Post By Admin
June 5, 2025Sometimes, a bad day starts from a terrible shower experience. Imagine getting a shower in the morning with a smelly shower drain. Yuck! A smelly shower drain is a common issue many homeowners face, and it can quickly turn your bathroom into an unpleasant space.
In Melbourne, changing weather patterns, high humidity levels during winter, and a diverse architectural mix of historic Victorian cottages and modern apartments make bathroom drainage and odor issues particularly prevalent. As one of Melbourne’s trusted blocked drain specialists, we’re here to help.
In this article, you’ll find simple, effective ways to fix the smell, diagnose underlying plumbing hazards, and stop it from coming back.
What Causes Your Shower Drain to Smell Like Sewage
It’s not easy to put up with a shower drain that smells like sewage. But first of all, it’s best to identify the exact causes behind this disaster before pouring chemicals down your pipes or taking things apart.
1. Dirty P-Trap
Let’s start with the usual suspect: the P-trap. This curved pipe under your shower is designed to hold water and block sewer gases from entering your home.
But when it dries out or gets coated with gunk, guess what? The gases sneak through—resulting in a shower drain that stinks.
In multi-storey Melbourne homes or apartments with guest bathrooms, indoor heating during our cool winters can actually accelerate water evaporation inside the pipes, leaving the trap totally dry within a few weeks. Furthermore, stagnant water sitting inside the bend can accumulate a slimy bacterial layer called biofilm that emits a foul smell like rotting cabbage.
If your bathroom suddenly smells like rotten eggs, there’s a good chance the P-trap is either dry or dirty. This issue is especially common if the shower hasn’t been used in a while.
Run some water to refill the trap, and if the smell sticks around, cleaning it out might be your next move.
2. Buildup of Hair, Soap Scum, and Gunk
Over time, hair, soap, dead skin, and other debris can build up in your shower drain. This not only slows down drainage—it also becomes a breeding ground for bacteria.
And when bacteria break down this gunk? Yep, you get that awful smell that makes you want to leave the bathroom immediately. If your smelly drains in the bathroom are getting worse each day, there’s likely a nasty buildup forming just out of sight.
When body oils, thick hair conditioners, and dead skin cells mix with natural minerals in the water supply, they form a hardened, dark sludge along the pipe walls. This organic sludge slowly decomposes right under the drain grate, constantly releasing sulfur gas into your shower cabin.
You can try removing the blockage with a drain snake or use a safe enzyme cleaner to break it down.
3. Mould and Mildew in the Pipes
Your bathroom is the perfect place for mould and mildew to thrive—especially in damp, dark drains. These fungi not only affect air quality but can also create musty odours that get mistaken for a sewage smell.
Melbourne’s naturally damp and cold winter months often prevent bathrooms from drying out completely between showers, which dramatically accelerates fungal growth right below the drain grate.
Peek around the drain cover—if you see black spots or smell something earthy and unpleasant, mould might be the problem. A proper cleaning with a mould-killing solution should help banish the smell and protect your household from breathing in potentially harmful fungal spores.
4. Vent Pipe Blockage
Your plumbing system has vent pipes that let sewer gases escape outside. But if one of those vents gets blocked by debris, leaves, or even a bird’s nest, those gases can’t escape. Instead, they get trapped and force their way back up through your drains.
Fallen leaves from plane or gum trees and even native possums or birds seeking shelter on your roof frequently choke these vital ventilation shafts. If your shower drain emits a hollow gurgling sound whenever you flush the toilet or run the bathroom sink, a blocked roof vent is almost certainly the culprit.
When your shower drain stinks and none of the usual fixes work, it could be a venting issue. This is where calling blocked drain specialists (like us!) can save you the headache of climbing onto the roof or digging into your walls.
5. Damaged or Collapsed Underground Pipework
If you live in an older property with original terracotta or earthenware plumbing, invasive tree roots actively seek out moisture and can easily fracture your underground drainage pipes.
