Abstract: An apparatus for optically monitoring a fluid level of a container comprises a light emitter(s), a plurality of optical detectors, and a control system. The light emitter(s) is configured to emit light toward a target surface when positioned, at a fluid threshold level, on the outside of the container. Upper and lower optical detectors are configured to receive light reflected from the target surface when positioned on the outside of the container above and below the fluid threshold level. The control system detects, based on measured reflectance received by the upper and lower optical detector, whether the upper optical detector is above the fluid level and whether at least a portion of the lower optical detector is above the fluid level, and determines, based on these detections, whether the level of fluid within the container has dropped below the fluid threshold level.