Firefly seems to make an economic assessment on the value of water along the lines of the econ 101 thought-experiment of the water-diamond paradox. (Said thought-experiment simply noting the primacy of scarcity over function in valuing a good on the free market.) In Firefly's future, it would appear that water is an expensive commodity, at least when bought for terraforming. The poorer the planet, the drier the climate and Heart of Gold is no exception. Unlike the wild-west styled dust-balls of Our Mrs. Reynolds and Safe, or the muddy mess of Jaynestown, Heart of Gold takes place almost entirely in a desert.