It's all in code man. It's to keep you all confused if the US were to ever invade Canada. For example, Tim Hortons are really secret miltary establishments that house a giant mind control network.
OH ****.. is that CSIS at my door?
BTW, that water bottle was polycarbonate, but PET should work. Of course the bottom expands.
And if you look at the OP date, that was s 3 years ago and kegs here were $90 each. By Naturally carbing the beer it worked fine. I do advise a pressure release on it. Dispense at low pressure. And move on to really kegging as soon as you can. This was to hokey.
I no longer trust those tire inflators. To easy to have one dump 400psi into the the keg.