Polypropylene is not the worst choice, it still has chemical leeching potential. But I don't know what other options there are, every water filter I have seen has some plastic in it, and most are all plastic.

Not sure how much it matters if it's traveling through plastic pipe anyways. I'm back to using my plastic water filter, the tap water just tastes bad. But now I get it out and move it into glass to chill in the fridge. It's not perfect, but contact time is a factor.

My ideas at this point are to purchase a glass or steel cylinder and fill it with filtering stones/sands/sediment of varying sizes along with activated charcoal and just change out the layers as needed (particularly the charcoal). It's like how the ground filters water naturally, or getting glass labware to distill water and adding back in minerals. The first option doesn't get everything, the second is a pain in the ass.

Sorry, just kind of spit balling. I don't have a fantastic solution here. Sure would like access to a nice clean spring or well and not have to fuck with it at all.