I just noticed that in my basement, a section of my soilpipe has
rusted through, seeping brown liquid at times. This section looks
like a Y and is made of cast iron, I think. Am I doomed to remove it
and replace it, or can this material be repaired somehow?

KLS wrote:

I just noticed that in my basement, a section of my soilpipe has
rusted through, seeping brown liquid at times. This section looks
like a Y and is made of cast iron, I think. Am I doomed to remove it
and replace it, or can this material be repaired somehow?

There *is* a product called Soil Pipe Cement, which is useful
as a temp patch on some leaks.
It would be very unusual for a WYE fitting to rust through;
it is a very heavy casting. It might have developed a split
from being too tightly calked at installation.

I would use a wire brush to clean it up and a hair dryer to
make the metal dry before applying any patch.

Bet you have to cut this thing out and replace before too long.
Thankfully, it's not *inside* a wall!

Jim