Unless the original contents label is still on them, I'd be real cautious. A black barrel could still be dangerous. Most people want $50 or so for barrels that are food grade. The fact that they are white is promising, but I once saw some kind of acid being shipped in white drums.
BPA is usually used in the very hard plastics like polycarbonate.
If you are reasonably sure that they weren't used for something else (like "water barrels" for sale at a pesticide company) and you clean them out really well - REALLY FREAKIN WELL - then you might use it for a counter balance on a trebuchet. But I wouldn't drink out of it.
The 55 gal drums I bought were used to ship al-kee-hall of the adult beverage variety. Original label still on the side.
Quite a pungent aroma during cleanout.
Think I gave $15 for them.
Know what was in them before buying, and you should be fine.
If unknown, pass.