When a pipe breaks or collapses beneath your foundation or garden, raw wastewater leaks into the surrounding soil, sending a persistent, heavy sewage odor straight back up through your shower drain that no amount of surface cleaning can fix.
Now, you have the answer for your question, let’s move on to the best solution you can try!
How to Get Rid of the Smell in Your Shower Drain
Without further ado, let’s discuss some things you can do to get rid of the shower drain smells:
1. Identify the Root Cause
Before you do anything else, figure out why your shower drain stinks. Is it a dry P-trap? A buildup of hair and gunk? Or Mould?
Knowing what you’re dealing with will help you choose the right fix—rather than throwing random solutions at the problem.
Take a few minutes to inspect the drain and use this quick diagnostic checklist to narrow down the issue:
| Symptom or Smell Type | Likely Primary Cause | Recommended First Step |
|---|---|---|
| Sharp “rotten egg” or sewage smell | Dry P-trap or blocked roof vent | Run hot water for 2 mins; listen for gurgling |
| Heavy, musty, or damp earthy odor | Mould and mildew buildup | Inspect under the grate for black fungal spots |
| Rotting odor combined with slow water pooling | Sludge, hair, and soap scum clog | Manually extract gunk with a drain snake |
| Persistent raw sewage odor outdoors & indoors | Broken or root-damaged pipe | Call a licensed plumber for a CCTV inspection |
Once you’ve got a clue, move on to the fix that fits.
2. Flush the P-Trap
If your shower hasn’t been used in a while, the water in the P-trap may have evaporated—letting those nasty gases rise up. The simplest solution? Just refill the trap.
Try this:
- Turn on the shower and run warm water for 1–2 minutes.
- Add a small amount of mild soap or white vinegar to help rinse away any grime.
Pro Tip for Guest Bathrooms: If you are going away on an extended holiday or have a spare bathroom that is rarely used, pour two tablespoons of plain mineral oil or baby oil down the drain right after running the water. The oil floats securely on top of the water seal inside the trap, creating an airtight barrier that completely stops the water from evaporating over long periods.
If the smell fades, the P-trap was likely the problem. If it doesn’t, keep reading.
3. Use Baking Soda and Vinegar
This classic DIY fix is safe, natural, and surprisingly effective—especially for breaking down organic gunk and deodorising smelly drains in the bathroom.
Here’s how to do it:
- Pour ½ cup of baking soda into the shower drain.
- Follow it with 1 cup of white vinegar.
- Let it fizz and work its magic for 15–30 minutes.
- Rinse with a full kettle of boiling water.
Crucial Safety Note: While boiling water works wonders on traditional copper or metal pipes, avoid using rapid, roaring boiling water straight from the kettle if your home utilises modern PVC plastic drainage piping. Extreme and sudden temperature spikes can soften the plastic or degrade the glue joints over time. Very hot tap water is a much safer alternative for plastic plumbing.
Do this once a week to keep your drain fresh and clear.
4. Remove Physical Blockages
If your shower is draining slowly and smells gross, it’s time to unblock the drain manually. Hair, soap scum, and other debris often get trapped just below the surface.
To unblock a drain:
- Remove the drain cover (you might need a screwdriver or a pair of needle-nose pliers).
- Use a gloved hand or a drain snake to pull out any visible gunk.
- If a manual snake is not grabbing deep enough, place a wet/dry shop vacuum over the drain opening. Then, wrap a wet rag around the edges to create a tight seal and run the vacuum on liquid mode for 30 seconds to suck up stubborn hair clumps.
- Rinse the area with hot water.
- Spray with a disinfectant or vinegar solution to kill lingering bacteria.
Gross? Yes. But incredibly satisfying.
5. Try (Safe) Chemical Drain Cleaners
If DIY methods don’t cut it, you can try chemical drain cleaners—but use them with caution. Harsh chemicals can damage pipes, especially older ones, and they’re not ideal for regular use.
If you go this route:
- Read the label carefully.
- Use in a well-ventilated room.
- Pour the recommended amount directly into the drain.
- Wait the specified time, then flush with hot water.
