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Why is the Bathroom Sink Backing Up? (Quick Answers)

The sink is an irreparable part of your bathroom where it’s hard to imagine one without it. For a perfect ecosystem that is efficient and comfortable, you need all of its elements to work properly. Without a doubt, having your bathroom sink back up can be annoying and disturbing.

Why is the bathroom sink backing up?

There are a few ways your bathroom sink can back up. One of the main culprits is hair clogging it up. It could also be something getting stuck in the p-trap, soap scum, and last but certainly not the least, damaged pipes. Basically, it’s been obstructed and jammed and needs to be cleared out.

Since backing up happens because something is stuck in the pipes, it matters what kind of object it is so you know how to get rid of it.


Hair is one of the most common reasons for bathroom sink backing up. Since hair clumps up together when pet, pipe walls catch the clumps on their way down and starts to resist the water flow inside. 

They also start to collect anything else wanting to head down the drain, thus creating a vicious cycle that only ends up clogging things up more and more.

Something in p-trap:

The p-trap is known as the bending part of the drainpipe that’s directly beneath the sink. Since it connects the sink drain to the larger pipe system, it is vital to keep it free of obstruction. 

Smaller items tend to get caught in the p-trap such as rings, earrings, soap chunks, and sometimes even grease. If your p-trapped is clogged, you can expect to hear strange stuttering noise when water is flushing down.

Soap scum:

Chunks of soap can build up that block the water flow inside the sink. Soap scum generally happens with the magnesium and calcium present in water reacts with the chemicals of the soap.

The result is a chalky, filmy element that stays on the sides of the wall pipe and gradually builds up. This means they create significantly difficult clogs to clean since they are sticky.

Damaged pipes:

If it’s not for the above-stated reasons, it could be due to pipe damage. All kinds of pipe damage can make your bathroom sink back up. Pipes can corrode, causing the rust to build up constrict the natural flow of water. Dented pipes can do the same. 

Sometimes pipe joints just can wear out or come apart in pieces, which means they will sag and disrupt water flow. Keep your pipes securely fastened otherwise they can shift over time to become displaced and cause blockage.

Why is my bathroom sink backing up with clean water?

One of the main reasons why your bathroom sink is backing up with clean water could be because there’s an obstruction preventing it from going where it should. Things jamming up the drain hose could be the reason why as well.

You could also see if your sink is clogged and if that needs professional cleaning. If that’s not the case, it could be blockage farther down the line.

Why is my bathroom sink backing up black water?

If it’s some black element that’s coming up instead of clean or clear water, it could be bacteria that are clinging to the waste in your drain lines. This bacterium can grow and overtake if it’s not taken care of. 

Everything and anything from hair, soap film, lotions, food waste, bodily waste, and other things can accumulate and cause backing up. Black debris is a serious health issue and should not be left unattended.

How do you fix a backed-up bathroom sink?

Now that you know why your bathroom sink is backed up, let’s discuss how you can fix it and be on your merry way. 

Cleaning the stopper:

The sink stopper is at the mouth of the drain and the metal tail goes into the pipe. This position makes it catch hair and other debris like material like soap and stuff, which will ball up and cause blockage.

For modern sinks, cleaning the stopper is easy since all you have to do is unscrew it. But for older models, you have to remove the tether that holds it in place and reattach when done.  

Get rid of the sludge:

The sludge is the slimy coat that’s inside the sink’s drainpipe. If it accumulates it narrows the opening which slows the drainage.

To get rid of it, use a half cup of baking soda and a half cup of white vinegar- this combination will react and break up the small clogs. You should block the drain with a small rag so it doesn’t get out of the drain.

After 15 minutes pour boiling water down the drain and run hot water for a few minutes so the melted slime is flushed out.

Purge the debris:

Another thing you can do is get rid of the accumulated debris with a drain cleaning tool, a small hair clog tool. 

Remove the stopper, get the plastic line into the drain and just wiggle it around and see what comes up. Continue until there’s nothing coming up.

If previously mentioned methods fail, call a professional and let them deal with it. It is better to be safe than sorry in cases like these.

What to do when water is backing up?

If you see the water is backing up in your bathroom facilities, there are a few things you should do as soon as possible.

First, you should diagnose and clear up the blockages. See what’s making it back up and work on it immediately.

To prevent accidents from happening, take some safety precautions such as turning the power off if there’s standing water present, wearing rubber boots and safety glasses, and a mask.

You should also document what’s happening so you can be of more help to professionals if this continues to occur. 

Why is my bathroom sink not draining?

If you see your bathroom sink isn’t draining properly, there could be a few reasons why it’s happening.

Usually, these problems happen because of hair or gummy soap remains that got caught and are clogging up the drain. It could also be the pop-up that’s used to stop up the sink is collecting sludge and gunk.

The build-up gradually collects itself over time, causing the pipe to narrow and stopping the proper drainage.

How do you unclog a bathroom sink with standing water?

Bathroom sinks clogging up is annoying as is, but if they have standing water as well, it just becomes downright frustrating. Here are a few tips that may help.

  • Take safety precautions before doing anything else. Wear protective gear to keep yourself safe.
  • Use a bucket or cup to remove as much of the water you can before attempting to unclog the drain.
  • Remove any items you can find in the jammed-up drain.
  • Use the baking soda and vinegar combo to dissolve grease and oil, wait 15 or so minutes and wash it down with hot water.
  • Use a plunger and get it all sucked out.
  • Finally, run water into the drain to see if it’s gone.

Do bathroom sinks come in standard sizes? 

There is no size for a bathroom sink that is the industry standard. Usually, they are about 16 to 20 inches in diameter when bowls. When they are rectangular, you can expect them to be 19 to 24 inches wide and 16 to 23 inches in length. Depth-wise, they are generally 5 to 8 inches.

Final Thoughts:

There could be various reasons why the sink is clogged. One of the most common culprits is an obstruction in the pipe in form of clogs, jammed-up objects as well as the build-up of different materials such as hair, wastes of any kind. Damage to the pipes can be another reason for weak water flow.