Responded to service call in Lake View regarding a malfunctioning reverse osmosis system. Upon inspection, identified failure of automatic shut-off valve causing continuous drain flow and inefficient operation. System was an EcoWater ERO-375 installed approximately 4 years ago. Replaced shut-off valve assembly and performed comprehensive system check. Discovered TDS membrane was operating at reduced capacity (68% efficiency versus expected 95%). Replaced membrane and sanitized all components according to manufacturer specifications. Also noted sediment pre-filter was prematurely clogged due to recent municipal water main work in area. Installed higher capacity sediment filter to prevent recurrence. Calibrated pressure regulator to maintain optimal 65 PSI. Post-repair testing showed TDS reduction improved from 78% to 97%. Flow rate restored to 0.9 GPM at faucet. System now operating within all specifications. Provided customer with maintenance schedule to prevent future issues.