When you're piping the drainage for a 2-bowl kitchen sink with a garbage disposal, do you like to use a continuous waste (made up with schedule 40 PVC fittings) and one trap, or do you prefer to use two traps (one for the disposal, and one for the other sink)? What is the reasoning behind your preference?

Usually, I like to use a continuous waste with one trap - whether or not there is a disposal - to save a bit of space under the sink, plus I just like the way a continuous waste looks.

Today I did a re-pipe with a disposal and had to use two traps because the drain was too high to use a continuous waste.

I'm curious to know which method others prefer and why.

-Ken

in massachusetts, we can't use a slip fitting on the outlet side of the trap. so, i use a glue trap, a tee-wye above it with a street destanco glued into it. position this under the elbow of the disposer with the branch of the tee-wye facing the other bowl. a short piece of pvc with a street 90 with a destanco glued on it. the only slip joints are the disposer 90 and the strainer tailpiece. you couls set off an M80 under the sink and not have any leaks.
we are also required to have a cleanout under the sink. either a wye with an end clean out or a test tee.

I suspect two traps would usually be the preference in Wisconsin since code does not permit the dishwasher connection via the food grinder.

So you would have trap #1 serving the food grinder & bowl #1 and trap #2 serving the dishwasher and bowl #2.

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Links to the State of Wisconsin Plumbing Code:
[docs.legis.wisconsin.gov]
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I am not a plumber.
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wisconsin won't let you tie a dishwasher drain into the disposer. the disposer comes with a factory inlet that is made for that purpose. nobody better make fun of massachusetts regulations after hearing this one.

Isn't Wisconsin the State that allows a lav trap, let's say for a pedestal basin, to be in the floor?...with a distance of 60" from the pop-up stopper to the trap, go figure.

I bet that set up will smell like a bed of roses in a few years.

e-plumber
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This slow drip will waste 7+ gallons of water per day.

The continuous waste is the easiest and fastest, although some "new house" plumbers in this area like to make their own waste out of schedule 40 pipe and fittings. Probably to make it difficult for the homeowner to work on it. Some inspectors have a problem with two traps, because the vent would not be connected between them.

Some code specifies that you can only have 1 trap on a trap arm.
Deb
The Pipewench

what in the world is there for a homeowner to work on? when the slip joints loosen up and leak, then a homeowner has to repair/replace something. when the double bowl set-up is sched 40 pipe and fittings and the trap has a cleanout on the bottom and there is a full size cleanout as the drain enters the wall, (as i said) you could set off an M80 and not create a leak.
sched 40 below the kitchen sink is helping the hownowner not hindering them. that is the only way i pipe a double bowl sink.

Well, when they run artichoke leaves through the disposer and the plug up the waste and trap, that is when they have to service it, and most of the 1 1/2" sch. 40 "P" traps with a union nut can only be taken apart acouple of times, if that many, before the nut cracks, especially if the installing plumber did a "good job" and applied pipe dope to the joint and threads..