Water filter repair. 1/4” poly pipe quick connect coupling was leaking on the discharge line of the RO system when I arrived. New coupling installed and the leak was fixed, but there is a problem with the RO system. It is constantly running full pressure through the discharge line and not the filling system. Problem with filter membrane or discharge valve, or check/ fill valve, I’m assuming. The system is 10+ years old, and I recommend that the customer order a membrane filter and replace it as a start, because that was one of the troubleshooting options if this happens. If a problem occurs after I recommend the installation of the new system