I doubt rust is an issue in the compost. In a perfect world...however there is iron oxide (rust) in the soil and plants grow in it, without issue. We eat vegetables grown in red soil. It's the main mineral in red blood cells and we would be dead without iron. I would be more concerned with galvanized screen or hardware cloth.

You could try stainless steel screening which you might find at a boating supply, pool keepers supply, or an industrial hardware supply, locally. Otherwise, it's the web pirates.

Fishing line works well, get 100# test ;)

I just built one like this and used the white coated wire shelving for the bottom. This is usually coated with vinyl. A brand name is closet-made.

The PVC won't leach under standard temperature and pressure. But I have seen may people posting that the pvc sags and fails then dumps the bin on the floor.

I have also seen many designs where heavy fishing line or string-trimmer line was used. Expect it to sag and make sure your knots are solid.

I would expect galvanized wire - such as bailing wire - would be great to use also.

Any kind if line will sag, and it will be under tension. The tension will pull the sides if your bin together, causing the bin to deform.

I have not had problems with PVC sagging. I guess it depends on how big the pipe is and how long the run is.

I would not use anything galvanized. The zinc kills fungus, etc. Also don't use any sort of screen. You will have a very difficult time harvesting. You want all of the structure, whatever it is, running in the same direction.

I have had success using metal fence posts for flow through bins, which are usually easy to find and very strong, just make sure the hole that you drill is "tight" fitting. I don't think that rust is a big issue. I use PVC pipe which i drill hundreds of holes in for ventilation and have had no problems with it either.

Good luck

Bill

PVC is a kind of plastic. Did you mean galvanized piping? I did use galvanized electr. conduit for the grating of my bins and they are OK even with oxidation spots. It will event. collapse but not in my lifetime, I hope, lol.

I will remember sbryce's comment: ""The zinc kills fungus, etc."" but people building the DIY bins when not using weed whacker strings or PVC, used galv. electr. conduits. I guess these pipes couldn't kill the amount of fungus etc. the bins produce, let's hope so.