Can you use a carpenter level as a plumbing level for drain pitch slope?

[Mark249]

I'm running 3 inch pvc pipe 20 foot horizontally from my toilet to my septic drain. From the beginning to end of my first 10 foot length I should have a 2 1/2 inch drop from my floor which will give me a 1/4" pitch, I add a coupling and another 10 foot length and I should have a 5 inch drop at the end of my 20 foot right? I have a 4' digital carpenters level which has a angle mode I can set for 1/8, 1/4, 3/8, 1/2, etc, right now my pipe is temporally hanging with a drop of 5 inches from beginning to end at 20 feet which should be correct for a 1/4 inch pitch. I put my carpenter level on and it's only showing an 1/8 inch pitch, I'm not sure if I should go with my 5 inch drop at the end of 20 feet or go by the level, is a carpenters level different from a plumbers level for showing pitch?

 

[wwhitney]

The floor you are measuring against may not be level.

A simple thing to do is take a 2' level (or longer) and cut a piece of 1/2" thick material (or thicker if the level is longer) and use it as a shim at one end of the level.

Cheers, Wayne

 

[Sponsor]

 

[Terry]

I have small levels and also a four foot level. The longer one is nice for marking studs and installing shower pans and bathtubs.
Wayne's suggestion of a shim on one side is a good one.

 

[Mark249]

I never did put the level on the bottom of the floor in the basement to see if it was level or not, it's a new built so I assumed it was, I'll check it to see if it's off. As long as I can use a 4 foot carpenter lever I'd rather use that anyways, it shows me a lit digital readout which is easy to see between my joist, I'll just keep sliding the level down my pipe and adjust my hangers til it shows a 1/4 inch pitch all the way to the end. I'd rather ask than have to little or to much pitch on this pipe seeing it's a toilet drain line, thanks for all the help....

 

[Jeff H Young]

a 4 foot carpenters level is good. you want 1/4 inch per foot more than one way to get this a shim might help.
If you had 5 1/2 or 6 inches in 20 foot it wouldnt make it a bad job. my code any spot along the entire length must have a bare minimum of 1/4 inch per fall and ispectors can nit pick so why would a little more hurt? yours might allow only 1/8th but I dont go there even on 4 inch unless I must

 

[Mark249]

I put the level on the bottom of my floor and it's right on the money, showing level. I adjusted all my hangers and ran the pipe with my digital level, it was showing 1/4 inch all the way to the end, I also took a measurement for my drop at the end and I'm still off, level says 1/4 inch all the way down to the end of my first 10 foot piece, I started at 7 3/4 inches at the beginning and I should have a 2 1/2 inch drop at the end of 10 feet, I end up with 11 1/2 inch drop, can't figure out where problem is. Sent a couple pics so you can see my piping, maybe it's just me but for 10 feet that looks like a lot of pitch. Tomorrow I'm gonna try that shim trick and I'll let you know what I come up with...

 

[Mark249]

Not sure if this helps or not..

 

[Jeff H Young]

did you check level by turning it around 180 degrees bubble still in center?

 

[Mark249]

I re-adjusted my pipe hangers again and put it at a 5 inch drop for 20 foot. Purchased a 10 inch plumbing level that has the pitch marks on the bubble site and with the 5 inch drop it shows me at a 1/4 inch per foot. I guess that digital carpenters level may be good to show angles but not accurate enough for pitch. Learned something new today, use the right tool for the right job, thanks for all help and all the great tips....