I have five different packs of varying size as well as the Altoid tin kit. I keep the two littlest packs in the trunk of my sports car, and the two next largest one each in my truck and camping van. The largest day pack is in my home along with the always carried Altoid PSK. In all of these kits except the Altoids PSK, I have a cup or pot along with one type of water carrier or another. Even my smallest kit which is made from a 4x6x3 Bagmaster holster pouch has a Sierra cup strapped to the outside.
Aluminum foil should not be considered a reliable water container but like I said in my earlier post it's plenty useful for other things.
I'm not sure those aluminum baking pans are such a good idea either as a primary pot in a small kit. I think the Sierra cup and similar small metal cups or pots can be carried easily either inside or outside the kit or on your water bottle.
If all I had in a survival situation was my Altoid PSK, I'd hate to have to rely on that container as a water boiling pot (what does it hold, 2-3 ounces?). I'd hope to find something I could make a bowl from and drop hot rocks into it to boil instead.
Edited to add photo of the Bagmaster based kit:
http://www.fenderforum.com/userphotos/photo.php?id=61668 Won't take the image but will go to the photo.