Does anyone worry that nuclear fusion could use all our water supply?

As society advances, energy needs expand - this is always true.

Currently scientists always seem to say that nuclear fusion would give us unlimited energy, which is simply not true - eventually we would run out of matter to fuse.

Obviously we would be using hydrogen initially, which makes up water. I guess current energy use would mean it would last a very long time - giving us enough time to mine water from other planets.

What if with the advent of nuclear fusion, developing countries became modernized with this new energy source, and the worlds energy use grew at an exponential rate, until we had the next crisis on our hands - running out of water?