The Kitchen Sink Smell That Kept Coming Back Every Three Weeks

The Real Problem

I called a plumber friend, more out of frustration than hope. He asked two questions: did I have a dishwasher, and was the smell coming from the left side of the sink?

Yes and yes.

He had me look under the sink again, this time at the dishwasher drain hose—the ribbed plastic tube that carries dirty water from the dishwasher into the sink drain line.

Mine had a gentle downward slope the whole way. That was the problem.

“Without a high loop or air gap,” he explained, “dirty water sits in the low point of that hose. It never drains all the way. Just sits there in the dark, in a warm tube, and starts growing stuff.”

He didn’t know why it was every three weeks exactly, but he’d seen it before. Something about how long it takes for the buildup to get bad enough to smell.

I’d been scrubbing the drain, the disposal, even the cabinet floor. The whole time, the smell was coming from inside a hose I didn’t even think of as part of the “drain.”

The fix wasn’t about cleaning at all.