It's up to the inspector; they like to see 1/4" per foot on 3" and 4"
On 4", they sometimes let you get by with 1/8" per foot.
The sections with more slope are not an issue.
I have dug my basement deeper and will have a toilet connecting to a 4” pvc sewer line under the slab that runs 45’ to an ejector pit. I know the current rough-in does not meet code but, assuming it passes inspection, I am wondering if it is good enough as my contractor claims. On average the slope of the line is almost precisely ¼” per foot, but the slope varies. The first 10’ is 0.17” per foot, the next 6’ that is between two 45 degree turns is 0.41” per foot, the next 24’ is 0.27” per foot, and the last 5’ into the pit that begins with a 25 degree turn is 0.11” per foot.
A drawing is attached.
Should I insist that it be redone?
Thanks Terry. My objective is a trouble-free sewer line, not necessarily inspection approval. In your experience, do you think the system as currently designed is likely to be trouble-free?
My concern is that there can always be some movement, particularly if the groundwater level ever rises close to the level of the excavation. If the pipe is bedded in well it will probably be fine, but I would feel better knowing there is more pitch than required rather than less.
There must have been a good reason for not placing the basin close to the bath to avoid all the underfloor piping.