Long ago, an evil warlock kidnapped a Dwarven smith and forced him to craft a robot soldier. Yielding to the torture, the smith created Steam Activated Mechanoid, or S.A.M. for short.
One day after a rather brutal streak of destruction, S.A.M. was refueled with some contaminated water. Instead of breaking down, the water miraculously caused the automaton to become self-aware.
Immediately developing a conscious, S.A.M. turned on the warlock and rescued the Dwarven smith. The Dwarf brought it back to him home under the mountains, where S.A.M. replenishes itself with only the purest spring water.