I have a similar smoker.
You want to always use the water pan and keep water in it while in use, though not for the reasons they give in the instructions.
It's function is as a heat shield between the fire and your food.
It does put moisture in the air inside the smoker and that slows evaporation of moisture from the meat. No way does it "put moisture into the meat", you can't do that.
Show us the brisket!!!!!
"If you can't smell smoke it ain't a barbeque joint" peculiarmike
"Life's tough.....It's even tougher if you're stupid."
- John Wayne