DWV Concern: Kitchen Sink Drain by John Bouldin

This month we'll look at another DWV issue, this one involving a kitchen sink drain. The attached photo shows a kitchen sink trap that appears to have been modified to accommodate the retrofitted disposal. It resulted in a very deep 'trap', which allows the accumulation of water and disposal debris inside the tailpiece and disposal. The problem wasn't hard to detect - the smell nearly knocked me over, which is not surprising given the potential for decayed material and bacteria growth in the system. The IRC addresses this concern in section P3201.2, and specifies that the depth of the water seal in the trap must be at least two inches deep, but may not be more than four inches deep. I estimate that the trap seal depth for the drain in the photo is closer to twelve inches deep (the distance between the two horizontal lines in the photo), taking into account the length of the vertical pipe connecting the trap to the drain pipe in the kitchen wall. It appears that the trap system could be made to work for the two sink bowls alone, but will not work with the current configuration of the disposal.

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