I’ve put a temporary patch on the drain pipe, so that the kids can use their bathroom. A piece of rubber and a hose clamp will seal the leak until I have time to do the heavy lifting (and until I can invite a friend over to help :-)…

Update from 2025: we replaced the patch - and the rest of the damaged pipe - in November 2024. So my “patch” lasted 20 years!

We have a saying at work about temporary fixes becoming permanent…