Here's the storm total. The scale tops out at 25 inches, but there are reports of more than 50. Essentially all of Harris County had more than 25 inches. Galveston, Chambers, Liberty, Hardin, Jefferson, and Orange Counties are entirely covered in white. More than half of Jasper County and just about all of Tyler County are, too. Beyond this, all the way up to Bryan and Lufkin there are 18 inch totals, which in most storms would be extreme.
Interestingly, out over the Gulf, where it wouldn't hurt anyone, the totals are much less. I know a little about meteorology, and I can't think of any reason why the heaviest rain would be over land. The outer bands often produce tornadoes over land because of the lower-level winds being impeded, which reduces the Coriolis effect and changes the direction, which introduces shear and can produce horizontal vortex tubes that can be verticalized and stretched by convective currents to form tornadoes. I've never paid to see if tropical storms usually drop more rain over land. This one does seem to have stayed stronger over Texas than a landfallen storm usually does because it was feeding off its own rainfall, what Wikipedia calls the "brown ocean effect." I remember John Hope long ago talking about Danny getting stronger over land as it approached the ocean, and surmising that it was due to this effect.
