So I have noticed this recently in the Manufactio pack where when I place down a pump and start placing the pipes it operates properly as in it doesn't start collecting the pollution until after it reaches the default range of 16 for the pack. However, after it has reached that level if you take the pipes down it doesn't matter if you knock the pipes all the way down to 1 pipe on the pump it still will collect pollution at 127 until you break all of the pipes or the pump itself. Is this a bug or intended?

I tested this when I created the blocks, but yes it should always collect at the top of the pipes.
I'll try reproduce this at some point.