Recently, I discovered that our OEM Dometic refrigerator white plastic drain hose was quietly disintegrating "behind closed doors" and I was surprised to learn that these hoses often begin to do so after only 3 years of age!
I was also surprised to see little mention of this in this Refrigerator sub-forum
. If your Airstream is over 3 years of age, you might want to inspect this item at the beginning of your camping season each year.
Our old plastic drain hose fell apart in my hands as I was removing it. It was replaced with superior quality reinforced vinyl tubing that should last many years.
I saved the old hose's perforated drain plug (which prevents critters from entering the hose and refrigerator). You'll be surprised to learn how much it costs to replace this little piece of plastic!
See the whole story and photos in my post, "RV refrigerator drain tube failure