I went snowshoeing this weekend in -10C (about 10F) weather. The previous weekend, the hydration tube on my Dromlite froze solid in similar weather and I figured to fill it with hot water before I set out to prevent freezing on this trip. I heated the water to about 150F and filled the Dromlite with space to spare and slipped it in my pack. All was well until I got to the trail head and put the pack on. A couple seconds later and I could feel hot water gushing out of the drain grommet hole at the bottom of the hydration sleeve on my pack. Ripping my pack off and pulling the Dromlite out, I noticed that the fabric of the bag had become delaminated from the outlet hole plastic at the top edge leaving a 1" hole where water was welling out. Utterly unrepairable either in the field or at home. My best guess is that the hot water had melted the glue there and lifting my pack had put just enough pressure on the top of the seal to cause the rupture. Luckily I had worn wp/b pants for extra heat retention and put the extra clothes in my pack in a garbage bag. And it's a good thing this didn't happen on a multi-day trip or in colder weather. My advice is not to rely on this style of hydration bag in either very hot weather or using hot water for cold weather. Using hot water when cleaning this hydration bag may also cause the same problem.
