Funny, I was thinking about the overflow port & kitchen sinks as I watched my DD over-fill the bathtub last weekend.

I don't think I've ever seen a kitchen sink w/an overflow port...bathroom sinks & tubs, yes...all, but never in a kitchen sink!

A true Belfast sink has a Weir drain -- a little doorstop wedge to the side. But not the London sinks we get.

Do standard stainless drop ins? I don't think so ... Do they?

I'm Gaslighting myself now ...

My stainless sink has an overflow. Its a little series of 4 1-inch slots about an inch below the top. It gave my plumber fits because it has a pipe thingy attached to the back of the sink (where the slots are) that attaches to the p-trap. Making it work around the disposal was the problem, I guess.

I don't know if this makes a difference, but my sink was made in Canada.

I read somewhere that we don't have overflows on kitchen sinks because of the possibility of food waste getting where you couldn't get at it and possibly smelling. Food waste isn't a problem in the bathroom. This could be bunk, just something I read awhile ago.

Most double bowl sinks don't need an overflow port as the bridge is usually low enough to allow water to flow over it into the other bowl. I can imagine horror stories in years to come.

But that doesn't mean I don't want one!

Growley had it right. Belfast sinks use the Weir overflow which requires a special drain part, not available in North America. it's a code issue. We don't require overflows in kitchen sinks, so manufacturers don't bother.