The disclosed technology includes a non-powered valve assembly having a valve, an actuating system, and a trigger. The trigger can be in mechanical communication with the actuating system and the actuating system can be in mechanical communication with the valve. The trigger can be positioned such that the trigger can interact with liquid resulting from a leak in a plumbing assembly. Upon interaction with liquid, the trigger can dissolve or expand, causing the actuating system to be activated and the valve to transition from the open position to a closed position. In the closed position, the valve can restrict the passage of liquid through the plumbing assembly such that the leak can be mitigated.