Jeff,

My water bottle is a Wiggy's (yes the sleeping bag folks), 1 qt stainless that can be placed on the fire. Wide mouth. It is great for melting snow. Not so good for cooking, but I have the cup that fits over the bottle to fix the food while the bottle is on the fire boiling water or melting snow. I also have a MSR Titan kettle .85 liters and VERY light. In winter or cold climates I carry both in my ruck. In my lightweight day bag I carry a SIGG .6 liter stainless bottle with cup. Again, I "cook" in the cup and boil water in the bottle. There are several cups and kettles that would work, the question is to find one that works for you.

Respectfully,

Jerry