Bathroom Sink Odor – Dealing With Sewer, Rotten Egg & Musty Smells

Does your bathroom sink drain stink?

Are you worried about that sewer, musty and rotten egg smell in your bathroom sink? Here are some practical steps to fix this septic odor problem.

One of the most unpleasant odors you’ll like to avoid is those from septic tanks. These tanks don’t need to be open before they smell. Instead, malfunctioning creates a situation where you perceive such odors.

You could perceive the smell of your septic tank in your bathroom, basement, or other indoor areas.

Now, what’s responsible and how can these odors be eliminated?

Dealing With Septic Tank Smells In Bathroom

Here, we’re discussing the causes of septic tank smells in the bathroom and other indoor areas. The purpose is to inform and educate you on what can be done to get rid of such odors.

Sometimes, such sewer smells come from outside the house.

If you have odor issues only when it rains, here is a fix.

Dangers of Sewer Gas

The awful smell you’re inhaling from your septic tank is sewer gas which isn’t supposed to be released indoors. Perceiving this smell in your bathroom simply means your septic tank isn’t functioning right and needs to be fixed immediately.

There are lots of dangers associated with sewer gas finding its way into homes. These dangers can be categorized into health risks as well as explosive risks.

To be clear, the smells you perceive from your septic tank aren’t dangerous at low levels. However, it needs to be eliminated.

On the other hand, when a substantial amount of sewage gas leakage happens, it becomes toxic. This creates a significant health risk for you.

  • Health Risks

The characteristic smell of sewer gas (like the smell of rotten eggs) isn’t only awful by could cause health problems.

This is even more common when the leakage from your bathroom is significant. Symptoms of exposure range from lightheadedness or dizziness, and fatigue.

Others include poor concentration and memory, headaches, as well as nausea. Mild symptoms will normally go away without treatment once you’re no longer inhaling this odor.

In extreme cases where significant levels of sewer gas are inhaled, symptoms will include loss of smell, coma, seizures, pink eye and eye irritation, as well as throat and lung irritation.

Prolonged exposure to sewer gas at high levels may likely lead to death. However, the smell emanating from your septic tank wouldn’t be as high as to cause these severe symptoms. Nevertheless, these odors aren’t pleasant and will need to be gotten rid of.

  • Explosive Risk

Sewer gas leaks can also cause other problems such as explosions due to what it contains. Its components include hydrogen sulfide, methane, ammonia, and carbon dioxide.

Now, both hydrogen sulfide and methane gases are highly flammable and could result in explosive reactions when ignited by sparks or flame.

Why Do I Perceive Septic Tank Smells In My Bathroom?

Why does the bathroom smell like sewer after a shower?

This is the main question that needs to be asked by anyone faced with septic tank odors in the bathroom or other indoor environments. This smell may be faint or pronounced.

Whatever the case is, it isn’t supposed to be there in the first place. So, immediate solutions need to be found.

Before settling for a solution, you’ll need to first identify where such a smell is coming from. Septic tank odors in a bathroom are likely to emanate from multiple sources or particular points.

This depends on what the underlying problems are.

  • Understanding How Your Plumbing Works

Most plumbing is designed with a U-shaped pipe that serves or channels wastewater from the sink drain to the P-trap pipe. The P-trap serves an important function as one end connects to your septic tank or sewer system while the other goes up the roof to safely dispose of sewer gases while letting in the fresh air.

This similar setup applies to your shower and tub.

The P-trap is called so because while it channels wastewater away, it collects or traps a small amount. This trapped water serves as a blockage or barrier that prevents smelly odors that may enter your home from your septic tank.

All drainage systems have this structure that blocks off sewage gases from coming in. So, perceiving septic tank odors in your bathroom is an indication that something’s wrong.

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Sewer Gas Smell In Bathroom: 3 Situations

When septic tank odors are perceived in bathrooms, it could be due to 3 possible causes or a combination of them.

If the odors persist after trying out these three, the problems may be more complex and will require calling a professional to assess the situation.

  • Your Bathroom Hasn’t Been Used in a While

Bathrooms normally see frequent usage. However, there are times when you may not be home for extended periods.

During this time, the water barrier meant to block sewage gases from entering your home may be dried up.

When this happens, gases from your sewage tank easily enter your bathroom. This may be the cause of the odor you perceive. Luckily resolving this problem isn’t complex. You only need to flush some water down your drains to replenish the lost water.

  • Leakage in and Around your P-Trap

Unlike the first, it’s possible to still perceive septic tank smell despite using your bathroom frequently. So, the cause wouldn’t be due to dried-up water in your P-trap. Rather, there could be a leakage in and around your P-trap.

This means water doesn’t stay but leaks out. However little such leakage is, it opens up a path for septic tank odors to get into your bathroom. Fixing this problem will require calling a plumber to take a look.

  • Clog In Your Drain

Another possible cause for septic tank smells in your bathroom may be a clog in your drain.

The problem here may be easy to fix or a bit more complex. You could use a plunger to get rid of the smelly clogs yourself or call a plumber to get the job done.

A more challenging situation will require the removal of the P-trap to fix the problem. This may end up giving you the relief you seek.

What Causes Sewer and Musty Smell in Bathroom Sink?

If you’ve noticed your bathroom sink giving off a horrible sewer-like or musty smell, it’s possible due to a buildup of mildew and gunk. With constant use, there’s a steady buildup of residue and bacteria.

Also, such smells might be due to several factors such as clogged or blocked pipes, and biological slime.

