A new, strange noise is coming from a slop sink that is located next to my washing machine in the basement. The washing machine exhausts into the slop sink and the slop sink drains rather well since I plunged it a few weeks ago.
In the past few days I have been occasionally hearing glunk-glunk noises from the empty slop sink. I am not in the basement much, but I do not hear the noise all the time,
What might be causing this and what might I do about it?
Update: Toilet in basement just overflowed with contents of upstairs toilets. I guess my soil pipe to the street is clogged. I should have paid more attention to the glunk-glunk noise when I heard it a few days ago.
Second Update: Just had the sewer pipe cleaned out. The crew found roots growing in it. (The sewer service company came quickly!)