I just bought my collection of CI and nowhere does it say to not use water, as a matter of fact water is recommended to remove the crud.
My dad's CI is 50 years old and he uses water after every use. Crud is not seasoning. I know from using stones that leaving the crud on can be very damaging to the equipment. Go ahead and use very hot water on you CI and then add some vegetable oil to the pan after it's dry.
I put the gunky pan filled with a few inches of water onto the stove and set to a boil. Then I dump out the water and pour Kosher salt into the hot pan and use a paper towel to scrape the gunk off. A wipe with an oily paper towel and you are good to go.