Gaskets for tap/faucet for drinking water
This puzzled me. After some looking, I think this is referring to the NSF 61 standards, or a similar European/German standard. If that's the case, the phrase "for household, but not for drinking water" would mean that the product has not been approved for use in an industrial system that processes drinking water, but should be acceptable for household use.

In that case, I'd recommend just looking up the possible materials, and buying a gasket that uses a material you like the look of.