I am adding another bathroom to our 3 bath house, we have a 3" sewer main. Is that adequate to drain the additional bathroom?

In most places I believe that a 3" drain line is the minimum allowed for a bathtub and 2 1/2" for a stool or sink. You can check your local code or call the city planning and permits office.

Amsteube... your information is inaccurate... ;) Maine, Mass. Florida, California all have same minimium size requirements... That is, 3" minimum for a toilet, 1.5" minimum for sink and tub, 2" for shower. If piped underground then 2" is minimum size allowed underground so sink and tub kick up to 2" pipe. It is also very uncommon to use 2.5" pipe for anything. And not to bust yer Balls here (I swear), but the question wasn't even about minimum pipe sizes for fixtures... it was about sizing of the main sewer line to accommodate additional bathroom... Just FYI...ok?

Jim... you said your 3 bathroom house... does this include the new bathroom or not? If not (making this a 4 bath house), then the 3" will not be the appropriate size. All codes that I know of will not allow more than 3 toilets on any 3" drain pipe. If your main sewer is 3" then, by code, it will need to be increased to 4" to add the 4th toilet...

Let me know more here...

MARK

Size of sewer lines is given by number of plumbing fixtures connected to it. Rule of thumb is: 2 bathrooms = 3" pipe. More than 2 bathooms ( or 2 toilets ) = 4" pipe. By Code, you will have to upgrade portion of your existing sewer to accommodate the new bath.

Jim... in Maine, you can have up to 3 bathrooms on a 3" drain. Milo's from California and his codes differ from our area.

Answer all questions I asked earlier... ok?

Thanks...

MARK