I have recently purchased a 10 litre semi-opaque (grey) plastic container which appears to be ideal for sous vide cooking. It was sold as food grade, freezer & microwave safe, and has all the relevant marks on the bottom to confirm this rating. It is manufactured from polypropylene and is (PP5) graded.
Looking online, all the other sous vide baths I see are manufactured out of much more expensive polycarbonate, and this container was a fraction of that cost. I assume here that polycarbonate has been chosen because it is more rigid than polypropylene.
I have tested this up to 85 Centigrade and the walls of the container flex and bow only slightly more than they do when cold. I doubt if I will sous vide beyond 75 Centigrade, am I taking a risk using this product here?