if it's for potable water the lines have to be cleaned and the holding reservoir has to be cleaned periodically or you can get sick and die from drinking contaminted ro water. but a reef tank won't die from contams in the lines or holding tanks, that's why only changing canisters works for reefing alone. the whole system is competing bioslicks with various pathogen inclusions, so some low-level unclean bioslicks from an RO system is the least of a reef tank's concerns.
anyone who is drinking water or giving it to their family from an RO unit that has never had the lines cleaned or exchanged as well as bioslicks removed from the holding tank is risking poisoning people, though you may get lucky for years.
where goes water goes bacteria that get their own feed and set up their own housing as slicks inside any habitable water system. pathogens can easily take up residence as well there. most reef aquarists do not espouse this fact because they've been trained by bottle bac salesmen and forum peers that bacteria can't form in water and remain there unless we're giving them 2 ppm of ammonia to eat everyday.