Pro tip: Always try baking soda and vinegar first. It’s safer for your pipes and the environment. In Victoria, strict environmental guidelines actively discourage pouring highly corrosive, caustic acid cleaners into the wastewater network. This is because they can destroy the rubber O-rings inside your pipe joints and disrupt local sewage treatment facilities.
6. Switch to Bio-Enzymatic Drain Cleaners
Instead of relying on harsh supermarket acids, opt for a professional-grade bio-enzymatic drain cleaner. These eco-friendly and non-toxic formulations introduce millions of beneficial, naturally occurring bacteria into your plumbing.
Over several hours, these microbes literally feed on and digest organic matter, including hair, soap scum, body oils, and biofilm, turning them into harmless water and carbon dioxide.
Leaving an enzyme cleaner to sit in your shower drain overnight once a month is one of the safest ways to permanently eliminate odour-causing bacteria without risking chemical pipe damage.
7. Call in the Blocked Drain Specialists
Still smelling something awful no matter what you try? It might be a deeper issue—like a blocked vent pipe, damaged seals, or stubborn clogs deep in the system.
This is when it’s best to call the pros. As one of the blocked drain specialists, we’ve seen (and smelled) it all—and we know exactly how to fix it fast and safely.
Equipped with high-definition CCTV drain cameras and industrial-grade hydro-jetting machines, our licensed plumbers can inspect the deepest corners of your plumbing network, pinpoint hidden tree root intrusions or cracked earthenware pipes, and blast away decades of compacted sludge without needing to dig up your bathroom tiles.
Don’t wait too long. The longer you leave a smelly shower drain, the worse it gets.
FAQ about Smelly Shower Drain
How to get rotten egg smell out of the shower drain?
That “rotten egg” smell usually means sewer gas is escaping, often due to a dry or dirty P-trap. Start by running warm water down the drain to refill the trap.
If the smell persists, try pouring a mix of baking soda and vinegar down the drain, let it sit for 15–30 minutes, then flush with boiling water. If none of that works, there might be a deeper issue—like a blocked vent pipe or mould buildup.
Can shower drain smell if not used?
Absolutely! If the shower hasn’t been used in a while, the water in the P-trap can evaporate.
Without that water barrier, sewer gases can rise right up into your bathroom. That’s why unused drains are common sources of unpleasant smells.
Is it okay to pour boiling water down the shower drain?
Yes—in most cases, it’s perfectly fine. Boiling water can help flush out soap scum, loosen grime, and even kill bacteria.
Just be careful if you have older metal or PVC pipes, as extreme heat might cause damage over time. For regular maintenance, hot (not boiling) tap water is a safer bet.
How often should you pour water down an unused drain?
If you’ve got a rarely used shower, it’s a good idea to pour water down the drain about once every 2–4 weeks.
This helps keep the P-trap full and prevents those nasty smells from sneaking into your bathroom. Adding a bit of vinegar along with the water can help keep things even fresher.
Why does my shower smell worse when it rains in Melbourne?
During heavy downpours and stormy weather, sudden drops in atmospheric pressure combined with overloaded municipal stormwater and sewer networks can actually push sewer gases backward through residential drainage systems.
If your home’s P-trap seal is low, or if your roof vent is partially obstructed by damp autumn leaves, rainy weather will force that trapped sewage odor straight out of your shower drain.
Conclusion
Don’t let a smelly shower drain ruin your day. With the right steps, you can fix the issue and keep your bathroom fresh.
Still dealing with stubborn odours that simply won’t go away? Even if you are dealing with a simple stubborn blockage in a modern apartment or complex tree root damage in a historic property, contact Neighbourhood Plumbing!
We’re ready to help you tackle the problem fast and professionally. Book your service today and breathe easy again!
About the Author
From unclogging the toughest drains to repairing leaking toilets, Ricky is a seasoned plumber who has brought his craftmanship to homes across Melbourne. He is passionate about sharing plumbing tips just as much as he is about fixing your plumbing issues. So, when your taps or pipes begin leaking, you know who to call.
