There isn't really room for it—Dad prefers to put in those big coffee-can-style traps, and if we put one of those directly under the sink, it would lower the line enough that it wouldn't meet up with what it needs to meet up with on the other side of that wall. Instead, it's in the basement.

Keep in mind that that's a kitchen sink, so the drain hole has a strainer in it anyway. It should* be pretty much impossible to drop anything substantial down there. Should the line get clogged near the sink and the other usual use for an undersink trap be required, there's a cleanout on the left-hand end of the pipe right under the sink.

--G.
famous last words dep't
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Benjamin D. Hutchins, Co-Founder, Editor-in-Chief, & Forum Mod
Eyrie Productions, Unlimited http://www.eyrie-productions.com/
zgryphon at that email service Google has
Ceterum censeo Carthaginem esse delendam.