We're selling our house and one of the things we're doing to get it ready is putting double sinks in both of our upstairs bathrooms (house was built in 71).

The economical way to do that is to T both the water lines and the drain lines under the sinks as opposed to opening the walls up and putting in Ts there.

Is that ok by code or is an inspector going to ding us for that?

Thanks!

I'm not sure on codes... but that seems logical to me. I would "t" them into a single p-trap that feeds into the wall outlet.

Like this pic

i don't think you want to do it that way. both sides should have a easy path, doing it that way they fight each other

sts7049 said:

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i don't think you want to do it that way. both sides should have a easy path, doing it that way they fight each other

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Fight each other? It's going to have to tee somewhere. In the wall or outside the wall. The only downside to the picture is it doesn't look pretty. Putting it in the wall and two traps will look cleaner. Totally fine plumbing wise.

TECHNICALLY, code states that each drain must be 1.5" and then 2" after the tee. If you have an anal inspector, he'll call it out. But come on, how much water does each sink put out?

I would agree with you these are like 7"x13" sinks...not a lot of volume.

I think my guy can plumb it where it Ts into a 2" which will in turn T into the main

Do you think tere should be a little more fall in those lines in the pic shown?

So the consensus is not a big concern other than a spider of pvc in the cabinets?

That pipe sticking out of the wall is most likely 1.5". It would have to be 2", the trap 2", the drop 2", the tee 1.5x1.5x2" to meet official code. Most would do it like the picture, but like I said, depends on the inspector (if a permit is being pulled).

The Fife said:

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Only with shorter supply hoses.

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In my defense, this was a random pic I found on google while doing a cursory code search to help answer OP. This is not my undersink cabinet.

i would put the trap directly beneath one sink so it has a straight shot, then tee the second sink into that

sts7049 said:

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i would put the trap directly beneath one sink so it has a straight shot, then tee the second sink into that

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Agreed.

sts7049 said:

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i would put the trap directly beneath one sink so it has a straight shot, then tee the second sink into that

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This.

And use offset sweeps instead of tees to avoid backfilling in the event both sinks are running and there is constriction or slowing of draining.

schmellba99 said:

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sts7049 said:

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i would put the trap directly beneath one sink so it has a straight shot, then tee the second sink into that

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This.

And use offset sweeps instead of tees to avoid backfilling in the event both sinks are running and there is constriction or slowing of draining.

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I'm sure my guy knows what this is, but for my own edification...I have no idea what offset sweeps are. Can you explain it to me or show me a picture of it? Thanks.

https://absupply.net/linear-vm105-90-degree-double-sweep-3-way-t-fitting.aspx

I believe he is referring to this

tl;dr version - keep the T on the outside of the wall...

my double sinks (prior to our remodel) had the T inside the wall, so each sink had their P-trap within the cabinet below. Each of our two A/C units was tied to its own sink for primary drain.

We had a clog one time that occurred somewhere below the T, and we must not have had the sweeps like shown above. Any attempt to snake it, the snake would just come out the other sink and I could never get to the clog. Finally removed the clog with something called a 'kinetic water ram'. Only other option would have been to open up the wall and access the pipe that way.

We have since remodeled, so we no longer have a double sink.