Ouch, that's a good point.

I'd think the single hose /apparatus would have much less exposure than most water supplies, especially over time. Maybe run the water for a bit before using?

I mean you could probably get copper piping to work on it with some plumbing skills and tools; copper is, as far as I'm aware, fairly inert in the human body. at the moment anyway.

I’m not worried about that. I have a counter top RO machine made out of plastic but the water comes out at nearly 0ppm TDS, and it flows through the machine slowly, at low temp, and for a short time. Whatever is in there is orders of magnitude less than you would find anywhere else, it’s basically laboratory grade pure water.

Which machine do you have? I’ve been looking for a decent countertop RO system without much success.

AquaTru. I'm pretty happy with it, purchased it used on eBay and put new filters into it.

RO Buddy is a good starter if you just want to try for 60ish dollars.

> laboratory grade pure water

"but that'll kill 'ya!"

I know you’re joking, but I do add mineral drops to bring the TDS back up.

Do you have a brand you like? I'm thinking of getting a countertop device soon and they sell a "re-alkalizes it" version but I don't know if that's "enough" and of the right type and I'd like to cover my bases in case it's not.

I sell residential RO systems. Industry wide the tubing is typically LDPE and the housings/fittings are mostly polypropylene. There is no real practical way to build a residential RO system without using these materials.

It's a trade off between different types of plastic / chemical exposure. Not really ideal but I suspect nearly all sources of treated water will have traveled through a similar amount of plastic to get to you.

Copper is avoided on RO systems because the post membrane water typically drops 1-3 points in PH and will slowly corrode and leech copper into the treated water. All post membrane fittings and tubing should be plastic/stainless, cheap brass fittings with high lead content are the biggest concern. This can be resolved with post membrane PH amendment but you then create a failure point that can cause heavy metal exposure or leaks if it isn't maintained.

You could build a system with steel housings and braided stainless hose but the size/weight and cost are not practical.