I used a 2L Zip-mouth Platty & 24oz or 1L water bottle for the entire AT this spring. worked great with lots of options. No leaks. MY camelbak bladder has leaked at connectors. And it's heavier.
HOWEVERR-My platty HAS soaked my pack though-when I've set it down in cars or layed it bladder side down on the ground and the pack weight squeezed water past the bite valve. For most of the AT I used a bite tube with a stopcock valve to try prevent this, but with enough pressure you can still force water by it. In spring/summer this risk isnt a big deal, though I'm much more cautious about it, usually not filling my bladder until I get to the trailhead vs prior to packing it in the car. (Or keep the bladder outside the pack)
I find the zip-mouth opening MUCH easier and faster to fill from fast,deep sources or shallow ones. Still, I have had to use my Tit mug/pot more than once to fill it up even with the zip mouth. Used to carry the straw filter for backup, finally mailed it home from the trail, may carry it from time to time as the "ultimate option" to drink from a mud puddle that you could otherwise not fill up at. (You get cocky on thru hikes and take calculated risks in good weather when you're not far from anywhere)
Like previous posts I vary which platty size or bottles I bring depending on the trip. I now typically carry a 3L Platty cuz its more versatile-can fill it 1.5L to save weight or 2L for practical happy medium. Or occassionally fill the whole 3L for dry spells or in camp. I still carry spare water bottle (lite and cheap)
Last weekend on a snowy VT hike in the 20's by day, teens by nite illustrated the importance of backup containers. I blew into the bite valve to push the water out of the hose and back into the platty overnite to prevent the hose from freezing but awoke to find frozen BOTH my 3L Platty and my 1L water bottle into a solid-block of ice-overnite. Luckily I had only a 3 mile hike out on my last day. But I thought "What would I do if I still had a several day hike out?"
So I boiled snow in my pot to make water but had no room in the bottle or bladder to pour any hot water and a few ounces wouldn't have done much anyway to the 3L block of ice. It sure would have sucked carrying a block of ice I couldnt even use (with no hope of it melting by day! I further considered that I would likely tear the bladder if I tried breaking the ice by repeated blows)
Luckily my 1L water bottle diameter just fit inside my pot so I parboiled the bottle of ice until the ice melted inside. The top of the bottle melted a little but was still functional, but I almost melted it too much rendering it useless. Whew!
Sure wished I'd brought the 1L Platty I had at home!
So THAT's my new plan. Gonna carry at least one EMPTY 1L Platty with a screw on cap as a backup container. IT literally weighs only 1oz. Gonna bring screw on caps for my bigger bladders and disconnect and empty the hose overnite.
Still paranoid to sleep with my big bladders for fear of a leak, considered pouring out half the water before nite leaving a little room for adding hot water to melt any ice block that might form overnite or try to find a source to top it off with water. Also not keen about sleeping with cold water wicking away my body heat (when I really want to sleep with extra clothing for dead air space I can warm). Probably will wrap something around my bladder & place it under my feet maybe between 2 sleeping pads to help prevent it from freezing. But I'm sure this won't always be enough.
The EMPTY backup 1L Platty will bring peace of mind at minimal cost in weight or space on winter or multi-day backcountry trips where the margin of error could matter.
(sorry for the ramblings)
