Toilet Drain Line Slopes the Wrong Way

Hi everybody,

I'm re-locating the toliet in my master bathroom. I cut through my concrete floor and cut my exisiting 3" horizontal cast iron drain line. I left a 12" stub on the cast iron to connect new PVC plumbing.

My problem is that the 12" cast iron stub doesn't slope toward the main stack..apparently it never did. It slopes away from the main drain stack at about 1/2" per foot. I can only assume the rest of my plumbing beyond the hub where the cast iron stub connects to the main drain stack is sloping properly!

How do I properly extend the toliet drain line another 6ft if the cast iron stub slopes the wrong way?

My options are...
1. Connect straight to the end of the cast iron stub and don't worry about the wrong slope

2. Correct the angle of the slope by installing a 22 degree PVC elbow close to the end of the cast iron stub

3. Remove more concrete floor and remove part the cast iron coupling hub at the main drain stack.

Which one?


Thanks,

Mike in Florida

I'd probably remove the pipe from the hub and then use a fernco donut and run new pvc from there. Are you sure you have enough depth to get the proper slope to the new location?

How do you separate a cast iron pipe from a cast iron hub?

And yes, I have enough depth to get the proper slope to the new location.

The pipe is attached with a poured lead seal along with oiled hemp (oakum) that was tamped into the joint first. You make swiss cheese of the lead, pry it out, the you can then remove the pipe, clean out the oakum (wire brush may be necessary). Then you can use a donut. Most of the time, the hub is a standard size and you can get the donut in a big box store...sometimes it is not. They come in numerous sizes, the stores only carry one - a plumbing supply probably at least several, the manufacturer lots. The inside is the same, but the outside needs to also fit tight into the hub to make the seal. basically, it's a friction/compression fit. It usually takes some dishwashing soap to help lubricate things so you can push it all together. Once you have a stub of pvc in there, you can add whatever angles to give you the proper slope. There is a little bit of leaway while maintaing a good seal, but basically it needs to come straight out of the hub.

The pros can guide you further. I've removed a few. If you have decent access, it doesn't take all that much time, maybe 10-15-minutes. If you don't, it could be much longer.

Did it! Thanks Jim! I really appreciate your help...

Mike