Systems, methods, and computer program products for monitoring a level of product (14) in a reservoir (10, 130, 140, 190, 260) of a chemical dispensing system. A lid (22, 148, 216, 302, 358) configured to engage an opening (28, 136, 138, 146, 204, 352) of a container (12, 198, 354) includes a level sensor (26, 244, 272, 342, 386) having a transceiver (36) that transmits an output signal (38) and receives a portion of the output signal (38) reflected back (42) to the transceiver (36). The level sensor (26, 244, 272, 342, 386) determines an amount of the product (14) in the container (12, 198, 354) by comparing a characteristic of the reflected signal (42), such as time the reflected signal (42) was received, to the characteristic of the output signal (38), such as the time the output signal (38) was transmitted. The level sensor (26, 244, 272, 342, 386) may also determine the size of the container (12, 198, 354) based on the reflected signal (42), and take this size into account when determining the amount of product (14) in the container (12, 198, 354). The level sensor (26, 244, 272, 342, 386) transmits product level data to a mobile device (54) in response to receiving an interrogation signal (66) therefrom.