Sounds like it might be too late now to drill it, but if you can, Stacy, definitely drill it. I know every setup is probably a little different, but when my pipe is just draining - not siphoning - there is very little airspace above the waterline inside the 45 degree elbow. If I had a 4' extension on mine, I think that elbow would be entirely full. Then if it froze, the pipe would be plugged and unable to drain at all.