Smelly shower drain? Here’s how to fix it

You step into the bathroom and cop a whiff of something foul coming up from the shower. Or maybe the water pools around your feet every time you have a wash. Either way, it needs sorting out.

Smelly and slow shower drains are dead common in Melbourne homes. Most of the time the fix is straightforward. Sometimes it points to something bigger going on underground. Here is what causes it, what you can try yourself, and when to give us a call.

Why does my shower drain smell?

A stink coming from your shower drain means something is off below the grate. There are a few usual suspects.

Hair, soap scum and body oils

Over time, hair, soap residue, dead skin and oils from shampoo and conditioner collect inside the drain. This gunk forms a sticky layer that breeds bacteria. The bacteria break it down and release gas. That is the smell.

Mould and bacteria

Shower drains are dark, wet and warm. Perfect conditions for mould and bacteria to thrive. As they grow they release gases that give off a musty, rotten stink.

If your drain smells musty, mould is the likely culprit. Mould spores release gas that can be harmful if inhaled over time. A small patch can be cleaned with a mould-specific cleaner from your local supermarket. If it covers a larger area or keeps returning, you need a plumber to check the pipe.

Biofilm build-up

Biofilm is a slime filled with bacteria and bacterial waste that coats the inside of your shower drain and tiles. It produces a mildew-like smell and can harbour Salmonella, E. coli and other nasties.

To remove it, use a brush or scraping tool and move it in and out of the drain to clear as much slime as possible. Spray the area with an antimicrobial cleaner and leave it for a few hours.

Dry P-trap

If the smell is coming from a shower that has not been used in a while, the P-trap has probably dried out. The P-trap is a U-shaped bend in the pipe that holds a small amount of water. That water acts as a seal against sewer gas. No water, no seal, and the gas rises straight into your bathroom.

Run the tap for 30 seconds and the smell should clear. If it does not, pour two cups of water down the drain and wait an hour. Shine a light down the drain - if you can see the water sitting there, the problem should resolve. If you cannot see water, there may be a crack in your pipes and you will need a professional drain inspection.

Sewer gas

If your shower drain smells like raw sewage, the cause could be more serious. A cracked vent pipe, a broken seal, or a blockage deeper in your sewer line can all let sewer gas escape into the house. This type of smell will not sort itself out. You need a plumber to take a look.

Drain clog

A telltale sign of a clogged drain is that your shower drains slowly, or not at all, with an odour accompanying the poor drainage. Common culprits include soap scum, hair, dirt and small items. A hand auger can be used to fish out debris, but use it carefully to avoid damaging pipes. If in doubt, call your local plumber.

What to do when your bathtub won’t drain

A bathtub that will not empty or drains painfully slowly is usually caused by one of these:

Common causes

• Hair and soap tangled together in the waste pipe, gradually choking off the flow.
• Residue from bath oils, salts and other products clinging to the pipe walls and trapping debris.
• A blocked vent pipe stopping proper airflow in the plumbing system, which slows drainage or causes gurgling.
• Old or misaligned pipes that have sagged or shifted over the years.

What you can try at home

Pour a kettle of boiling water slowly down the drain. This can dissolve soap scum and loosen light build-up.

Try a plunger. A few firm pumps can shift small clogs sitting close to the surface.

Use a drain snake. A basic manual snake from Bunnings can pull out hair and gunk from deeper in the pipe.

If you have tried all three and the water still will not budge, or the drain blocks up again within a week, the problem is further down the line. A damaged pipe or a blockage deeper in the system needs proper gear to diagnose. We use CCTV drain cameras to find exactly what is going on before we touch anything.

Preventative maintenance tips

A few simple habits will keep your drains clear and stop the smell from coming back.

Use a drain strainer

Stick a mesh strainer over the shower drain to catch hair before it goes down the pipe. They cost a couple of dollars and save you from most blockages.

Keep oils and greasy products to a minimum

Bath oils and heavy conditioners leave residue that sticks to pipe walls and traps everything else. If you do use them, flush the drain with hot water afterwards.

Clean regularly

Wipe around the drain and keep soap scum off the shower floor. A quick scrub of the tiles once a week makes a difference.

Use enzyme-based cleaners

Skip the harsh chemical drain cleaners. Enzyme-based products use natural bacteria to eat through organic build-up in the pipe. They are gentler on your plumbing and safer for the environment. Once a month is plenty.

If you want to know more about why we recommend staying away from chemicals, read our guide on why you should avoid chemical drain cleaners.

When to call Drainpro

DIY fixes handle the simple stuff. But if the problem keeps coming back or gets worse, you need a pro. Here is when to pick up the phone:

• The shower drain smells like sewage even after you have cleaned it
• More than one drain in the house is blocked or smelly
• You have tried the home remedies and the issue returns within days
• Water is backing up into the shower or bathtub
• You hear gurgling sounds from the drain, which usually means a blockage further down

We carry high-pressure water jetters and CCTV cameras on every truck. We find the problem, show you the footage, and fix it on the spot in most cases.

With over 25 years in drain cleaning and repair, no plumbing problem is too complex for our team.

Need a hand with a smelly shower or a blocked bath? Call us on 1300 303 247 or fill in our online contact form. We service all of Melbourne and we do not muck around.

FAQ

Why does my shower drain smell even if it is not clogged?

Usually bacteria, mould, or a dry P-trap. Organic gunk builds up inside the pipe over time and creates odour even when water drains fine. If the shower has not been used recently, run the tap for 30 seconds to refill the P-trap.

Why does my shower drain smell like sulfur?

A sulfur or rotten egg smell usually means the P-trap has dried out and sewer gas is rising through the drain. Run the water for 30 seconds to refill the trap. If the smell persists, there may be a crack in the pipe that needs professional inspection.

How do I clean out a bathtub drain?

Start by flushing with boiling water. If that does not shift it, pull out any visible hair with a drain snake or use a plunger. For stubborn blockages, professional drain cleaning is the safest way to clear it without damaging the pipe.

Why is my bathtub not draining at all?

A complete blockage is usually caused by a thick build-up of hair, soap scum, or product residue. Sometimes a blocked vent pipe or old plumbing is the culprit. If basic fixes do not work, a CCTV inspection will show exactly where the problem sits.

What does it mean if my shower drain smells like sewage?

Sewage smell means gas is getting past the seals in your plumbing. Could be a broken seal, a blocked vent, or a main line blockage. Get it looked at by a licensed plumber sooner rather than later to avoid damage or health risks.

Is it safe to use chemical drain cleaners?

Most off-the-shelf chemical cleaners are harsh on pipes and not great for the environment. For regular upkeep, enzyme-based cleaners work well without the risk. For a serious clog, call a plumber rather than reaching for the chemicals. You will save your pipes in the long run.

Shower drain smells but not clogged - what do I do?

If water drains fine but the smell persists, the problem is usually biofilm build-up, mould, or a dry P-trap. Clean the drain with a brush, spray with antimicrobial cleaner, and run the tap to refill the P-trap. If the smell returns within days, call a plumber to check for deeper issues.