No worse than cigarettes. I doubt you did any damage at all, even sucking up worms, fungus, and bacteria.
However, there is always a chance and if you start to have any signs and symptoms of a systemic infection (fever, aches, chills, nausea, vomiting, weakness) see your doctor immediately as well as any other symptoms that may relate to you inhaling water like shortness or breath, pain in your chest, coughing up sputum - this might be normal if it's the only symptom as your lungs are trying to clean out all the harmful stuff, but if it has a foul odor that could be a sign of infection.
Edit: Seems as if this is a somewhat common occurrence. If you are inhaling water each time you do a change and coughing/gagging for a minute afterward that could start to cause damage just from the mucousa and alveoli being irritated continuously. Again, that's long-term exposure (much like long-term smoking or drinking)... just be more careful when doing your changes.
Just to scare you there is a condition called "secondary drowning" where serious complications or death may occur up to to 72 hours after an incident because of the time the body takes to sense the problem and attempt it's own fix.
So slow down! You aren't trying to steal gas out of Bubba's 1983 Ford truck while he's picking up his momma. You have 20 extra seconds to slowly siphon the water :p
Last edited by SleepyRN; 07-10-2010 at 02:35 PM.