Just for the other side of things. How long did it take or how much water did you put in the tank the first time? Lets say you did fill it, when you tryed to get water from the faucet etc. did you hear the water pump run? If not then you need to check the fuse or connection to the pump. There may also be more than one switch for the pump and its broken.
Even if your inlet water line was blocked you would be able to add water, it would be a slow process however. Another way to check is open the fresh water drain valve to let the water out. That way you would know you are starting with zero water.
3500 Ram 5.9l diesel
08 35 RLT Cardinal
5th Airborne Pin Box