High-purity water systems require the Reverse Osmosis (RO) (RO) membrane process to generate semiconductor-grade purity water, a necessity for wafer production. For companies involved in wafer production, it is critical to therefore reduce the operating costs of RO and there have been numerous approaches implemented to do so. The design of an RO system that has a high recovery rate and hence a low-specific energy consumption is permitted through the use of low-energy RO elements high-purity water systems in fabs located in Taiwan. This article provides background of high-purity water systems, expands on RO systems and operation and demonstrates energy and chemical savings resulting from the replacement of aged RO elements.