regarding leaking Nanos:
Found this somewhere - here's what fixed it for me!
A) Don't fill it ALL the way up - there's some kind of air-pressure thing going on in a Nano, and it needs a little air. I'd say maybe 80-85% of the way up (in comparison to the height of the center tube)
B) GET THE MOUTHPIECE ON QUICKLY. For some reason, open while full promotes leaking!
C) DRAW ON IT RIGHT AWAY. For some reason, getting an initial suck on the thing immediately after filling also seems to help.
Not intuitive, but these steps don't take any effort, and seemed to solve my leaky Nano (which sounds like a relative you don't like to visit).