Minecraft isn't shy with mods. Modder David Joslin created a modification for minecraft that drastically changes how the water behaves. Calling it FiniteLiquid, rather than managing blocks of water, you go to the lake and take buckets of water. As you take your water from the lake, the volume of the lake decreases thereby adding a finite supply to the gaming world.

He's included pipes and pumps if you plan on building a modern world or wish to apply any other interesting mechanics.