Today I inspected the drain and trap under the kitchen sink. I haven't really had any specific problem but I guess the drain could be faster. Sometimes I start the disposer to make it drain quicker. I have spotted some sort of grease leaking out of the trap and I will clean that up but my question is – is this an optimal drain plumbing? Something seems off in this installation but maybe it's just my lack of experience.
On the right side, difficult to see in these particular pictures, there is a copper pipe section that goes down to the sewer and also up to a vent on the roof.
Please, forget the section of drywall I removed. I just wanted to see the hot and cold water pipes as I'm also trying to fix a water hammer issue, but that is another story.
Best Answer
This is what you need to do.
What you have is essentially a very long and deep trap seal. For a trap to function properly you need a seal (height of stored water) to be between 2 and 4". So from the bottom of the exit pipe to the bottom of the trap should be between 2 and 4". The reservoir of water should only be contained in the trap.
You want the drain to slope the entire way, 1/4" per foot is the only acceptable slope. This allows the waste water to wash the pipe. It swishies back and forth at 1/4" slope. More slope and the waste shoots down the center building up debris on the wall of the pipe. Less slope and it doesn't flow.
Most people don't know this for some reason but on a torpedo level half the bubble is 1/2" slope per foot, 1/4 bubble is 1/4" per foot.
Some levels have multiple indicators to aid in the measurement. In this case 1/8th and 1/4" respectively.
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