I have 2 old but barely used bottles. I could do with using them to store boiled water in the fridge. There is no reason why I shouldn't is there? They are about 4 years old, I wouldn't need teats on them, just the screw lid.
They won't be BPA free. I had some tommee tippee ones 4 years ago and that was before all the BPA stuff came into the news. If they're clear (or the tinted blue/pink ones) then they will contain BPA
However it's not an issue if you're using them to store cool boiled water, only if you're putting boiling water in them or heating the bottles with liquid in. If the bottle gets warm the BPA chemicals can "leech" into the contents and this was found to be harmful.
I used mine as "cup" measurers - 8fl. oz = 1 cup Makes US recipes easy to make! I have no idea where they all are now, though.