Plane water is really nasty. Even Sudden made it will not taste great. You can mix Sudden with cold water by shaking it in a bottle and that's what I usually do when traveling

> I'm not a frequent first-class passenger, but if I were, high-quality coffee would be a big deal for me.

Many transatlantic and transpacific flights now have a proper grind-on-demand coffee machine (allowing for lattes, cappuccinos, etc) in business / first class. Doesn't necessarily solve the water problem, although they can fill them up from bottled (I don't know if they actually do).

Definitely looking to do plane coffee at some point but the water quality remains biggest issue.

I don't think I've ever been on an airplane that served "tap water". It's always been bottled.

drinking water is but hot water for brewing coffee comes from big tanks that get really gross