Walking into your bathroom and smelling sewage is never pleasant. That rotten egg or sewer odour coming from your shower drain can make your whole home feel unclean, even when everything else is spotless. The good news is that most shower drain smells have identifiable causes and practical solutions—some you can tackle yourself, and others that require a licensed plumber.
In this guide, we explain the five most common reasons for a sewage smell from shower drain and what you can do about each one. You’ll learn when a quick DIY fix is enough and when it’s time to call our team at Antons Plumbing & Gas for a thorough inspection and repair.
Key Takeaways
- A dry P-trap is the most common cause of sewer gas escaping into your bathroom.
- Biofilm buildup from soap, hair, and body oils can produce foul odours inside drain pipes.
- Blocked or slow drains trap decomposing organic matter that smells like rotten eggs.
- Leaking pipes behind walls or under floors allow hydrogen sulfide gas to enter your home.
- Faulty or missing vent pipes disrupt airflow and let sewer smells back up through drains.
- Professional CCTV drain inspections pinpoint hidden blockages, leaks, and venting issues.
Why Does My Shower Drain Smell Like Sewage?
Shower drains are designed to carry wastewater away while blocking sewer gases from entering your home. When that system fails, you notice the smell immediately. The odour is usually hydrogen sulfide gas, which smells like rotten eggs and is produced by bacteria breaking down organic waste in your plumbing.
Several factors can disrupt the protective barriers in your drain system. Some are simple maintenance issues, while others point to deeper plumbing problems that need professional attention. Understanding the root cause helps you choose the right fix and avoid wasting time on temporary solutions.
5 Reasons for Sewage Smell from Shower Drain
Sewage smells from a shower drain usually happen when sewer gas escapes through a failed water seal, trapped organic buildup, pipe damage, or poor ventilation in the plumbing system. While the odour might seem like “just a smell,” it often points to a specific fault that can worsen over time if ignored. Identifying the most likely cause is the fastest way to choose the right fix and restore a fresh-smelling bathroom.
1. Dry P-Trap Causing Sewer Gas to Escape
The water seal in the P-trap evaporates in rarely used bathrooms, allowing sewer gas to rise through the drain until the trap is refilled or repaired.
2. Biofilm Buildup Inside Drain Pipes
Soap scum, body oils, and hair form a sticky layer where bacteria thrive, creating persistent rotten odours even when the drain isn’t fully blocked.
3. Blocked or Slow Drains Trapping Organic Matter
Partial clogs hold decomposing debris in the line, releasing sewage-like gases and often causing slow drainage, pooling water, or gurgling sounds.
4. Leaking Pipes Allowing Sewer Gas Into Your Home
Cracked pipes or failed joints—often hidden behind walls or under floors—can vent sewer gas into the home and may also lead to mould or structural damage.
5. Faulty or Missing Vent Pipes Disrupting Airflow
Blocked or damaged vents create pressure problems that siphon traps dry or force sewer gas back through drains, often affecting multiple fixtures at once.
If the smell disappears after running water briefly, a dry trap is likely the culprit—but recurring odours usually indicate buildup, a blockage, a leak, or venting problems. The sooner you pinpoint the cause, the easier and cheaper it is to fix before it turns into a larger drainage or moisture issue. When in doubt, professional diagnosis (especially with CCTV inspection and leak detection) ensures the problem is solved at the source, not masked temporarily.
How We Fix Sewage Smells from Shower Drains
Sewage smells coming from shower drains usually mean there’s a seal failure, a buildup issue, a leak, or a ventilation problem allowing sewer gases to escape. Once we diagnose the true cause, we apply the correct repair method to stop the odour at the source—not just cover it up with temporary fixes. Our approach is focused on safety, compliance, and long-term prevention.
- Fix dry or faulty P-traps. We refill the trap, test the seal, and replace the trap if it’s cracked, leaking, or non-compliant.
- Remove biofilm and blockages. We use high-pressure water jetting to scour the pipe walls and clear hair, soap residue, and organic buildup that causes odours.
- Locate and repair leaks accurately. We pinpoint leaks using acoustic or thermal detection, then repair or replace the damaged pipe section.
- Offer no-dig pipe relining where suitable. If excavation is disruptive, we install an epoxy liner inside the existing pipe to seal cracks and restore function.
