Why Does My Bathroom Sink Smell? [And What To Do About It]

There aren't many worse smells than the odor of sewage or rotten eggs in your bathroom. Often, these unpleasant odors start in your sink's plumbing.

So, why might your bathroom sink be giving off bad smells, and how do you fix the problem? We've done the research, and we have the answers for you!

The following are the most likely reasons why your bathroom sink smells badly—with a quick description of how to fix each one:

  • A clog in the drainpipe: pour drain cleaner in and use a drain scraper.
  • P-trap is dry: pour a quart of water down the drain.
  • Leaky P-trap: replace washers or P-trap.
  • Faulty vent pipe: must be fixed by a plumber.
  • Contaminated water in water heater: replace the anodized rod. 
  • Bacteria inside the faucet: remove the aerator and clean the faucet with vinegar and baking soda.
  • Drain system contaminated: flush with baking soda and vinegar and scrub with a drain cleaning brush.

In the remainder of this article, we'll describe each of these issues in detail and provide step-by-step instructions for fixing them.

We will also explain how to maintain your bathroom sink drain pipes so that you never have to worry about smelly drains again. Keep reading to learn more!

Interior of a modern bathroom with gorgeous tiles bathroom with a white ceramic sink, Why Does My Bathroom Sink Smell? [And What To Do About It]

Smelly Bathroom Sinks And How To Fix Them

There are two reasons your bathroom sink might be emitting foul odors: sewer gases are coming up through the drain pipes, or bacteria in the drains are creating a foul odor. We'll examine each of these possibilities in turn.

Before you begin working on your bathroom sink, recall these two important tips:

  1. Never use bleach with another cleaning agent: this could cause a dangerous chemical reaction, releasing harmful gases into your bathroom.
  2. If your home is hooked up to a septic system rather than a city sewer, do not use bleach for cleaning. Bleach will kill the good bacteria that break down waste in your septic tank.

Why Does My Sink Smell Like Sewage?

If your bathroom sink smells like sewage, it is because sewer gases are rising through the sink's drainpipe. This situation can be caused by any of several reasons: a clog in the drainpipe, a dry P-trap, leaky pipes, or a faulty vent pipe.


If you trace a sewage odor back to your bathroom sink, first check for a clog in the drainpipe.

Hair, skin, soap residue, and other materials build-up in the bends of the pipe. Air pockets in these clogs allow sewer gases to rise through the drainpipe.

The best way to determine whether your bathroom sink's drainpipe is clogged is to run water into the sink and see whether it flows down the drain at normal speed. If the water in the drain backs up into the sink, you probably have a clog.

First, attempt to unclog the drain using a plunger:

  1. Run water into the sink until the drainpipe is full and a small amount of water covers the bottom of the sink.
  2. Place the open end of the plunger at the mouth of the drain, making sure that the entire drain mouth is covered.
  3. Grasp the handle of the plunger and pump it down and up several times. The rubber plunger bulb will depress and unfold with each pump.

If several attempts to clear the drain with a plunger are unsuccessful, you may have to use a chemical drain clog dissolver like the one shown below.

  1. Following the directions on the bottle, carefully pour drain cleaner into the drain.
  2. Allow it to sit for 15 to 30 minutes.
  3. Flush the drain with hot water.
  4. If your sink still drains slowly, insert the plastic scraping tool down the drain.
  5. Carefully oscillate and twist the scraping tool to gather any solid matter in the drain.
  6. Slowly pull the scraping tool out of the drain. Take care not to splash any of the drain cleaner onto your skin or eyes.
  7. Run hot water down the drain again.
  8. Repeat steps 4-7 until the drain runs freely again.

Click here for drain cleaner on Amazon.

Dry P-Trap

If there is no clog, your sink may have a dry P-trap. The P-trap is the curved piece of drainpipe below the sink.

Its purpose is to hold water, forming a protective barrier that prevents sewer gases from rising back up and out the drain's mouth. If the P-trap is dry or nearly dry, gases can escape up the drain.

Especially in sinks that haven't been used for a while—guest bathrooms, for example—the water in the P-trap may have simply evaporated. This is an easy problem to fix:

  1. Pour a quart of water into the drain.
  2. Leave the room for 15 to 30 minutes.
  3. Return to the bathroom: if the smell is gone, you've solved your problem! If there is still a sewer odor, try the next suggestion below.

Leak In Sink Plumbing

A leak in the drainpipe assembly of your sink may also cause the P-trap to dry out. This is probably a job for a plumber, but you might decide to fix it yourself.

  1. Under the sink, locate the two joints where the P-trap connects to the other drainpipe sections.
  2. Set a bucket under the P-trap to catch any water that may gush out.
  3. Unscrew the nuts at the two joints between the P-trap and the other sections of the drainpipe.
  4. Pull the P-trap down and away from the drainpipe.
  5. Examine the washers between the ends of the P-trap and the ends of the other sections of the drainpipe. If the washers are corroded, replace them and re-install the P-trap.
  6. Examine the P-trap itself for cracks or holes. Replace the P-trap if it is defective.

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Click here for bathroom sink p-trap kit on Amazon.

