First post...I typically use a Gatorade bottle for occasional night emergency breaks. After all, who wants to get up when it is raining in the middle of the night? I searched prior posts and didn't find a better container. From my research a typical average volume per void is 250-400 ml (2 cups). I have seen some collapsible water bottles with wide mouths which will work for males. Any recommendations for weight and collapsibility for storage in my pack?