Q:

What is the maximum number of load bearing studs in a row that can be notched?

I'm trying to install a new utility sink and washer hookup in my garage and am trying to plan how I'm going to run the copper supply lines. 
The most direct path I can think of is to notch probably 5 or so studs of an exterior wall to reach the existing drain I'm going to use for the sink.
I know that I can't notch a load bearing 2x4 more than 7/8" but I can't find any guidelines as to how many studs in a row I can safely notch. Is this a question for an engineer? I don't want to go notch crazy but I think 5 or so in a row should be ok? I'm also planning on putting stud shoes on the studs i do notch. 

A:

There is no specific limit on the number of sequential studs, as the 7/8" limit is intended to reduce the potential stresses, however, given the choice, I would rather drill than notch:
2308.9.11 Bored holes. A hole not greater in diameter than 40 percent of the stud width is permitted to be bored in any wood stud. [...]
and
In no case shall the edge of the bored hole be nearer than 5/8 inch (15.9 mm) to the edge of the stud.
So 40% of 3.5 in gives you ~1 3/8" to use, often much more than you need for supply lines.
My concern though, is that you're thinking of notching for a waste line, and notching 7/8" to add a 1 1/2 or 2" drain line is... I'll just say that I'm with @JohnSmith in that I wouldn't bother, but then I don't know your specific situation.

