Hello everyone,
Quick question: What is the diameter of a sump pump discharge pipe? I had this as a test question and the internet gives me three answers. 1 1/4", 1 1/2", or 2". The internet gives me all three answers and all three answers were on the test.
I have seen all sizes installed. Size will be determined by pump installed. I would say the most common size I see is 1.5".
Yeah, that’s kind of a crappy question. The size depends on the pump. I agree with Dennis that most common is 1.5" but I’ve seen some that accept garden hose.
Thanks guys I changed my answer from 1 1/2” to 1 1/4” and missed passing by 1 point! 
I also found two other questions that I got right and changed my answers. I will definitely pass it next month
What was the EXACT wording of the question?
The Minnesota minimum discharge size is 1-1/4". I would assume all states have a similar requirement.
I’m in Washington state. I tried to be as exact as possible with my wording
The answer is 1.5”.
From the Internachi Plumbing Course…
(Poor verbiage, but the course states 1-1/4 inch minimum pipe diameter).
Thanks Jeffrey! Everyone’s help is much appreciated
But then we get caught in the whole code v. manufacturer’s instructions circle… Code book says manufacturer’s instructions must be followed, manufacturer’s instructions say code book must be followed. So, where does that leave us with the crappy cheap pumps that discharge through a garden hose?
IMO, this is the exact type of question that has no place on an HI exam. The inspector that “learns” this info about minimum pipe diameter will get out into the field and die on a hill trying to tow the line of what he has learned and end up just pissing a bunch of people off and looking bad.
The course does not say 1 1/4”. It says minimum 1-1/4”. The OP did not ask what the minimum sump pump discharge pipe was either.
I’ve never encountered a sump pump that is threaded for a 1-1/4” male adapter.
Bingo…
As usual, you do not post the entire post. The OP was not looking for minimum sump pump discharge pipe size. Amazing how angry you get when you’re pulled out into the light.
The course described minimum size pipe discharge. Not the same thing. The industry standard for sump pumps is 1.5 inch discharge.
As usual, your comprehension is sorely lacking!
The OP asked what the size was to determine the correct answer regarding the InterNachi Test.
The InterNachi Course states a MINIMUM of 1-1/4", thus the answer of 1-1/4" would likely be the correct answer to the InterNachi test.
“Standards” are NOT requirements!
As posted, my state, Minnesota, REQUIRES a minimum of 1-1/4" and/or the size of the installed pump.
As posted, the OP’s state, Washington, REQUIRES a minimum of the installed pump size.
Just because YOU have never seen one, doesn’t mean they don’t exist.
GOOGLE it!
Who’s angry?
You’re the one getting all “butthurt” whenever anyone, (particularly me), points our your false information!
Perhaps you need a ‘double dose’…
I’ve never seen a foundation like that, it gives “stone foundation” a whole new meaning. LOL
Yes, and I see a lot of old stone foundations around here. 
I seen one a while back, it had a central vac hose hooked up to it.
