You walk into your kitchen or bathroom and catch a foul odour that makes you pause. It smells like rotten eggs coming from your drain — and no matter how much air freshener you spray, it lingers.
A sulfur smell coming from your drain isn’t just unpleasant. It frequently indicates a problem with your plumbing system, such as a dry p-trap, a concealed blockage, or even sewage gas leaking into your house. You can promptly address the rotten egg smell before it gets worse or damages your plumbing if you know what’s causing it.
In this blog, we’ll explain why your drain smells like sulfur, the common causes behind that foul odour, and how to get rid of it using both DIY and professional solutions. We’ll also cover how to prevent drain odours from returning — and when it’s time to call a plumber in Toronto for help.
Don’t let that sulfur smell linger. Contact Absolute Draining & Plumbing — your trusted plumbers serving Toronto, Etobicoke, Mississauga, and the GTA.
What Causes That Rotten Egg or Sulfur Smell Coming From Your Drain?
Hydrogen sulfide gas, a result of bacteria and decomposing organic materials inside your pipes, is typically the source of the rotten egg stench emanating from a drain. While it’s not typically dangerous in small amounts, it’s definitely something you don’t want lingering in your home.
Here are the most common causes of that sulfur smell from drains:
1. Clogged or Partially Blocked Drains
A clogged drain is one of the most frequent culprits behind bad smells. When soap scum, hair, food scraps, and grease build up inside your drain pipe, they trap moisture and bacteria. As bacteria feed on this organic material, they release foul-smelling gases that make your sink or shower drain smell like rotten eggs.
Signs your drain may be clogged include:
- Slow-draining water
- Gurgling sounds from the drain
- A persistent unpleasant smell even after cleaning
Fix it:
Prepare 1 cup of baking soda and white vinegar. Then, pour it down the drain. Let the mixture fizz for about 10–15 minutes, then flush it with boiling water. This helps break down grease and organic matter, causing the odour.
If the smell still comes back, the clog might be deeper in your sewer line, and you’ll need professional drain cleaning.
2. A Dry or Damaged P-Trap
The p-trap is the U-shaped pipe under your sink or shower drain. It holds a small amount of water to block sewer gases from entering your home.
There is no longer a water seal to stop sewer gas from escaping when a p-trap dries out, which results in that distinct sulfur odour. This is especially common in rarely used sinks, guest bathrooms, or seasonal properties.
Simply run water down the drain for 30–60 seconds to refill the p-trap. If the smell disappears, the dry trap was the issue.
However, if the smell comes back quickly, there might be a crack or leak in the trap or a plumbing vent issue allowing sewer gas to back up.
3. Bacteria in the Drain or Garbage Disposal
In kitchen sinks, rotting food debris trapped in the garbage disposal or drain pipe can breed bacteria. Over time, this bacteria breaks down organic waste and releases hydrogen sulfide gas, causing that smelly drain odor that smells like sulfur or rotten eggs.
Try cleaning your garbage disposal with this quick method:
- Drop a few ice cubes into the disposal.
- Add a small amount of dish soap or a slice of lemon for freshness.
- Run the disposal for 30 seconds with cold water.
You can also use an enzyme cleaner designed for drains, which breaks down bacteria and organic matter naturally without harsh chemicals.
Note: Do not frequently use chemical drain cleaners because they can eventually corrode your pipes and harm your plumbing system.
4. Sewer Gas Leaks
If your drain smells like rotten eggs and the odour spreads beyond one sink or bathroom, you could have a sewer gas leak.
Sewer gas is a mix of methane, ammonia, and hydrogen sulfide — gases produced by decomposing sewage in your sewer line. It’s not only foul-smelling but can also cause headaches, nausea, or worse if inhaled in large amounts.
Possible causes include:
- A broken sewer line
- A cracked vent pipe
- A malfunctioning backwater valve
- Dry floor drains or p-traps
If you suspect sewer gas is coming from your drain, open your windows for ventilation and call a professional plumber immediately. A certified expert from Absolute Draining & Plumbing can inspect your drain pipes and sewer line to identify where the gas from the sewer is leaking.
5. Water Heater or Plumbing System Issues
Sometimes, the smell of sulfur isn’t from the drain itself — it might be coming from your water supply.
A common source is the anode rod in your water heater. This rod prevents rust, but over time, it reacts with naturally occurring sulfur in the water, producing a hydrogen sulfide gas smell that’s noticeable in both hot and cold water.
To check this:
Fill a glass of cold water from the affected sink and smell it outside. If the water smells like sulfur, the problem is in your water heater or plumbing system, not the drain.
You’ll need a licensed plumber to replace the anode rod or disinfect the system to eliminate the odour safely.
How to Fix a Sulfur Smell Coming From Your Drain
Once you’ve identified the cause of the odour, you can start taking appropriate action. Here is a list of the best DIY and professional methods for getting rid of drain odours.
1. Clean the Drain With Baking Soda and Vinegar
This simple, non-toxic solution works wonders for minor drain odours and buildup.
Here’s how:
- Fill the drain with 1 cup of baking soda.
- Add 1 cup of white vinegar after that.
- Give it 15 to 20 minutes to fizz.
- Flush with boiling water to rinse away loosened debris.
This combination naturally breaks down soap scum, grease, and organic material, causing bad smells in your kitchen or bathroom drain. Repeat weekly for maintenance.
