In a frozen environment, keep your water container(s) only about 2/3 filled. Use small containers, so that the surface area to volume ratio is high. 1 gallon containers take forever to melt, but several 16oz water bottles melt faster.
All you can do to make the water into liquid, is:
-Keep the bottle(s) inside your clothing, where it is above freezing, so the water can melt
-Melt the water using a heat source such as a camp fire
-Keep the bottle inside your sleeping bag at night.
If your area is only borderline freezing, you could probably put a SMALL amount of alcohol into the water to keep it liquid. Not certain what effect that would have on the value of the water as a tool to fight off dehydration though, since alcohol encourages dehydration.