Geothermal heat is only produced by certain phenomena. There can be pockets of magma near the surface crust, but far below the surface in oceanic crust. Geothermal heat is utilized on surface crust by necessity.
As for the water supply question, I think the basis of your question is to find a passive geothermal system to maximize efficiency and output. I don't know about increasing efficiency, but I can imagine a possible passive supply of water to a higher elevation.
Consider a testable experiment. Put a cup of water on the ground, and an empty cup on a table. Run a copper tube between the cups, and about midway along the pipe place a candle. If you prime the pipe, and allow some time for the heat to create a pressure gradient in the primed pipe, it should result in a flow up the pipe from the water below, to the empty cup above.
If you scale this and do it right, you could use the concept to supply a geothermal source above sea level or a water table.