Over Unity systems exist in the real world.

[finnsawyer]

The idea would be to have some way to open a hole and eliminate the surface tension so the water above the hole would flow out.  Then shut it and let the water build up again.  Not likely I suppose.

[jacquesm]

As soon as you eliminate the surface tension the water will flow down.

And if you try to prohibit that you'll have to pull a hard vacuum in order to get the water out and that requires work.