I just can’t help myself; I have to respond to this thread. But first, my bias – I am an organic chemist employed by a company in the plastics industry, so I am not chemophobic, and I don’t automatically distrust anything made of plastic. However, I will admit I prefer stainless steel when I can afford it. Now, let’s start with the recycling codes on the bottom of bottles, because some of them have been mis-identified in this thread. The numbers range from 1 to 7. Each number refers to a different recyclable plastic.
1 is for PET or PETE – polyethylene terephalate, commonly known as polyester. Despite the name, this plastic is not polyethylene, or related to polyethylene. This is the plastic used in soft drink bottles.
2 is for HDPE - high density polyethylene. This is one of the most common plastics, along with its cousin, low density polyethylene. HDPE is used in milk bottles.
3 is for PVC – polyvinyl chloride, commonly known as vinyl. This is used in some juice bottles and in PVC water pipe. Some of us use PVC pipe in our mash tun manifolds, and most use plasticized PVC tubing for siphon hoses and beer dispensing lines.
4 is for LDPE – low density polyethylene. This is commonly used in plastic sandwich bags, trash bags and plastic shopping bags.
5 is for PP – polypropylene. Commonly used in dairy product containers like yoghurt and cottage cheese containers. Also often used in the inner liners of the coolers we use for mash tuns.
6 is for PS – polystyrene. Commonly used in foam coffee cups and fast food containers.
7 is for “other plastics” most commonly ABS (Acrylonitrile Butadiene Styrene) and PC (polycarbonate), but any other recyclable plastic not in classes 1 through 6 could be labeled with 7. So, don’t assume that 7 automatically implies polycarbonate.
None of this is controversial, I hope. But, the next part is. In the context of homebrewing, most of these plastics come in food grade versions that are compliant with US FDA regulations. Some people take comfort in that, and use them happily; others are less trusting and are concerned about residual chemicals that could leach out of the plastic container and into the food (or beer) they come in contact with.
The most controversial plastic these days is PC, polycarbonate. This is because of the fears about bisphenol A, a monomer used to make PC. The fear is that the Bis A is an endocrine disruptor and might cause a long list of problems, mainly developmental. Frankly, I think the evidence is pretty weak for this, and the issue has been blown out of proportion by the chemophobes and environmentalists. If there is an issue with Bis A being an endocrine disruptor, then it is babies and children who are at risk. Those of us old enough to be homebrewing are fully developed (physically, and sexually if not emotionally) and are not at risk of being poisoned by using PC containers for beer making. PC is the only plastic that Bisphenol A is used in. The other place Bis A is used is as a monomer for epoxy can coatings, typically “tin cans” which are really steel cans, and beer cans.
Plastic number 3, PVC, was controversial in then 1970s due to its residual vinyl chloride content, but that has ceased to be an issue because PVC makers figured out how to strip it out before the plastic was made into articles. Now most of the fuss over rigid PVC is related to its incineration which may create and release dioxins. Flexible PVC does have its own controversy, over the toxicology of the phthalate plasticizers used to make the normally rigid PVC floppy. Sort of a chemical anti-Viagra I guess. Phthalates are also suspected of being endocrine disruptors, but again the evidence is disputable in my opinion, and like Bisphenol A, the main concerns are for developing babies and children.
Generally speaking the other plastics have few or no “chemicals of concern” for us to worry about. They do have some strengths and weaknesses in regards to their usefulness in beer making. Most of them are poor oxygen barriers. That is the main reason we counsel folks not to use them for long term storage of fermented beer. The exception to this is the type of PET used in Better Bottles, which was chosen because it does have good oxygen barrier properties. The ordinary PET (or other plastic if the bottle is labeled with anything except a 1) used in normal 5 gallon water bottles will very slowly let oxygen through into whatever is stored inside. It may be fine for primary fermentation, but a using one for a long secondary fermentation isn’t such a good idea, due to oxygen permeation through the wall of the bottle, and the subsequent flavor defects oxygen induces in the beer, or wine.
I agree with the folks suggesting that Better Bottles are, well, better than the ordinary water bottles. Not because I am worried about some chemical leaching out but because of the oxygen leaching into my beer. So, make your own choices, but remember the alcohol in our beer is more toxic than most of the chemicals mentioned, and don’t worry your brain cells into premature death.