The reverse osmosis (RO) membrane is subject to scaling from calcium carbonate in the feed water. To reduce the possibility of scaling while the system is in stand-by (ECO-mode), the system uses a backflushing feature. The system flushes feed water out from the RO module with pretreated water. As a result, the RO membrane is then standing in pretreated water instead of feed water, reducing contact with calcium carbonate. The backflushing process can also be started manually.