So how hot is the water from these things? I'm wondering about plastic from the bags or the container leaching into the food. I wouldn't think it would take much heat for the plastic to start leaching? Anyone ever looked into this issue?
The water is whatever temp you are cooking to. Since most of the SV cooks involve meat, you're really not going to go above about 150. A corned beef brisket, for 2 days at 145, is incredibly tender. You can't take a tough cut, like that, and have it that tender in the smoker.
The highest I've ever gone was corn, at 180. The bags are not a problem, but the seal can be. It is recommended that you triple-seal your bags, at higher temps.