I want to build a bathroom in my garage on top of the cement slab. I can elevate the toilet so no problem there. However, where the sewer line exits the garage, I have only a one foot space in a planter area to get under a walkway. This means a sudden drop of 5 inches in a one foot space. Would two 90 degree bends be better than two 45's to make that 5 inch drop? I am thinking that, this would be the best way to keep the water from washing away from the solid waste.

I would go with 45's. They will allow easier flow than 90's. If you need to use 90's make sure to use a long sweep elbow.

As suggested in above post, I would also use 2 - 45 degree bends to negotiate the drop. That assures better flow. If you are short on space, try to use Street 45s to save couple of inches. If no slack to make the final connection, use Fernco Flex Seal coupling.

Back to you / Milo

Okay. Thanks for the tips. After having thought about it some more, I realized I was going to have to put in a sanitary T so that I could also go straight up for my main sewer stack. Of course that in turn means the sewage will drop straight down. So I guess that calls for a single long sweep 90 elbow. Does that sound about right?

Why not a sanitary Y and a 45 degree sweep.

Why not a sanitary Y and a 45 degree sweep.

Sounds good but, would that require another 45 for the sewer stack going up as well?

I guess I thought you were going from a horizontal line into the stack.

If this is going to be a toilet, lavatory and shower I can see you platforming most of the garage. Why not break up the slab and end up with a professional looking job. You have the pitch and fall tom make it work. Here's a typical bath layout. Good luck, Tom

I guess I thought you were going from a horizontal line into the stack.Yes. I guess I just thought I needed another 45 to go straight up with my stack which would be 90 degrees to the line coming out of the wall.

If this is gonna be a toilet, lavatory and shower I can see you platforming most of the garage. Why not break up the slab and end up with a professional looking job. You have the pitch and fall tom make it work. Here's a typical bath layout. Good luck, TomThanks Tom. That drawing is basically what I had planned except my shower and vanity lines will be hidden by the vanity cabinet and broom closet. Since the toilet will be elevated, those lines will be hidden as well. Didn't want to break up the concrete if that could be avoided. Here's the kicker. I plan to squeeze all this in below the garage door as it opens. I measured the height of the garage door and I have 81 inches when it lifts in an opened state (have to make a pocket for the armature swing), so I calculated this could be done if I make my bathroom ceiling height only 6' 8" instead of 8 feet. A custom job to be sure, but I think doable.