Posted: 15/05/2012 at 00:21
It's your call Dovefromabove. Pressure treated wood has rather nasty chemicals in it. That does not make it 'unfit for purpose'. If it wasn't treated against rot you would have to do it yourself. Use compost bags to line the beds, they are pretty strong.
Depending on high the raised beds are you will find out they dry out very rapidly if they are not lined, and as been mentioned above the wood will rot more quickly, as it surely will. If you enquire specifically you will find the wood preservative protection is not guaranteed for very long. That is the nature of the beast!