The possible reason is clogging of the pipe that leads to dry p trap.
My bathroom sink smells like sewer.
While it may smell dangerous the sewer smell usually consists of problem that you can fix yourself.
What causes a sewer odor in the bathroom.
It is always a sewage like odor or rotten egg smell.
A sewer odor that emits from the bathroom sink drain can cause you to panic.
Sometimes it happens that the sewer smell in the bathroom comes from the sink.
Remember all your water waste eventually drains to the same place so the runoff from your bathroom sink will be sharing a pipe with sewage down the line.
Sewer odor in bathrooms has several different causes.
Sewer smells in your bathroom can result from a few different issues so you ll need to spend a bit of time in the room to sniff out the source.
The strong smell can quickly fill your bathroom with an unpleasant odor.
If the p trap is blocked or dry it would cause a sewage smell to emanate from the sink.
It blocks sewer gases trying to travel inside your house from the exterior systems.
When the vents are blocked flushing a toilet can create sufficient vacuum to suck water out of the trap and allow sewer gases into your home.
Bathroom sink drain has all the organic matter that flows down with the water.
Bathroom sink smells like sewer.
Like many others your sink probably has a hole at the top that allows fast drainage when the sink is full of water.
If the odor emanating from your bathroom sink smells strongly of sewage then sewage may be the actual culprit.
The most common reasons are a backed up sewer cracked or rotted pipes that leak clogged drains pipe connections are too loose the vent pipe is backed up or too short there is an old wax ring or a dry trap.
There is soap hair and used toothpaste spits.
According to research the bathroom drain is the primary reason why bathroom sink smells like sewer.
A rancid odor coming from your sink drain may just be coming from debris in the p trap but if it smells like a sewer it probably means venting problems in your drain system.