Not necessarily. I doubt you could taste particles, unless they are truly molecule-sized nano to be able to bind to taste receptors? I think you need molecules. Which plastic bottles, depending on the exact kind of plastic and how it was manufactured, may have plenty of - it's not just the ideal "plastic" material, the carbon chains, but plenty of other kinds of molecules dissolved in between. In text books the different kinds of plastic are always represented with the main molecule - but not just is there no such thing as a 100% pure substance in a real-world manufacturing process, in addition all kinds of other molecules are added deliberately - temporarily during a manufacturing step or to become part of the final product - to modify the physical properties of the substance. So even the same kind of plastic can contain very different kinds of other substances depending on who made it when and where.
I’d wild-ass guess that it’s using a cheaper water treatment? If you don’t want your water going green on the shelves, you need _some_ solution, and I’m guessing a dab of chlorine or similar both achieves that and makes the water taste weird.
