A fluid reservoir sensing system includes a pair of optical prisms or sensor targets that reflect light when a fluid level is below one of the pair of prisms or sensor targets. The pair of optical prisms or sensor targets includes a low prism or sensor target usable to sense a low liquid level in the fluid reservoir, and a high prism or sensor target usable to sense a high liquid level in the fluid reservoir, and a wicking means to wick fluid away from the high incident and low incident surfaces of the prisms or sensor targets that are above the fluid level. The fluid reservoir sensing system optionally includes an emitter and a photosensor.