You would not need to drill a hole...I have tubing running from the pump in the pond to the filter outside the pond. It just goes up over the edge of the pond. I built a shelf to hold the preformed waterfalls and the tubing runs underneath and is hidden by the waterfall and rocks. The tubing then goes from the filter to the top of the waterfalls. Same thing, it just lays over the top edge of the waterfall and is held in place by rocks. The nice thing with the preformed waterfalls, they come in a lot of shapes and sizes...I have a stream one that I use in the birdcage for my birds' water. I have two main waterfalls into my pond...two tiers on one side and three tiers on the other. I used rock and footpath stones to build the shelves to hold the waterfalls. That way the shelves were more open underneath so I could plant plants under the bottom and have a place to run the tubing. I had clear tubing in my pond for a while, but it turned white and grew all sorts of algae inside. I switched out to all black tubing and now I don't have to worry about the algae growing inside anymore...no sun = no algae. I prefer tubing over
PVC pipe simply for the flexibility. You may want to get the no-kink tubing. I didn't and I had to put some 90 degree elbows where the tubing really kinked. It worked out just fine though.