I live in Florida, not really a desert but its hot.
Its easy to use 3 gal per day. Drinking, cooking, and basic washing. So I disagree.
We take two 5-gal jerry cans to the cabin, for five people, for a four-day weekend, and rarely run out.
Of course, we are suplimenting with other beverages...
There are two springs on the propeerty, but I would boil the water before drinking it.