I've used water PET bottles for fermentation or a month or two storage. Disposable 4-gallon water come in these, I get them at Wegmans. They are pretty flexible, same as a 2 liter soda bottle. My friend uses the much thicker 5-gallon from Poland Spring, etc. He ferments and stores in those, not all are new PET bottles. I don't know what acids and alcohol does to that older type of plastic. Of course, he treats fresh juice like a kit- ferment, DualFine and bottled in 30 or 45 days. You might be ok, but not recommended.
I do know you could buy PET bottles as Better Bottle (wine/beer supply) or water jugs (somewhere else). DrinkMoreWater uses PET that is the same as a Better Bottle but with a handle. I also have those, less flex than thinner types, but still do not store as long as I do in glass. I just don't like that my airlock sucks in sanitizer when they are moved.