Product reservoir including intelligent level sensor

A method of operating a liquid level monitoring device, the method including operations comprising:

• controlling a transceiver that is mounted to a structure attached to a container to transmit an output signal into the container and receive a portion of the output signal reflected back to the transceiver as a reflected signal;
• determining a first level of a product in a container at a first time by comparing a characteristic of a reflected signal to a characteristic of the output signal;
• determining a second level of the product in the container at a second time that is a period of time after the first time;
• determining an expected level of the product in the container based on the first level of the product and a number and duration of dispense cycles that occurred between the first time and the second time;
• and
• setting an unexpected product level alarm condition if the second level of the product is greater than or less than the expected level of the product by more than a threshold amount.