Many Noodler's inks are waterproof and have served me well even for legal docs.

I've even found a bunch of other inks that aren't advertised as waterproof/resistant that ended up to be waterproof depending on the paper. For example J. Herbin Perle Noire on meh paper.

I do fine with them as an everyday carry, my gripe is mainly when I get a new pen, paper or ink knowing that a paper might not like a certain pen or ink.