I am finishing my basement, which was roughed in by the builder, but I need to move the toilet, since I lost 8" of wall framing in front of the main sewer line, the vanity would be stupidly narrow, to allow the necessary space to the center line of the toilet.

I've already excavated and figured out how much space I have to work with. Originally I was going to add two 45s, but that only gained me 5" lateral movement, and was insanely tight.

My gut says working with 4" pipe, for a toilet, going mostly vertical, I am unlikely to run into any real problems unless I run pipe uphill. Regardless, I am in a town that requires permits and inspections, so I don't want to risk wasting my time.

The first question is, is there a problem using bends above a 4" x 3" closet bend? If that is off limits, then everything else is moot.

I know code says I can't use a sanitary/short elbow to go from vertical to horizontal, but I am not sure if I could get away with it in this case, since its essentially making and "S" and immediately going vertical again. I figure if I use a long sweep for the vertical->horizontal transition, that is okay, but it is roughly 1 1/16" higher vertically to do that.

I have drawn a diagram of:

A: How things were built. B: Using 2x sanitary elbows to move things over. C: Using sanitary elbow + long sweep

Proposed plumbing solutions

All pipe is PVC Schedule 40 DWV

Would option B work (I may also use more length than the bare minimum between the two bends, that may be tricky to slope with such a short piece), or should I play it safe and go for C?

And for what its worth, it runs down a 3" pipe into a line that goes to a sewage basin. The vent is about 3-4' away from the toilet line, and it is a 2" vent shared with the sink and shower. The sewage pump also has its own vent. Right now I am 21" away from the back wall, since I moved that back as well, so I am going to be moving things both sideways and backwards.

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  • I would use an offset toilet flange to give the extra room going to 3” immediately it has been a few years but I think the offset flanges move over 2-3” this allows for 3” sweeps that are shorter than 4” and not having the nightmare of plumbing of B & C and I think A will have a gurgling or worse gulg glug noise because of the restriction so close. I am not a plumber but have built and remodeled hundreds of homes and don’t think B or C would meet code. – Ed Beal May 29 at 21:01
  • I was reviewing the 2018 Plumbing Code that is applicable, table 706.3 which covers fittings for change in direction, has a new point d I hadn't seen before while researching this (I saw stuff with points a,b,c). It states the the closet bend can only be used if its centerline is no more than 12 inches below the flange. The pipe length I would be adding will most definitely break that rule, it was already 15" below the concrete, but this rule didn't exist in 2014 when the house was built. Hope the inspector isn't up to date on the latest code. – d3vd May 30 at 13:41

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