A beverage system includes a pump that draws a set amount of a flavored concentrate into a mixing chamber through a conduit for mixing with water to form a beverage. A sensor detects when the amount of the flavored concentrate in the conduit is low or the amount of the flavored concentrate in a concentrate container is low or out. The sensor includes two wings each including a recessed surface that together define a circular space. A portion of the conduit is received in the circular space. Each of the wings includes an ultrasonic portion that emits ultrasonic waves that are non-intrusive. When the amount of flavored concentrate in the conduit is low, air bubbles are generated in the flow of the flavored concentrate as it flows along the conduit and/or a vacuum is created in the conduit to draw the conduit away from the recessed surfaces. The ultrasonic waves detect either of these two features, indicating that the amount of the flavored concentrate is low.