This says the humidity of the Sahara desert is 25%. I wonder if you could devise some kind of system to collect water from the air? (Taking advantage of the big difference in day and night temperatures)
The Appendix of Dune is what solidified it as one of the best books I've ever read. I remember him going in to detail about how the planet had a type of desert flower that would grow at the bottom of dunes that acted as a catch for the morning dew, concentrating it and preventing it from evaporating away and thereby making pockets of water for the local animals.
https://saharadesertinfo.weebly.com/humidity.html