Moving a sink and water lines

Hello. I am moving my sink and water lines from one wall of my Kitchen to a peninsula 12ft across the room. I have cut my concrete about 18in wide from the original wall location to the new peninsula location. The original location was vented through the roof. I plan on tapping the drain and hot and cold from that original location. I am running all three lines together through the trench I have dug. Do I need to have an incline/decline in my "extension" drain pipe as it goes back to the original? I will "T" it into the original and leave the existing roof vent. Will I need a Studor valve at the new sink location? Anything else I am missing? Thanks for the advise!

Did you seriously just ask if you needed to slope a drain?

I think you need to do a LOT more reading before even attempting this.

If you don't slope it at least 3" over the 12' run, you should invest in a good quality drain snake machine...you will need it often.

If you are joining horizontal to horizontal, then a tee is not the correct fitting.

You need to get a plumbing permit. When you get the plumbing permit talk to the inspector about how he wants the drain installed/vented. You will need slope and 1/4" per foot is the norm.

Islands can be done a couple ways.

Reminds of a dumba@@ inspector that couldn't or wouldn't say "Island". He would say....."You need an IS-Land vent" I kept asking WTH is a IS land vent.....I think it made him made. LOL

Unless in Miami gravity is reversed so that water will run up hill, you will need to slope the drain.