The R.O. flush kit is strongly recommended for units that are used to purify hard water or water that contains heavy amounts of iron, calcium, and/or magnesium. These elements can clog a membrane in a short amount of time. By using the flush kit once a week for just 15 seconds, you can actually extend the life of the membrane by forcing water over the membrane, which dislodges damaging build-up. This simple process can lengthen the life of your R.O. membrane by as much as six months!