I left this filled with water overnight while horizontal and it didn't leak. Have also tried shaking it upside down and didn't see any leaks. Caveat is that I haven't tried to microwave or freeze it yet, which could maybe lead to seal deformation later, but time will tell. I wonder why they didn't just print the "eyes" of the bird on the bottle itself? The included "sock" has the eyes, but because the threads weren't "finished" neatly in the back, you can kind of see them, through the white fibres. Like a bird with dripping makeup on. Kind of funnier because of this. Inside out, the sock looks a bit clown-ish. I wouldn't feel confident putting this sock in the machine wash because I'd guess the eye/beak fibres would all fall out.

Fun little duck design that has nice fabric and feels great on e filled with hot water. Will be buying again for my friends in India :)

These are great little water bottles. My kids love them. They stay warm for a very long time. Perfect for those winter months

Love these water bottles. They look great and keep warm for a very long time. No leakage

It's smaller than I imagined, but it's cute and works fine. The beak sticks out a bit too much so it's only good to use facing away from your body.

Super cute design. Nice material!