The three phases of matter can exist together in equilibrium at the

... at the unique combination of temperature and pressure that's called the "triple point" of that substance. (It's different for every substance.). For water, the triple point is zero C (32 F) and about 0.006 of sea level atmospheric pressure. At those conditions, you could have ice, water, and steam all in the same jar at the same time.

Efficiency is an act of doing something