If you peel off the original label and write on the bottle what's in it. There shouldn't be an issue with re-using PET bottles for chemicals. Don't know about you but I don't keep my chemicals in the same cupboard/closet/room as my drinks.

What photo chemical contains strong lime that corrodes a PET bottle? I've noticed that the Se-toner bottle has become more brittle. But it's easy to get another bottle and put the stuff into a new bottle.