After the RO layer should exist another activated charcoal layer. This should block most of the leaked polyamide from the RO layer. My filter is this way.
You point to the membrane as a leakage source, but most RO systems also use flexible hosing in the assembly and from past work in medical devices it seems that flexible hosing is also a huge source of phthalate leakage.
Is that something that is also taken into account in higher end RO systems?
https://www.pbs.org/newshour/science/scientists-find-about-a...
I guess it’s possible to distill the water and add clean minerals back in. (Not sure if “clean minerals” are something that you can obtain though.)