If it's PET then it should be okay. All my Better Bottles are PET. Now, these are only good for 3 - 4 months as PET will show oxygen infiltration after that time. Bottles are usually labeled on the bottom for plastic type, although you may need to look up the code.
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.
I checked yesterday at homedepot - the Primo water bottles they sell/exchange are mixed. The older bottles are #7 other, newer bottles are #1 PET/PETE. The newer ones also had handles that were attached, so I think sediment wouldn't get caught and be as hard to clean.
Northern Brewer sells a six gallon food safe #1PET/PETE that is rated for winemaking. It has a 5" opening so it's super easy to add oak chips, etc. I have two of these, I ferment in one (it's nice to see through the bottle to see what's going on and I do the first rack into second plastic carboy. The plastic carboys are easy to move around and they won't break. The third rack goes into a five gallon glass carboy because by that time, you have close to a gallon of sediment/lees. The good thing about the glass carboy is I never have to top off the level as it usually fills it to the top.