Why Does My Bathroom Sink Smell? – Reasons

Is your bathroom sink full of mysterious odors? Do you smell something nasty whenever you run water in the sink?

Although you have cleaned the basin and your counters multiple times, the unpleasant smell still lingers around the bathroom. If yes, we’re here to help you in tracking down all those mysterious funky smells in your bathroom sink.

Why Does My Bathroom Sink Smell

In this brief guide, we’ve compiled a list of all possible culprits that can cause your bathroom sink to smell extremely offensive.

Stinky Bathroom Sink:

Bathroom areas that are continuously exposed to moisture, especially bathroom sinks, are more prone to bacteria, mildew, or mold growth. Generally, bacteria buildup or sewer gases are the main culprits that make your bathroom stink to high heaven.

However, these aren’t the only reasons why your bathroom smells awful. Dry P-traps, clogged drains, blocked vents, broken “AAV” (air admittance valve), and contaminated water heater & pipes can also cause your bathroom sinks to smell like rotten eggs, sewer, musty, urine, or fish.

What Causes The Bathroom Sink To Smell Like Rotten Eggs Or Sulfur?

If your bathroom sink stinks like rotten eggs or sulfur, you might be having issues with biofilm or bacteria buildup.

Biofilm Buildup In The Sink Drain Pipes:

Biofilm buildup under the drain pipes creates an assaulting smell like rotten eggs. It piles up in the drains and pipes of your bathroom sinks. The dark, wet, and warm environment beneath the sink create an ideal home for smelly bacteria to thrive, resulting in black, slime-like gunk buildup (biofilm).

This dark, slimy gunk can be formed from a range of resources, including soapy water, facial cleansers, shaving creams, toothpaste, and dead skin cells that we wash down in the sink drain on a daily basis.

To check if you have biofilm buildup, either observe the water drain or unlatch and pull out the sink stopper. The water will drain slowly or unevenly if you have a biofilm buildup under the sink drains.

To Fix The Smell: If, after unlatching and pulling the sink stopper, you find it covered with black gunk, pour a vinegar solution into your drain pipes to eliminate it. If you don’t want to use vinegar, buy any cleaning product designed for biofilm reduction from the supermarket or online.

However, if your pipes are gravely filled with biofilm buildup, it is advisable to call a professional plumber. To clean drain pipes filled with biofilm buildup, you have to disassemble the drain pipes. Therefore, it’s better to take professional help rather than creating further plumbing issues.

Bacteria Buildup In Water Heater And Faucets:

If your sink smells like sulfur, the culprits behind the smell can be unused drains or contaminated water and pipes. Bacteria buildup in the pipes and faucets can release hydrogen sulfide gas (aka sewer gas). This gas can cause the water in the faucets to smell like sulfur or rotten eggs.

Additionally, bacteria buildup in the water heater feeds on corroded anodized rods. The rods in the water heaters prevent corrosion.

However, over time, these corroded anodized rods break down, resulting in water in the heater smelling like rotten eggs or sulfur. To check if your water heater is contaminated or not, simply compare a glass of water from the heater to the glass of freshwater from kitchen taps.

To Fix The Smell: To eliminate the smell from the water heater, install a new anodized rod on top of the heater element.

However, if the smell is coming from the contaminated faucets, sanitize your faucets. To sanitize the bacterial faucets, follow these simple steps:

  • Thoroughly mix 1 cup of vinegar, 1/2 cup of baking soda, and 1 gallon of water to make a solution.
  • Unscrew your sink faucet.
  • Dump the faucets in the vinegar-baking soda solution.
  • Scrub the inside and outside of your faucet meticulously with the solution.
  • Scrub and rinse the aerator thoroughly and screw it back into place.
  • Keep running the water through the faucet until the water comes out clean.

What Causes The Bathroom Sink To Smell Like Sewer?

If your bathroom sink is giving out a sewer smell, you might have issues with a dry p-tap, clogged sink drain, faulty or broken pipes.

