The present disclosure relates to a fluid level sensing system for sensing a fluid level in a well. The system has an upper housing in communication with a lower housing, with the lower housing having a first bore in communication with a fluid in the well, and a second bore isolated from the first bore and in communication with at least one of a vacuum gauge or an external vacuum source. The upper and lower housings house a first flexible bag and a second flexible bag, with the first bag housed within the second bag. A portion of the first bag communicates with the first bore and is responsive to a change in pressure within the first bore caused by a changing fluid level in the well. A portion of the second bag communicates with the second bore and exerts a reference pressure on the first bag. A sensing subsystem senses expanding and contracting movement of the bags and generates a signal indicative of a change in a level of the fluid in the well.