I've had three ducks for 6 years now. They are a hybrid mallard/khaki campbell cross. They are egg layers primo! Each girl in her prime laid an average (and I am NOT exaggerating) over 300 eggs per year! They are getting older now but still lay approx 3 eggs per week each!
Anyway, (didn't mean to get off track) housing can be simple or complex. I tend to go complex
. The main thing necessary is protection from predators since they are literally sitting ducks at night. Also, space. They need plenty of space. My big girls have an area that is 23' x 40' and that is the minimum I would ever have again. That includes a 10'x17' run/house area that they always have access to. I let them out of the run in the morning into the 23'x40' yard and then lock them up again at night. They weigh about 6-7 pounds each and that's about how much liquid waste they each expend daily
My area is 306 sq feet per bird and includes their house and run.
I've gone through extensive renovation of their house last year and decided for the non winter months to have play sand inside their house. It is much easier to clean (pooper scoop 2x weekly) and I don't obsess about all those wood shavings that constantly need to be replaced. In the winter, they will have wood shavings again and I'll just have to change it twice a week and then compost it all in the spring!
I've got two bantam ducks coming in the fall and their space will be a little over 860 sq feet total. Since they are bantams and about 1/3 the size of the big girls I will probably only have a max of six birds in that area. I am building them a predator proof house/run out of hardware cloth. It will be 4' x 14' and include a 4' x 2' house, 4'x5' pool area and the area in between will just be a wire enclosure.
After my big girls are gone, I think I'll stick with bantam ducks.
Since you live in the desert all the liquid waste probably won't be as big a concern for you as it is for me in MA but the more space they have the better is my opinion.
If you do a "duck housing" google search you'll be amazed at the number of sites that pop up. Good luck and happy searching.