Clogged Sink Drains:

Bits of hair, dirt, or paper towel can clog the sink drain, causing the water to unload unevenly and slowly. This makes the drainpipes an easy path for sewer gases to enter the bathroom. Clogged sink drains can raise sewer gases as the air pockets in the clog let the gases pass through them.

Bathroom Sink Smell Reasons

To Fix The Smell: The simplest and the quickest solution is to buy a bottle of drain cleaner from your nearby supermarket. Slowly pour the bottle down the sink drain to put an end to any accumulated sticky or messy substances that may have stored up in the pipelines and caused the bathroom to smell. The bad and unpleasant smell will, hopefully, fade away within 24 hours.

Dry P-trap:

The bathroom sink can smell like sewer if your water trap or p-trap is completely dried up. Underneath every sink in your home, be it in the kitchen or bathroom, you can notice a U-shaped bend in the pipe structure.

This U-shaped bend creates a water barrier between your home and the smells from the pipes attached to the sewer. When the p-trap is filled with water, the sewer gases from the sewer system will not be able to come through your bathroom sink,

However, if the water in the p-trap evaporates out completely, there will be no barrier to stop the sewer gases from entering the bathroom. Your p-trap can be dried up because you were away from the house for a week or two. The water in the p-trap may be evaporated completely during your vacation.

To Fix The Smell: Fortunately, fixing a dried-up water trap is pretty simple. All you have to do is run the water for a couple of minutes so that P-trap can be filled.

However, if you witness that your P-trap is evaporating more frequently and running the sink water isn’t enough to solve the problem, you can install a trap primer. The trap primer will automatically replenish water to the drain traps to prevent sewer gases and fishy smells from coming into your bathroom.

Broken Or Faulty Pipes:

Broken drain pipes underneath your sink can also dry up your P-trap, releasing sewer gasses to enter the bathroom.

In addition to a U-shaped water trap (P-trap), venting pipes also prevent sewer gases from entering the bathroom. Venting pipes force sewer gases out of the bathroom through your roof.

However, sometimes, especially during winter, these pipes get blocked or clogged with snow, leaves, or dust. When enting pipes get blocked, the sewer gases get down to sink drains, making your sink smell like a sewer.

To Fix The Smell: To fix leaky pipes and faulty vent pipes, it’s wise to call a professional plumber.

What Causes The Bathroom Sink To Smell Musty Or Dirt-like?

If your bathroom sink smells like dirt or musty, you might have mold or mildew formation in the drain pipes or anywhere underneath the bathroom sink.

Similar to clogged drains and biofilm formation, molds are also smelly and rather disgusting. Mold spores and mildew have a musty, dirt-like odor. Mold and mildew occur wherever water is present and trapped. For this reason, it is almost impossible to prevent mold spores and mildew growth in the bathroom sink.

Bathroom sink drains are exposed to water daily and, therefore, create a flourishing environment for mildew and molds to grow. The dark, wet, and full of bacteria drain pipes beneath the sink create an ideal home for mold spores to thrive. Molds in the bathrooms can also result from an unknown leak underneath the bathroom sink or wall.

To Fix The Smell: To clean mold or mildew, follow these simple steps:

  • Mix 2 tablespoons borax, ¼ cup white distilled vinegar, and 2 warm water to make a solution. Mix the solution until the borax is completely dissolved in the water.
  • Pour the Borax-vinegar solution on spaces affected by mildew or mold spores.
  • Wait for a couple of minutes for the solution to settle down.
  • Using a brush, scrub mold or mildew away.

What Causes The Bathroom Sink To Smell Like Urine?

If your bathroom sink smells like urine, there might be a chance someone had peed near it in the past. To be sure if somebody did or not, use a blacklight. Urine glows a kind of fluorescent yellow under the backlight.

Blacklight works best in the dark and, therefore, thoroughly checks your sink area, floors, walls with the help of it. If you find pee spots on your otherwise cleaned basin or floor, there is a high chance the pee smell is still lingering around the bathroom.

The Takeaway:

To conclude, a range of reasons can cause your bathroom sink to smell odious. Once you have gone through all the above-mentioned reasons, you probably would have tracked down the main culprit behind the offensive smell in our sink.