what range of distances do you want to monitor and whats the level of accuracy or how granular can the readings be and remain useful? I would be happy with any reasonable accuracy less than 1m. Distances between 1-8m. Ideally the more accurate the better. Best case (read:accuracy), I would use this...

I am looking to build a device that monitors the level of liquid in an upright cylindrical container. Due to the nature of the liquid and the environment, IR is not preferred, as steam is likely and the rising steam may interfere with temperature based readings. This container is approximately 25 ft...