I'm interested in the answer about the pump, because I have similar
set-up and problem. I had thought of using a cheap sump pump, but don't
know if that will work.

I can tell you that you're right -- 1.5 feet of elevation won't do it,
although it will help. We have ours elevated almost three fit and it
still isn't enough.

The one really cool thing about our rain barrels is that we have them
connected by siphon using sump pump hose, so we can draw from and fill
to a single barrel.

Frances