What Does it Mean When Black Stuff Comes From the Drain of Your Sink?

Hunker may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here.

When you see black stuff coming out of sink drains, stop using the sink until you've determined the source of the black material. Black stuff coming up through any drain in your house may be from a sewage backup, which can lead to serious damage to your home. If you drink water containing sewage, it can also result in increased risk of disease, according to the Centers for Disease Control.


Why is Black Stuff Coming Out of My Sink?

When you use your sink, you may inadvertently wash biological materials down the drain, such as hair, skin oils and soap, which grows bacteria that is black. Some of these biological materials cling to the sides of the drain body as well as the drainpipe, forming a layer of film. This biological film provides a breeding ground for bacteria, which turns the film black. Sometimes the black film comes loose, for instance, when you pour drain cleaners or other harsh substances down the drain.

There are a few reasons why black stuff may be coming out of your sink.

Video of the Day

1. Clogged Drain

Whether you have a partial or complete clog in your sink's drain, part of the clog may come loose and make its way up and out of the sink's drain. If your sink has standing water in the drain, or if you notice that the water takes longer than usual to drain out of the sink, a clog is likely the source of the black material in the drain.


Often clogs are made up of biological material. This means that bacteria breeds in the clogs and turns them black. Using a plunger or a drain auger should clear the clog out and stop more black stuff coming out of sink or black water coming out of tub drain.

2. Vent Pipe Obstruction

An obstruction in the vent pipes that connect to your sink's drain line may also lead to waste water coming up through the sink's drain. The vent pipes attach to the branch drainpipes or the pipes that several plumbing fixtures feed into.


Without proper ventilation, the waste water from one of the other plumbing fixtures can flow up the sink's drainpipe, eventually coming through the drain opening. This can also lead to dirt coming up shower drain. You must climb onto the roof to remove the clog with a garden hose and a high-pressure attachment.

3. Sewage Backup Problems

The black stuff coming through your sink's drain may be sewage backing up through all of the drainpipes in the house. Normally, backed-up sewage comes through the drains in a basement first, since this is generally the lowest part of the house. It's good to know that if your sink is in the lowest level of the house, it will be one of the first to have sewage come out of the drain.


A sewage backup may result from a problem with the sewer system that the city must fix, a full septic tank you must have emptied professionally, or a large clog in the sewer drainpipe between the house and the sewer system. A large clog must generally be removed by a plumber.



Report an Issue

screenshot of the current page

Screenshot loading...