I bought a Nalgene 32oz bottle. http://www.llbean.com/llb…739-Google_Base&subrnd=0
This is a good size in that it will fit in a 5 inch cat bag. Add some bandages, antibiotic ointment, tweasers, gloves, saline solution, and a first aid blanket. If you have any other special meds. that you need you can add them.
I have carried this on my boat for about 5 years. It has always stayed dry.
