Underwater Breathing

[arcFlash]

So I've been told that in a near drowning that one of the recovery issues is the lungs don't work well and people die after being saved from the water. They said the lungs have a thin coat of mucus to kept the tissue from sticking together and it prevents irritation while breathing. The aspirated water removes this mucus and caused problems.

So if that's reasonably correct, how does this system replace the washed out mucus? (I assume its also a barrier to infection but that an easier issue)