normalized permeate flow, a
10-15% decrease in normalized permeate quality, or a 10-15% increase in
normalized pressure drop as measured between the feed and concentrate headers.