I bought this house and in the basement is a 4 inch pipe that sits fairly level with the floor. It has a round piece of wood capping it. When it rains hard, this wood cap blows and I get a basement full of raw sewage. The neighor told me it's a cast iron pipe used for a toilet, but there is no flange and he didn't know how to plug it. I have no intentions of ever putting a toilet down there, so how do I cap this pipe so I have no more water issues?

Hi Handynotgirl:

Hmmm... could be a main drain cleanout... maybe? Have you checked the pipe to see if there are any threads on the inside of the pipe? If not, check for threads... if present then you should only need to go to a local plumbing supply house and get a universal fit lead plug or you can measure the diameter across the pipe/threads and see if they have a plug to fit that. While you are at the supply house pick up some pipe dope as well, to coat the plug threads... ;)

Otherwise, you could cap the pipe using a cast iron cap and a shielded clamp(see images). Here, you would need to have some of the cement around the pipe chipped out using a cold chisel and hammer and then you could attach the cap and tighten up the clamp. You could also install a rubber JIM CAP (see image), or a wing-nut type of expanding plug (see image)although these are not considered permanent solutions!

You could also have a plumber come out and pour a lead joint with a cast iron cap. Here, the plumber fills the pipe with sand and then installs a cast iron plug with oakum material and leads the plug in so you have a permanent seal.

There is a couple options...

Mark

What you have sounds liken a rough in for a future toilet. Mark gave you some excellent options.
Another would be to simply jam rags in the pipe to seal it off and fill the pipe with cement. Bring it to grade and smooth it out and from there you can either paint or tile the floor.
Good luck, Tom

I see a logical inconsistency here. Rain water should not be entering your sanitary sewer line. Yet, you said that you get raw sewage into your basement. Are you sure that it is sewage and not just water. Are you on a septic system. Could this pipe be a floor drain that drains to daylight?

Rain water should not be entering your sanitary sewer line. Some local codes allow rainwater runoff to tieback to the sewer. If the volume overloads the system all kind of nasty stuff will back up out of the house main.
You have several options here.
1) Cap or plug off the 4" pipe
**OR**
2) Disconnect the gutters from the sewer and disperse it in a dry well, (see image) or over the ground. Good luck, Tom