Other possible causes of sewer and musty smells in the sink include cracked or clogged vents, and a dry P-trap. Water heater issues are also likely to cause smelly bathroom sinks.

All of these possible causes have to be investigated and resolved for the elimination of such smells.

Let’s take a look at each of these points.

  • Sulfur Bacteria

One of the primary causes of your bathroom sink smelling like a sewer is the presence of sulfur bacteria. This can be traced to the combination of bacteria with sulfur compounds.

This mostly happens in water distribution systems as well as groundwater and wells.

A chemical reaction results whereby hydrogen sulfide gas is created. By entering through your plumbing systems and pipes, you’re able to perceive it in your bathroom sink.

This also extends to other areas like kitchen sinks etc.

  • Clogged or Blocked Pipes

A musty smell can also be perceived when there’s a clogged or blocked drainage pipe. The longer this is allowed to sit without fixing the problem, the worst the problem becomes.

This is because there’s a significant buildup of bacteria that leads to unpleasant smells.

A quick fix or solution will be to have the pipes unclogged. The services of an expert technician such as a plumber will prove useful in resolving this problem.

  • Biological Slime

What’s this about? Biological slime simply refers to the end product of the mixture of shampoo and caked-on soap with hair, and skin oils.

This happens more often when the drain isn’t cleaned frequently. Are you wondering how such drains are cleaned? We’ll be looking at that shortly.

Biological slime creates an unpleasant experience as it gives off a musty smell that may be coupled with a sewer smell.

  • Cracked or Clogged Vents

Sewer and musty smell in bathroom sink can sometimes be traced to sewer smell in your bathroom sinks. Such clocks may be due to debris accumulation, while cracks may appear on iron vents.

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To prevent the constant escape of sewer gas through your bathroom sink, you’ll need to have your vent checked.

A professional plumber will have to be called to perform basic checks. Your suspicions may either be confirmed or disproved.

Whatever the case may be, the main objective should be to find the fault and have it resolved.

  • Dry P-Trap

If you’ve been away for a considerable amount of time, you might return to a smelly bathroom sink. Under such circumstances, you may wonder where such smells are coming from.

A dry P-trap could be the reason why you’re perceiving sewer and musty smells.

If your suspicions are true, then running multiple flushes should help resolve the problem. A dried P-trap is open to sewer gas leaks without the protection of a water barrier. Flushing helps replenish the dried water barrier.

You should experience a marked improvement after such flushes.

  • Water Heater Issues

How do water heater problems extend to your bathroom sink? In more ways than you can imagine. To be clear, this isn’t a problem you’ll experience a lot.

In other times, this cause of smelly bathroom sink isn’t as common as the others. Nevertheless, it’s a possible cause you have to consider.

A water heater that’s rarely turned or used at high temperatures will lead to the formation and growth of bacterial colonies. When this happens, a sewer-like smell develops.

This is characterized by its rotten-egg odor that’s very unpleasant.

A quick fix will be to heat the water to the highest possible temperature before flushing it out. This helps get rid of the bacteria. You may have to repeat the process multiple times to fully resolve the problem.

Awful Sewer Signals Danger

Apart from having to inhale awful sewer smell, you should also know that such smell is occasioned by leakage of sewer gases. These are highly dangerous when inhaled.

So, while perceiving sewer smell, it should be the least of your worries due to the health risks posed by dangerous gases like methane.

Methane does a lot of damage to you when you’re exposed to significant amounts of it. Plus, it’s more deadly due to its highly flammable nature. This can lead to explosions when a fire is mistakenly ignited.

At high exposure rates, symptoms include dizziness, headaches, and vomiting in addition to suffocation.

Resolving Septic Smells In Bathrooms

Septic tank smells in bathrooms are among common problems that arise from time to time. The escape of sewer gases from your tank into your home can be resolved through any of the methods mentioned above.

By now, you should know you’re having a septic tank smell in your bathroom. These awful smells shouldn’t be tolerated or ignored but fixed immediately with the strategies outlined above.

How To Remove Odor From Bathroom Sink

A smelly sink can be fixed in many ways. These include using a plunger to remove clogs and also pouring down hot water down the drain.

Other possible fixes include the use of caustic soda as a degreasing agent, pouring some white vinegar down the drain, and removing & cleaning the U-bend.

None of the above fixes may give any significant results.

In such situations, it’s best to call for professional help. A plumber will help you trace the problem in little to no time and have it fully addressed.

The different causes of sewer and musty smell have been discussed above. It’s important to check for any of these causes and have them resolved to limit your exposure to sewer gases.


Sewer and musty smells are very awful and signal a clear anomaly with your plumbing system. This may be experienced wherever your plumbing is hooked to.

One of the possible areas in your bathroom sink. Do you perceive such smells coming from this area? The normal thing to do will be to find out its causes.

What makes a bathroom sink have a sewer and musty smell? Without a doubt, it’s a clear sign of trouble that needs to be probed. We’re all about finding out why, or the origins of such smell.

Are you wondering why this happens?

This article should have helped answer all your pressing questions as well as how to fix the problem.

1 thought on “Bathroom Sink Odor – Dealing With Sewer, Rotten Egg & Musty Smells”

  1. Thanks for pointing out how a pungent smell that roams around your kitchen or bathroom sink is a sign that your drains are clogged and need cleaning. This happened to my boss recently, and he has stopped using his master’s bathroom because of it. Maybe he should reach out to a rooter that can clean his drains for him!


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