In terms of dissolved minerals sure, but there's two important distinctions to make. The tank isn't just accumulating deposits, there's an anode rod inside that's designed as a sacrificial element to protect the tank itself from corrosion. That anode rod gets consumed over the course of a decade so while it's not much, it is being introduced into the water. Also those deposits provide a porous substrate for bacteria to grow on and the heat will help things along.