The answer is no.
We thought we should put that at the top because truly, under no circumstances, should you immerse your nebulizer tube in water. Some people—self-proclaimed experts on the internet—may give you the green light to submerge your tube in a vinegar / water solution and hang it to dry. However, this does not guarantee that every last drop of fluid will exit the tube.
Fluid can build up inside the tube from mild breathing residue or accidentally getting it wet when cleaning. Any water or fluid residue in the tube is a potential breeding ground for bacteria and contamination that can be breathed into the lungs. Explicitly, residue in the tube is a highway to bacterial infection.
You can try to hang-dry the tube if you see any fluid within it after use but if you see any discoloration, it’s absolutely time to replace it.
You can also purchase replacement tubes to be safe.