The PX-220 Pressure Exchanger (PX) energy recovery device (ERD) was introduced to the SWRO market by Energy Recovery, Inc. (ERI) in 2003. Recipient of the Sidney Loeb award for innovation in 2006, the PX device has become standard equipment in SWRO applications, installed or specified in over 400 plants worldwide, with sufficient capacity to produce nearly 1.8 million m(3)/day of freshwater and to save customers an estimated 230 MW of energy or $162 million a year in operating costs. With one moving part, tough engineered-ceramic construction and exceptionally high efficiency, the PX device is designed for easy, long-term, maintenance-free, low-cost operation. Has the PX device lived up to expectations? The authors showcase a number of SWRO installations that utilize PX technology and quantify long-term performance and reliability.