How far do you walk or run everyday?I use 4 stage Filtration, for my grow room and 6 stage for drinking / cooking water. I run my drinking water through a Carbon taste and odor filter and a PH filter to add back some minerals. The first four stages are sediment filter, carbon block filter, Chloramine filter and RO membrane. I change all filters except the RO membrane every year. I'll replace the RO membrane when TDS rejection rate goes down below 85%. I'll usually get at least 4 years from a RO membrane with the chloramine filter and maybe a year without one. Local water supplier denies the use of chloramines and I have not had water tested by a lab. I am a plumbing contractor and I do service on residential RO systems and this is consistent in my area.