ASFs habitat crosses into desert scrublands and the southern portion of the Saharan desert.
And deserts doesn't always specifically mean sand dunes....
Yes, they also have other habitats as well, but urinating not as often is a biological adaptation to the desert. (think Hamsters as another example).
(referenced from Anita M. Oberbauer, B.S. Zoology, Ph.D. Animal Physiology.)