I have a question about a leak in a sewage line. A cast iron pipe collects waste from a single toilet and runs down 5-6 ft vertically to the basement where it fuses with the house main sewage pipe through an L-shaped cast iron segment of the same diameter (2 ft vertical, 90 degree turn, then 2 ft horizontal). The rubber coupling connecting the vertical part of the L-shaped segment to the toilet pipe suddenly started gushing water after each toilet flush. Nothing else causes this leak, just that toilet; that is, the rest of the sewage runs okay. The toilet flushes normally, no standing water. I suspect that the horizontal part of the L-shaped pipe got dead clogged. Do I have to remove the toilet to clear the clog with an auger or applying some sort of chemicals would be possible? Why would this 12 in. pipe get suddenly clogged? Thanks in advance!

By "L" shaped pipe do you mean closet bend? I would replace that rubber clamp with a Fernco Metal Shielded Coupling ASOP.

. Do I have to remove the toilet to clear the clog If it's in the closet bend the answer is yes, The only way to clear the clog is to snake it out. Good luck, Tom,

By "L" shaped pipe do you mean closet bend?

Thanks. Yes, what I called L-shaped thing is a cast iron closet bend. Does coupling have to be 100% air and water tight? I guess replacing coupling means the closet bend has to be taken off and cleaned anyway.

Does coupling have to be 100% air and water tight? Absolutely!
EVERY connection must be 100% air and water tight.

I guess replacing coupling means the closet bend has to be taken off and cleaned anyway. Yep! Good luck, Tom

Thanks. I am not sure now what the best approach is here. Clearing the clog is one thing -- this I can do after removing the toilet. Sealing leaking connection between two cast iron pipes is another project. Red arrow on the photo point to where the water gushes from when toilets are flushed. Flushing toilets attached to pipes 1 and 2 causes the leak. There is no rubber coupling at the leak site as I have thought before. Stack 3 drains well. The segment 4 is where, I think, the clog is that backs up the water coming from 1 and 2 up the leak site. I was wondering about how to seal this leak. I am suspecting that this leaking connection has never been water tight, but it wasn't a problem as long as there was no clog. Therefore, there is a chance that when I clear the clog the leak stops. Is it possible to take these two segments (between 1 and 4) off for cleaning and then reassemble them with new sealing without professional equipment? Any suggestion would be greatly appreciated.

Check the hub and fitting very closey in the leaking area for any small cracks. I don't think you will find one, as your cast iron looks in pretty good shape. Here, you would only need to re-caulk the fitting. Basically, all you need for this is the correct caulking irons and a hammer. Tom has much more experience with this than I, so I hope he pops in with his advice. Heck, most of the pros here have more experience with lead and okum joints that I do. I was brought up in the good old PVC days, and only use lead when replacing old closet flanges, and maybe every once in a while for creative plumbing, lol.

Hi Harum

That is extra heavy (XH) cast iron fittings, so like Mygirlsdad77 said, check for cracks, but most likely the fitting is in good shape and should only need to have the lead recaulked in.

Also, like you said, when you unclog this the leak will probably stop, BUT you should still caulk the lead back in to stop any sewer gasses from escaping, OK?

Purchase an inside/outside caulking iron at a local plumbing supply store and then simply peen the lead back into the joint... be gentle, but use the irons to spread the lead to refill the joint. You could also use some silicone caulking to fill the leak, but as a plumber, I won't admit I suggested that, OK... :)

Good luck!

Mark

Removed the toilet bowl and pulled out from down below whatever could with a 1/2 in. auger rotating it manually. Not much came out but it did the job. Hope it will last for a little while. Thanks for all the help!

And we thank you for the update. If we can ever help in the future just ask. Good luck, Tom