I've been doing some research for an aquaponics system and I see so many videos where people are using PVC over the last few years so I started doing some research a while back and thought I would share my findings on the topic.
PVC(polyvinyl chloride or vinyl) and CPVC(chlorinated polyvinyl chloride or vinyl) and the cement used to join it is not safe for food use, not safe for grow beds and not safe for aquaponics. Three years of research on this topic now and I have a significant number of research articles outlining the known human carcinogens in PVCs and how they leach into fish tissue, food and the water when used in this environment. Many of the cheaper imported PVC's also contain lead, mercury and other even more harmful chemicals.
PVCs also contain Phthalates, which are endocrine disruptors and cause malformation on male reproductive system.
The plastic food grade totes (polyethylene) is fine unless it is heated, for example sunlight can cause polyethylene to leach antimony(a toxic metalloid) into food and water,
HDPE Plastics like milk containers
LDPE plastics like bread bags and the shiny lining of cardboard food products like milk cartons
Both leach estrogenic chemicals which can cause a lot of issues for fetuses and juveniles with respect to hormone imbalances and trigger auto immune disorders.
The other options that I've seen is to use bamboo, copper with lead free solder of course(copper is not eco friendly and can react with some things so may not be the best solution either, also somewhat expensive), cast iron(however it will rust, is heavy and expensive to install).
I've also seen some info on PP(Polypropylene Pipe) they use it in the EU and have for 30 years now as water supply pipes but I have not done any research on it so cant give good or bad advise on it.
Other thoughts, food grade silicone?
In the end I think bamboo for pipe offers the most economical and healthy option as its becoming more and more readily available here in the US. Perhaps whisky barrels for the containers rather then the some of the plastic drums that also contain carcinogens which people are using today.
I've seen it mentioned that bamboo with fiberglass/poly cured joints may be the best option at this time as the bamboo is fitted and only a very small portion of the fiberglasss/poly is in contact with the water flow since its wrapped on the outside of the bamboo joinings. This lead me to thinking why not use natural rubber, you know... from a rubber tree to seal joints with bamboo for pipe and wooden barrels. The issue however is some people have reactions to natural rubber so another solution that may work in the not to distant future is Guayule Latex which is Hypoallergenic and completely safe as well as native to North America but quite expensive to harvest and process.
This article is a work in progress and you should do your own research before choosing a material to use for your garden aquaponics system.