If you're set on using your MX display and the Dallas One-Wire sensor for this project, you could attempt to waterproof the sensor with an epoxy and place it in your reservoir. This is not a standard application of the device and I would highly recommend doing extensive testing before placing it in your computer. Matrix Orbital of course cannot be responsible for any damage resulting from the set up.
Or maybe with a DS2450 in combination with that probe but i'm guessing here, It'll take some custom hardware and possibly software to get it working for sure.