The code used on plastic has nothing to do with whether the FDA considers it food-grade.
I will repeat. The code 1 (PET, polyethylene terephthalate), 2 (HDPE, high density polyethylene), 3 (V = polyvinyl chloride, or PVC), 4 (LDPE, low density polyethylene), 5 (PP, polypropylene), 6 (PS, polystyrene), 7 (other) describe categories of plastic, not whether it is food grade. Since different plastics have differing properties, e.g. ability to handle acidic substances,
Food-grade plastic does not contain plastic or dyes considered harmful to humans.
You can find recycled plastics used for food-grade plastic, but the FDA has some pretty tough guidelines. One of the major issues is that the previous use of the plastic may have had chemical or biological contaminants which could find their way into food-contact situations (or in our case, wort or gran contact situations). Here's the FDA guidelines:
Guidance for Industry: Use of Recycled Plastics in Food Packaging: Chemistry Considerations
Rant on: I've seen a s__t load of threads on using cheap buckets from various sources. Places like the HD "Homer" buckets. I really don't understand the point when it is fairly easy to go out and get "known good" buckets!
1. Go to a bakery, dunkin doughnuts or other places that get bulk supplies in food grade containers.
2 Go to a organic food market that sells things like agave or maple syrup in bulk. These come in food-grade containers.
3. Go to Walmart and buy the white buckets for $2.97. The ones from Encore plastics had been verified by the manufacturer to be food-grade.
I'm sure there are lots of people out there that say "Hey, I haven't gotten sick". Remember that many of the issues with things like heavy metals or chemical contamination won't show up for many, many years and will essentially be untraceable back to the fact that you used a homer or whatever bucket.
Well, maybe I should stop posting this stuff and just leave the sources for cheap, SAFE buckets to myself.