Cold PVC pipe, not hot (slower leakage). Plus the leakage has diminishing returns (it cannot leak the same amount forever, it is physically impossible).

seems like responses here were assuming you meant the french press somehow had chemicals, but you're saying that the coffee beans have substances that maybe a filtration system removing from the coffee makes it better? Can you source that, because people have been drinking coffee a long time and I don't think that's a concern. After all, coffee is a plant material harvested then burned grinded up and suspended in water. Like most plants it probably contains substances, which in great quantities could kill humans, but if it were toxic we'd know by now. Plus the fact that you can buy chocolate covered espresso beans, where you consume the bean entirely. That would surely be the most toxic no? Never seen a warning on those.

that'd be the cholesterol, and there's not a good link between it and blood cholesterol

long story short, transparent plastic containers tend to imbue their contents with a chemical called bisphenol-a (aka bpa), which is a compound similar to estrogen which may impact human physiology in a wide array of ways[0], or chemicals that are structurally related that aren't well studied but could be similarly damaging[1]. this applies to all transparent plastics and isn't specific to aeropresses

[0] https://en.wikipedia.org/wiki/Bisphenol_A#Health_effects

[1] http://www.motherjones.com/environment/2014/03/tritan-certic...

Leaching chemicals. Here's an article I found after a quick google search, http://myplasticfreelife.com/2011/04/bpa-free-does-not-mean-...

It doesn't mention heat, but I presume leaching increases with heat.

I think it's because it is possible for materials in certain plastics to break down in the presence of heat.