I live in North San Diego County and we desalinate ocean water. It costs less in electricity to desalinate right here than to transport it from the Sacrament delta! Not too many people know that, but water transportation uses about 25% of the electricity generated in California. Shipping it from Florida would cost more than desalinating the Pacific Ocean, the Gulf of California, or the Gulf of Mexico. Same for all those "ship it from Oregon, Washington, or British Columbia" ideas.
That's why the idea that we will have "fresh water wars" is BS: Fresh water is available almost everywhere, it just has a cost that's higher than a river running through town. But the cost is surprisingly low, and you can even generate the needed electricity with solar panels since it doesn't have to run at night.