I am curious as to how detrimental a connection like this could be. I see them all the time. They start at the evaporator coil, properly trap the drain line there, run the drain pipe downhill to a tailpiece under a bathroom sink and connect it before (on the sink side not sewer side of) the trap. I see it installed this way on every single new home an many older homes in my area.

What would the worst case scenario be for this type of indirect waste connection if it is properly trapped and configured. I do not buy into the bacteria from the evap coil condensation either, algae maybe, but I am sure there is already plenty of bacteria floating in my bathroom sink p-trap from brushing my teeth, washing hands, etc that would be far more dangerous than bacteria growing in the water of the condensation drain.

I ask this because I inspect in several jurisdictions who use diferent editions of the code, and they all allow this type of connection, regardless of what the code states (and yes, I have contacted the BO reps directly to ask them if it is accepted). On some houses that are ten years old or more I have seen this type of connection and after ten years could not detect a problem with the configuration.

If it is a real problem to do it this way, why is it allowed by so many jurisdictions, and obviously, not just in my part of the woods?

Just curious.