A plumber came to my house to unclog my kitchen sink. As he was leaving, he glanced at the plumbing under my kitchen sink and said something was not done correctly, but I don’t remember what he said was not done correctly. Can anyone spot any obvious problem with the piping under this kitchen sink? Thank you!
The correct plumbing is one P-trap for both sinks like this:
The horizontal slopes down to the P-trap by 1/4in per foot, and is above the exit into the wall.
There should be no chain of P-traps as your picture seems to suggest. Trapping each sink separately and joining the drains after the traps is allowed.
IRC 2017:
P3201.6 Number of Fixtures Per Trap
Fixtures shall not be double trapped.
When emptying the far sink (the one further from the exit), so not when just running the tap, the velocity and siphoning can empty both traps, and there might not be enough residual trickle to re-fill the near trap (the one near the exit, second in chain) through the far sink, exposing the home to sewer fumes through the near sink.
The disposal side of the sink is "double-trapped" since there is another P trap in the other sink outlet, that this one empties into.
There should not be a trap between the two sink halves. The only way to correctly have a trap per sink bowl would be if they each directly connected to the drain, NOT one output connecting to the other input.
There are plenty of issues. The water supply lines shouldn’t be under the drain line. The disposal should not have its own P-trap, the electrical outlet should be a gfci
