Water from Snow and Ice
It is more efficient to melt ice than snow as ice requires less energy, therefore less fuel, to melt. Melting snow may be your only option. If so, an easy way of melting without a fire is to fill your drink bottle with snow and tuck it up under your jumper/sweater, whilst on the move and our body temperature will slowly melt it.
If you are too thirsty to wait for a whole bottle full to melt, you should melt a small amount of snow first by rubbing it between your palms, over your mouth, and drinking the drips.
In some situations, you may need to melt down sea ice for water. If this is the case, old, blue, sea ice with smooth edges is what you need to look for as it will be low in salt content and therefore good to melt and drink.
In the absence of old sea ice you could sea water in order to remove the salt and make it good to drink.