We read with interest the letter from Cuadrado-Payan and colleagues1 on the potential environmental benefits of newer hemodialysis systems (NxStage System One, Physidia S3, Tablo, and DIMI) compared with conventional machines. Because these devices are designed to operate at lower dialysate flows, we agree they can reduce dialysate use and associated water consumption. However, some systems—notably Physidia S3 and, in some configurations, NxStage—rely on packaged dialysate. Producing dialysate bags requires several liters of source water per liter of purified water, plus additional water for plastic manufacture.