Water Rights are considered personal property and can be sold from 5,000 to 10,000 dollars a foot lately. The history goes back a long way and is explained
here.
There are many factors to consider. The fact that someone is selling 6 acre feet in Iron County to an out of stater sends up a red flag to me. Depending on where they are, they can be highly sought after. You can sell them and they can be transferred, but there are restrictions you need to know.
Having a Water Right is just that, you have the right to take that much water from the ground, if you do not use it, it can be taken from the state, many "lease" them to local farmers. There is no guaranty of water being under your land.
If it is in the Beryl/Enterprise area, that is a whole nother post!
I have seen many people buy land here and then come out and be thwarted by the process in building. It is doable, just do your research. Wells, septic, power etc. require a lengthy and paper filled process.
I am glad to see you are researching it!