This overview describes the several systems that comprise the Water Walls approach to creating a Life Support system using a simple membrane technology to replace the complex and too failure-prone existing life support systems. The primary innovation is to try to achieve reliability through the massive redundancy of inexpensive, passive forward osmosis membrane placed within simple but sturdy polyethylene bags. This overview starts with a chronology of the initial Functional Flow concept and how it was revised and simplified. Then it explains the Process Block approach and how it was ultimately consolidated to achieve more clarity and simplicity at the higher system level while developing refinement and component characterizations at the lower, subsystem level. This work was supported particularly by NASA contract NNA13AA38C funded by the NASA Innovative and Advanced Concepts program, and by the Ames Center Director’s Innovation Fund.