As a follow up to this question, I live in CA and I am putting in a bathroom (sink, toilet and shower) installed on a slab. I heard that the sewer line must start at 18" below grade nad start it's run to the main sewer. The only way i can make this (1/4" per foot) is to start with the line at only 10"below the shower (the last drain before it goes out). Since there is no chance of freezing is that OK or do i need to go 18"

Hey Jim and welcome to The Plumbing Page on AMHD.
You piggybacked on a 5 year old dead thread so I gave you one of your own. Before you post look in the upper left hand corner for the date. We rough in different on a remodel, Milo is a Cal plumber and knows the code out there. My my code you would be fine but wait till Milo checks in to be sure. Regards, Tom