Risk from sucking obstructed condensation drains of air conditioners?

I am a heating and air conditioning service technician. Often the condensation drain lines on air conditioning equipment become clogged with a reddish sludge. It is necessary to clear the drain with suction to prevent blowing the material back into the drain pan. In the past I have connected clean pipe to the drain line and sucked the obstruction loose careful not to get a mouthful of dirty water. After reading the information on your site and another site, this method is obviously wrong. What kind of risk have I put myself in. and if there is a risk why don’t I know more about it.

The risk to you is obviously small because you never have gotten sick. But the sludge may contain germs or toxins that may enter your mouth accidentally. If they got into your lung (which is possible if you are a smoker) you might contract pneumonia. And, if they got into your stomach, you could get diarrhea. Except for convenience, there seems no advantage to using your mouth for suctioning. A vacuum apparatus would be safer (but probably less convenient). By the way, what method do you use for unclogging sewage lines?