2. Flush Out the P-Trap
If your p-trap dries out, sewer gases can easily enter your home.
To replenish the trap and restore the water seal, run hot water down the drain for a minute or two. After replenishing water in sinks that are rarely used, apply a spoonful of mineral oil to delay evaporation and prevent your drain from drying out again.
3. Use an Enzyme Drain Cleaner
Enzyme-based drain cleaners, in contrast to chemical drain cleaners, break down organic materials like hair, grease, and food waste inside your pipes using natural bacteria and enzymes.
They’re safe for your plumbing system and effective in maintaining clean, odour-free drains over time. Use them monthly in your kitchen sink, bathroom drains, and shower drain as a preventive measure.
4. Clean Your Garbage Disposal Thoroughly
If the kitchen sink smells like sulfur, the garbage disposal could be the main culprit.
Follow this deep-cleaning method:
- Disconnect power to the unit.
- Remove visible debris and rinse with warm water.
- Pour half a cup of baking soda, followed by white vinegar, and let it fizz for 10 minutes.
- Turn on the disposal with ice cubes and a lemon slice to scrub the blades.
- Flush with cold water.
This eliminates foul odours and prevents bacterial buildup that causes smelly drains.
5. Inspect the Plumbing Vent and Sewer Line
A blocked plumbing vent can prevent sewer gases from escaping outdoors, forcing them back through your drains. Likewise, a broken sewer line can allow sewage to leak and create foul smells around your home or yard.
Because these issues involve your main sewer system, they require professional inspection. At Absolute Draining & Plumbing, our licensed Toronto plumbers use camera inspection tools to locate blockages or leaks within your sewer line — minimizing guesswork and unnecessary digging.
6. Call a Professional Plumber
If after trying all of these innovative step, your drain still smells like sulfure. Then it’s time to consult and hire a qualified plumber if. Furthermore, chronic bad odours may indicate deep-seated drain pipe corrosion, hidden obstructions, or vent issues.
Professional drain cleaning services utilize specialized tools, including high-pressure flushing for sewer lines, video inspection cameras to find internal clogs, and hydro-jetting to remove stubborn buildup.
In Toronto and the Greater Toronto Area, Absolute Draining & Plumbing provides 25-year warranties on drain repairs, flat-rate pricing, and 24-hour emergency service. Whether it’s a bad-smelling kitchen drain or sewage stench in your basement, our plumbing crew will quickly and safely locate and fix the problem.
Contact us today for expert drain cleaning in Toronto, Etobicoke, Mississauga, and the GTA — call us or book your service online.
Stop the Rotten Egg Smell for Good With These Tips
Once your smelly drain is clean, keeping it that way is easier than you think. Here are practical maintenance tips to prevent the sulfur smell from returning.
1. Flush Drains Regularly
Pouring hot water down the drain frequently—ideally once a week—is a good idea. Because shower drains and bathroom sinks frequently gather organic materials like hair and other residues, this is particularly crucial.
2. Avoid Pouring Oils or Fats
Avoid pouring grease or cooking oil down the drain or sink. When these substances cool, they solidify, leading to a sticky buildup that can attract bacteria and debris. Instead, use paper towels to wipe down pans and dispose of them in the trash.
3. Use a Drain Catcher
A basic drain catcher keeps food scraps, hair, and soap residue from going down your drain pipes. It’s a cost-effective solution to prevent clogs that can cause unpleasant odours.
4. Keep Unused Drains Wet
To keep the p-trap from drying out in a guest bathroom or basement sink that you don’t often use, run water down the drain once a week or two. To slow evaporation, add a teaspoon of mineral oil.
5. Maintain Your Plumbing System
Arrange for yearly drain inspections by a qualified plumber. They are able to identify initial indicators of blockages, corrosion, or damage to the sewer line that may lead to unpleasant odours or flooding over time.
When to Call a Toronto Plumber for a Smelly Drain
If your drain smells like rotten eggs and the odour doesn’t go away after cleaning, it’s best to get professional help. You should call a plumber if you notice a smell affecting multiple drains or rooms, you hear gurgling sounds or see slow drainage, the odour worsens after heavy rain or plumbing use, or if you suspect sewer gas leaks or sewage backup.
Ignoring these signs can have a number of detrimental effects, including health hazards, mould growth, and water damage.
Absolute Draining & Plumbing provides expert drain cleaning, sewer inspection, and repair services across the Greater Toronto Area. With over 20 years of experience, our team uses modern tools and proven techniques to eliminate unpleasant odours and restore your plumbing system to perfect working order.
If DIY fixes haven’t helped, it’s time to call the pros. Contact us for reliable drain and sewer services across Toronto, Etobicoke, and Mississauga.
Enjoy Fresh, Clean Air — No More Rotten Egg Odours!
More than just an irritation, a sulfur or rotten egg stench emanating from your drain is a sign that something is amiss with your plumbing. It’s important to take quick action before the problem worsens, whether it’s a clog, a dry p-trap, or sewage gas.
By using natural solutions like baking soda and vinegar, maintaining your p-traps, and scheduling regular professional drain cleaning, you can keep your drains odour-free all year round.
If you’ve tried everything and the smell still comes back, don’t wait — contact Absolute Draining & Plumbing. Our trusted Toronto plumbers are available 24/7 to inspect, clean, and repair your drains safely and efficiently.
