From Aqua-safe (cut fr
here):
Life expectance is a result of TLC. If you flush the membrane every couple of weeks for 10-15 minutes (i.e. turn the knob) and change out the pre-filters every 600 gallons of product water, the membrane will last 5 years +/-. If chlorine or other killer chemicals get to the membrane, or if you have really turbid water (more than 1 NTU), then the membranes will fail sooner...as early as a year with high use and no TLC.