"John Smith" wrote ...
| My upstairs toilet still flushes, but the water doesn't leave fast,
| so that the bowl fills up and empties slowly, and ends up less
| full (of water) than usually. It also gurgles (outside where
| the vertical drain-pipe is) halfway through.
| I have a heavy vertical iron drain-pipe outside, which has the
| bit that sticks up in the air for venting. At the bottom, there
| is a horizontal underground run for about 3 meters, at the end
| of which is a manhole where everything seems ok.
| I worry that the underground bit has collapsed, and I will not be
| able to do that myself. I also generally worry about the heavy
| iron venting pipe (in case it falls), which is right over where
| we sit outside in the summer.
| Questions:
| 1. What is likely to be wrong ?

Most likely, toothbrush/etc and accumulated 'mess' round the bend of the WC
slowing down the discharge. Get your arm round the bend and have a feel :-(

| 2. What can you do if the underground bit has collapsed ?

Dig it up and replace it.

| 3. How heavy is the iron pipe likely to be (per foot), if I want to
| try to take it down myself ?

Does it look like it's coming away from the wall? If not, leave well alone.

If the top of the vent pipe is not beyond reach (scaffold tower?) then get a
big bucket of water and chuck it down the pipe with someone else watching
the manhole. If it comes out the manhole with a whoosh then there's nothing
wrong with the main pipe and the problem is with the branch to the WC or the
WC trap.

Owain