For your 13 Stage Beyond O2 Water to continue to work at its optimum,

It's extremely important: Every 3 years, replace the 6^th filter which is an additional $150

This superior filter removes the tiniest of contaminates...micro plastics, pharmaceuticals, lead, arsenic, fluoride, nitrate/nitrite, bacteria, fentanyl, cysts (such as Cryptosporidium and Giardia), chlorine, heavy metals, and so much more!