The RO membrane is a higher grade than the typical RO membranes and is graded to last 2 year, unlike other RO membranes that you have to replace every 3-6 months. It is a multi-stage system with the multiple stages comprised over the 3 cartridges. It uses typical and standard size filtration cartridge’s so sourcing replacements should not be an issue. We have additional cartridges if you would like to purchases additional supplies.