Hi Shaun and welcome to Orchid Board
I wonder if instead of Water Culture a Semi-Hydroponic (S/H) method would help for your dry climate. This is a method which has a constant resevoir of water in the pot and uses an inorganic medium which will not rot.
We have a whole section of the forum here discussing growing in this method and I think there are a lot of our members who either grow this way or have tried it (I have a few I'm trying just now). Not sure if anyone has done it for outside plants or not but it might be worth asking over there.
Here is a link giving details of the technique to get you started. Ray whose website this is from is a regular contributor here on OB.
Semi-hydroponics