Actually, substances can exist in all three states of matter simultaneously if the conditions are right. The triple point of a substance is the temperature and pressure at which all three states occur in equilibrium. Water can exist in natural environments in all three states of matter -- solid (ice), liquid, and gas (steam or water vapor).

By the way, when you put ice in a glass of water to create "ice water," the ice and water coexist awhile; that is, the ice stops melting. Water in both liquid and solid forms exists in the glass. The temperature of the ice and water is just slightly above zero degrees Celsius.