How does the drainage system work, exactly?

Question

I came home and my sink is clogged. It's a blackish grey color, so I start with a snake. Doesn't work. I start emptying the sink in to a bucket so that I can poor some DrainO down the drain and right when I've emptied the water, the neighbor flushes and my sink fills right back up.

I don't know how drainage systems work, but was that toilet water I was draining from my sink? Or please tell me that there's two totally different drainage systems (please).

Thanks

Answer 1

If your sink fills back up after your neighbor flushes there toilet - than The matter in your sink is sewage - sorry.
There is an obstruction downline which prohibits there sewage from flowing down the drainage line. Unfortunately, your sink offers the path for least resistence for the sewage water to go. You may need a "backwater control valve" placed in the drain line to keep their sewage from backflowing into your residence - Id have the mainline unclogged with a sewer tape or augar which may open up the drain line. Wish I had better news - Good luck.

Answer 2

Sorry, only one drainage system for all waste water. The line from your sink goes into the wall into a tee that goes up, for the vent, and down, for the drain. This pipe ties into a main drain (larger line). There is a clog in the main drain that needs to be cleared. Depending on where the clog is, it could also come up in your tub.