ID plumbing setup, please, I'm baffled xpost
What is this contraption under a vanity sink? The black tube to the right leads up to nothing behind the vanity drawers. Another vanity, installed at the same time by the same plumber, has the same thing.
Can I safely cap that black tube off at the white pipe?
The gray tubing is supply line for hot and cold.
House was built in 1890s with mods over time in a town that had lax to no codes or inspections ... don't think "they'd never put ___ there", because they just might have.