HELP!!!! Dorm sink water coming back up through drain?

The drain is backed up somewhere, try plugging the drain and using a plunger at another near by drain such as the bath tub

The age of the sink or plumbing is totally irrelevant. Your drain is clogged with hair and the bacteria growing in the clogged drain causes that smell. It appears as though the drain has not been cleaned in a while, so build up has clogged the water from draining.

You will need to do one of two things, maybe both: Get drain cleaner or a tool to pull up the hair stuck in the drain. The tool is a long thin plastic object that has barbs, like thorns, on it. When pushed down the drain and pulled back out, the hair that is in the drain comes out. This simple tool will save you money from hiring a plumber. Follow by drain cleaner and you are good to go. Read all drain cleaning directions and follow them exactly.

I grew up in a household with siblings. We have thick curly hair. We were not allowed to brush our hair in the bathroom, only in our bedrooms. Because with a brood of kids with our hair, the sink was always getting clogged. As soon as we all stopped brushing our hair in the bathroom, no more problems with clogged sink drains!! Still, to this day, I do not brush my hair over a sink.