- Correct ventilation and vent stack issues. We inspect the vent stack, clear obstructions, and ensure the system meets Australian Standards, including installing vent caps where needed.
- Document everything and back it with warranty. We provide photos, compliance records where applicable, and a lifetime labour warranty for peace of mind.
The right fix depends on what’s causing the smell, which is why proper diagnosis matters before any repair starts. Once the root issue is resolved, your bathroom stays odour-free and your drainage system performs the way it should. With compliant workmanship, documented repairs, and warranty protection, you can be confident the problem won’t keep coming back.
When to Call a Professional Plumber for Drain Smells
Some shower drain odours can be resolved with a quick rinse or a DIY cleaning solution. But if the smell persists, returns frequently, or is accompanied by slow drainage, gurgling, or visible water damage, it’s time to call a licensed plumber. Ignoring these signs can lead to bigger problems, including pipe corrosion, mould growth, and health risks from prolonged exposure to sewer gas.
Here are the key situations where professional help is needed:
- The smell returns within days of cleaning the drain. This suggests a deeper blockage, biofilm buildup, or a faulty trap that needs mechanical cleaning or replacement.
- Multiple drains in your home smell or drain slowly. This points to a shared blockage in your main sewer line or a venting issue that affects the entire system.
- You notice water stains, damp patches, or mould near the shower. These are signs of a hidden pipe leak that requires detection and repair.
- The drain pipe smells like rotten eggs even when the shower isn’t in use. This indicates a dry trap, cracked pipe, or venting problem that won’t resolve on its own.
- You’ve tried DIY fixes and the problem hasn’t improved. Persistent odours often have a root cause that requires diagnostic equipment and professional expertise.
At Antons Plumbing & Gas, we offer same-day service across Sydney, with no call-out fee and upfront fixed-rate pricing. Our plumbers arrive with CCTV cameras, high-pressure jetters, and leak detection tools, so we can diagnose the issue on the spot and present clear options for repair.
DIY Solutions vs Professional Repairs: A Quick Comparison
DIY fixes can work for minor causes of shower drain odours, especially when the issue is close to the surface or related to simple maintenance. However, sewage smells often return when the underlying cause is structural, deeper in the line, or linked to ventilation or leaks. This quick comparison helps you decide when a safe DIY step is enough and when it’s smarter to call a licensed plumber.
| Issue | DIY Solution | When to Call a Plumber |
|---|---|---|
| Dry P-trap | Run water for 1–2 minutes to refill the trap | Smell returns quickly or trap is cracked |
| Light biofilm buildup | Pour boiling water or baking soda solution | Smell persists or drain is slow |
| Visible hair or soap near drain | Remove manually or use a plunger | Blockage is deep or recurring |
| Slow drainage | Try a drain snake or enzyme cleaner | Water backs up or multiple drains affected |
| Hidden leak or vent issue | Not suitable for DIY | Always—requires detection and repair |
If odours return after a basic trap refill or cleaning, it usually means the problem is deeper than a surface-level buildup. Recurring smells, slow drainage, or backup across multiple fixtures are strong signs you need professional diagnosis and clearing. A licensed plumber can confirm the cause, fix it safely to Australian Standards, and prevent the issue from coming back.
Preventing Shower Drain Smells in the Future
Shower drain smells usually come back when biofilm rebuilds, hair and soap collect in the trap, or a P-trap dries out and allows sewer gas to escape. The best prevention is a simple routine that keeps water moving, keeps organic buildup from sticking to pipe walls, and catches early warning signs before they become blockages. These habits take minutes but can save you from recurring odours and emergency callouts.
- Run water through rarely used drains weekly. This keeps the P-trap filled and blocks sewer gas from entering the bathroom.
- Clear the drain grate after every shower. Remove visible hair and soap residue so it doesn’t travel deeper into the trap or waste line.
- Flush with boiling water every few weeks. A kettle of hot water helps dissolve soap scum, body oils, and light buildup before it hardens.
- Skip harsh chemical drain cleaners. They can corrode pipes and create hazardous fumes, so use enzyme-based cleaners for safer, gradual breakdown of organic matter.
