Safety of Vinyl for use in Nutrient Film Technique Hydroponic Systems
I am in the process of building an NFT hydroponic setup and had been planning on using simple vinyl rain gutter downspouts (from Home Depot, specifically https://www.homedepot.com/p/Amerimax-Home-Products-2-in-x-3-in-x-120-in-White-Vinyl-Downspout-M0593/100095267) for my grow channels. While searching for food safe sealants to seal the ends of the downspouts, I realized I hadn't yet considered the safety of the downspout itself. I haven't been able to find much in the way of research online and really only find what appear to be half-informed opinions in forums. So, long story short, is vinyl a safe material to use for growing hydroponically or will it leach chemicals that will be taken up by the plant and that I would rather not have in my food?
Washington County Oregon
Unfortunately, I haven't been able to find a definitive resource to help answer your question. My best suggestion is to use food-grade or food-safe materials for all surfaces that come in contact with the plants and the hydroponic solution. Non-food grade plastics can be used for drains or other non-contact surfaces.
We always recommend checking with the manufacturer about the food-safe status. For example, building supply stores sell five gallon buckets that are used in many hydroponic set ups but not all buckets are food-grade (usually this will be noted or stamped on the bucket if it is food-grade). The issue with using industrial building materials is that non-food grade plastics may contain dyes or resins (or chemicals that leach) that are not suitable for consumption. You may want to contact Amerimax directly and get more information on the components in that product.
We see similar questions from folks hooking up their roof gutters to rain barrels and then wanting to irrigate edible crops. Unfortunately, there is not much research specifically on the interaction of water, hydroponic solutions (pH issues), plastics, and uptake of any leached chemicals by the plants. It's just a big unknown.
Good luck with your system and thanks for using Ask An Expert.