This analysis presented in this paper assesses the difference in the performance measures due to the inclusion of an energy recovery system into a small reverse osmosis (RO) in terms of plant availability. The failure behavior of an RO plant including an energy recovery Pelton wheel turbine is analyzed along with its operational time. The plant is divided into main subsystems and the availability/unavailability of each subsystem is derived. the overall availability of the RO plant with and without the energy recovery turbine are derived from the performance of its subsystems and were compared. Assessment of the operational time of the plant was considered to be more appropriate than other performance measures since the plant was designed for continuous operation. The plant subjective assessment of failure probabilities of subsystems was made wherever detailed data were not available.