- Manage hard water buildup. Consider regular descaling or a water softener if mineral deposits are narrowing pipes over time.
- Schedule CCTV checks if roots are a risk. Homes with mature trees near sewer lines benefit from periodic inspections to detect root intrusion early.
Consistency is what keeps drains odour-free—small actions done regularly beat big cleanups done rarely. If smells return quickly despite maintenance, that’s often a sign of a deeper blockage, venting issue, or hidden leak that needs professional diagnosis. With a preventative routine and early inspections when needed, you can keep your shower drain flowing cleanly and smelling fresh long-term.
Why Choose Antons Plumbing & Gas for Drain Odour Issues
When you call Antons Plumbing & Gas on 0493 824 176, you’re getting more than a temporary fix—you’re getting a proper diagnosis, clear options, and workmanship done right the first time. We’re a licensed, family-owned team with 25+ years’ experience helping Sydney homeowners, strata managers, and local businesses resolve persistent drain odours. Our plumbers operate under Lic: 210933C, follow NSW Fair Trading requirements and relevant AS/NZS plumbing standards, and deliver same-day service across Sydney with 24/7 emergency response and no call-out fee.
We use professional tools like CCTV drain cameras, high-pressure jetting, and acoustic leak detection to find the root cause—whether it’s biofilm, a dry or faulty P-trap, a blockage, a leak, or a venting issue. Pricing is upfront and fixed-rate, so you’ll know the cost before work begins, and we don’t use scare tactics or push unnecessary services. Every job is backed by our lifetime labour warranty, giving you long-term confidence that the smell won’t keep coming back.
Conclusion
A sewage smell from your shower drain is more than just unpleasant—it’s a sign that something in your plumbing system needs attention. Whether it’s a dry trap, biofilm buildup, blockage, leak, or venting issue, the right diagnosis and repair will restore fresh air to your bathroom and protect your home from further damage. Call Antons Plumbing & Gas on 0493 824 176 for same-day service and a solution you can trust.
Antons Plumbing & Gas specialises in blocked drain solutions and CCTV inspections to eliminate sewage smells. Our licensed team diagnoses the root cause and fixes it right the first time. Get started with same-day service today.
Related Articles
- How to Prevent Soap Scum in Shower Drain Before It Builds Up
- 5 Proven Tips on How to Dissolve Hair and Soap Scum in Pipes
FAQs
What Causes Sewage Smell From Shower Drain?
Sewage smells from your shower drain can be caused by a variety of issues, including a dry P-trap, clogged drains, or a build-up of bacteria and organic matter. Over time, debris such as hair, soap scum, and grease can accumulate, leading to odors that resemble sewage. At Antons Plumbing & Gas, our 25 years of experience equips us to accurately diagnose the root cause of these unpleasant smells.
How Do I Get Rid of Sewage Smell In My Shower?
To eliminate sewage smells from your shower, start by running hot water to clear any minor blockages. You can also try pouring a mixture of vinegar and baking soda down the drain to neutralize odors. If the smell persists, it may indicate a more serious issue requiring professional attention, and our team is available 24/7 to help resolve it safely and effectively.
Is Sewage Smell From Shower Drain Dangerous?
Yes, a sewage smell from your shower drain can pose health risks, as it may indicate the presence of harmful gases or bacteria. Prolonged exposure can lead to respiratory issues or other health concerns. If you detect a sewage smell, it’s essential to address the issue promptly, and our licensed professionals at Antons Plumbing & Gas can provide the necessary solutions while ensuring your safety.
Can A Clogged Shower Drain Cause A Sewage Smell?
Absolutely, a clogged shower drain can cause a sewage smell. When water cannot flow freely, it can lead to stagnant water and a build-up of organic matter, resulting in unpleasant odors. Our experienced team can perform thorough drain cleaning and inspections to clear clogs and prevent recurring smells.
How Do I Clean A Smelly Shower Drain?
To clean a smelly shower drain, start by removing any visible debris. Next, pour a mixture of baking soda followed by vinegar into the drain, allowing it to sit for about 30 minutes before flushing with hot water. For persistent odors or clogs, consider contacting Antons Plumbing & Gas, where we utilize advanced techniques and equipment to ensure your drains are clean and functioning properly.
January 2026
