yes, that is what I was trying to say. If the pond is sealed properly, it won't let water out OR in. Best to have that spring flowing in from the top surface.
I still would not rely on a spring for the water source. Consider it a bonus.. Things change. Your pond being 20 foot below his could actually drain his more (relieving pressure point). Same goes for that plant. If they decide to pull more water, it could affect everyone else, without much recourse.
