The whole issue it that it won't be falling from the sky in the manner we're used to. Plenty of places will dry up entirely, as California already is. Many places with an abundance of it will be flooding regularly. Agriculture will be tapping everything that it can. If you really are in a place that will remain stable and maintain consistent access to untainted water, we'll, how many people can your well serve? Because in that case you are where the refugees in your own country will be headed.

Furthermore, should things get that serious... The idea that you legally own the water that falls or otherwise gathers on your property, or that you will even remain the sole legal owner of such valuable land, is one that can be changed very easily by a thirsty population or desperate government. Not only that, wells represent the tapping of an areas water table. Any one can do that, and there are far more efficient ways to suck out the water table until it sinks out of reach. When water is that valuable and you have it, you'd better believe the water companies can and will drain you dry.

All of the norms that you rely on as the foundation of your way of life are subject to change, at the hands of nature and person alike. All of them.