Faulty Vent Pipes

If you've tried all of the remedies listed above and your sink is still emitting a sewage smell, the problem may be a leak, clog, or other problem with the vent pipe that carries sewer gases out through the roof.

This is not something you can fix on your own: it's time to call a plumber.

Why Does My Sink Smell Like Rotten Eggs?

If your bathroom sink smells like rotten eggs, bacteria have built up in your water heater, drainpipes, or faucets.

These bacteria feed on corroded anodized rods in water heaters and on the hair, skin cells, and soap residue built up in the water system.

They then release hydrogen sulfide gas, which contaminates the water in your system and smells of rotten eggs.

To determine whether the rotten-egg smell comes from your water supply or your drains, fill a glass with cold water from your faucet and another with hot water.

Take them both outside and smell them. If they both smell normal, the problem is in your drains. If only the hot water smells bad, your water heater is probably contaminated. On the other hand, if both glasses smell bad, your faucet is likely contaminated.

Water Heater Contaminated

If the odor is coming from your hot water, replace the anodized rod in your water heater.

This rod aims to protect the steel interior of the water heater from corrosion: corrosive elements in the water attack the rod rather than the steel.

However, as the anodized rod breaks down, it imparts a foul odor to the water in the heater. Follow these steps to replace the anodized rod:

  1. Turn off power to the water heater.
  2. Close off the inflow valve, so no more water comes into the heater.
  3. Locate the anodized rod on top of the heater element.
  4. Gently loosen and remove the rod. Be careful -- it may be hot!
  5. Install a new anodized rod.
  6. Turn the power back on, open the inflow valve, and refill the water heater.

Click here for corrosion-protective water heater rod on Amazon.

Bacteria In Faucets

If the water from both faucets smells bad, or if the anodized rod in your water heater isn't the problem, you may have bacterial contamination in one or both faucets. Follow these steps to sanitize your faucets:

  1. In a glass bowl, combine 1/2 cup baking soda with 1 cup vinegar.
  2. Unscrew and remove the aerator from the tip of the faucet; place it in the vinegar solution.
  3. Dip a long-handled drain cleaning brush into the vinegar solution and use it to scrub the inside of the faucet thoroughly.
  4. Scrub the aerator with the brush, then screw it back into place.
  5. Open the faucet and run the water until it comes out clean.

Click here for drain cleaning brush kit on Amazon.

Drain System Contaminated

Hair, skin, soap scum, and other contaminants accumulate in the drain of your bathroom sink.

Cleaning the drain with a combination of baking soda and vinegar can remove the buildup and the bacteria that feed on it. There are three distinct parts of the drainage system; you clean each in a slightly different way.

  1. To clean the main drainpipe, pour the vinegar and baking soda mixture into the drain. Let it sit for 15 minutes while scrubbing the interior of the drainpipe with a drain cleaning brush. Flush the pipe with hot water.
  2. The tailpiece—the pipe leading from the bottom of the sink to the P-trap—often dries out because it is constantly exposed to air. Unscrew it from the sink and P-trap, scrub its interior thoroughly with the vinegar/baking soda mixture, and flush it with hot water before re-attaching it.
  3. The overflow drain is accessed via a small hole near the top of the sink. Use a turkey baster to squirt vinegar/baking soda mixture into the drain; then scrub it thoroughly with the drain cleaning brush. Repeat multiple times, then flush the overflow drain with hot water.

Click here for baking soda on Amazon.

Is A Sulfur Smell Dangerous?

Hydrogen sulfide, ammonia, and carbon dioxide gases are all components of that awful sewage smell in your bathroom.

Each of them is toxic to humans. If you occasionally get a small whiff of gas, it shouldn't be a problem.

But if the odor is strong or lasts more than a short time, you need to address the situation. Not only does the gas carry bacteria, but also it can replace the oxygen in your bathroom, which is a major problem, especially in small rooms.

How Often Should I Clean My Sink Drains?

To avoid clogs and bacteria buildup in your drainpipes, treat the drain monthly, as follows:

  1. Plug the sink
  2. Fill it to the top with water.
  3. Pull the plug. Water will rush down the drain, washing out debris and buildup.

Why Does A Dry P-Trap Smell?

The P-trap holds a small amount of water, filling the bottom of the bend in the pipe. This water creates a barrier that prevents sewer gases from wafting back up and out the drain. When the P-trap is dry, there is no barrier, and foul gases are free to rise from the sewer.

How Much Does It Cost To Replace A P-Trap Or Sink Trap?

Replacing a P-trap or other sink trap is a relatively simple job, and you can save substantial money if you do the work yourself. The cost of a new P-trap kit is under $20, and you can complete the repair within an hour or so. If you hire a plumber, you may pay $150 or more.

In Closing

Address sewer or rotten egg odors in your bathroom right away. These gases not only smell bad, but they also contain bacteria and can choke the oxygen out of a small bathroom. Fortunately, it is fairly easy to diagnose and fix the problem if it is coming from your bathroom sink. If you prefer not to do the work yourself, call a plumber to get the issue repaired as quickly as possible.

You may also enjoy the following:

How To Get Rid Of Odor In The Bedroom [11 Ways]

How To Unclog A Bathroom Sink With Vinegar And Baking Soda

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