I accidentally poured some mortar and grout down my bathroom drain when I was cleaning the remains of a bucket of mortar after tiling the kitchen. The drain was plugged up pretty bad so I tried to scrape some of it out with a wire hanger down the overflow, and that got it flowing again, but its still draining kind of slow.
It's an old house, so the drain isn't PVC, it's galvanized, or bronze, or whatever they used back in the 50's
Best Answer
You probably (and hopefully) have a large amount of sand/grout stuck in the P trap. If so your best bet would be to remove the P trap and give it a good thorough cleaning (out in the yard, with a hose).
(While the trap is off you'll be able to inspect the tailpiece and the drain line as it goes into the wall and clean those up too if necessary.)
If you can't detach your P trap you have a few options:
(My experience is most older pipes that have such a cleanout nut are so old that the thing is frozen and can't be opened without breaking the pipe, so be careful if you try this)
(In the hope that you'll wash enough of the grout further downstream that (a) your drain runs quickly again, and (b) it doesn't clog your pipes further down the line where you can't get at it.
This is really a last resort and just delays (or moves) the need for a proper fix...)