Adjust Toilet Waste Pipe Slope

[gerkear]

Ever since we purchased our house we've had a sporadic problem of our 1st floor toilet not completely flushing. This even occurs under minimal waste. I adjusted the chain and replaced the flapper but saw no results.

I recently went in the basement to inspect the toilet waste pipe which travels from the toilet roughly 5 feet to the main sewer stack. I put a 4 foot level on it only to find that the waste pipe between the toilet and stack is nearly level.

Can I adjust the level of the existing (glued) pvc to force in a slope or should I cut the pipe close to the stack and reinstall using pipe hangers to achieve a 1/4" per foot slope required? Both options would require some modifications at the toilet flange which I am aware of.

Any suggestions would be helpful. Thanks!

 

[phishfood]

To be honest, as long as the pipe does not have backfall, I doubt that is the source of the problem. I know that some codes require 1/4" per foot of fall on 3", but the code that I work under only requires 1/8" per foot, and we don't see a problem with stoppages due to not enough fall on the pipe. Over the length of the 4' level, how much fall did you have?

What brand of toilet do you have?

If you do decide to go ahead with adding some fall to the pipe, you should be alright with just working with the existing pipe, unless it actually does have backfall on it. The only caveat is that if the PVC pipe is really old, it could be brittle, and would require some caution.

 

[gerkear]

Over the length of the 4' level, how much fall did you have?

What brand of toilet do you have?

I measured a gap of approximately 1/8" - 1/4" (I was using a crappy plastic triangle) across the 4ft. So best case of 1/16" per foot.

The toilet is a Lamosa. It seems like a "smaller" model. See the attached picture.

 

[Mr_David]

I agree with phish. You don't seem to be having a stoppage problem,
but a problem with the toilet actually clearing it self 100% when flushed.
This is most likely the toilet.