How to Remove Bathroom Drain Smell (Sink, Shower, and Tub)

A smelly bathroom drain is caused by organic biofilm — a layer of bacteria, hair, soap scum, and body oils coating the inside of the drain pipe. The smell is not from the sewer — it's from the buildup in the pipe itself. Here's how to eliminate it completely.

What You'll Need

• Zeiff Probiotic Enzyme Cleaner — the most effective solution for drain odors; digests the organic biofilm that causes the smell
• Baking soda and white vinegar
• JohnBee Spray Bottles
• Boiling water
• An old toothbrush (for cleaning the drain cover)

Why Bathroom Drains Smell

The smell comes from organic biofilm — a sticky layer of bacteria, soap scum, hair, and body oils that coats the inside of the drain pipe. As bacteria break down this organic matter, they produce hydrogen sulfide gas — the rotten egg smell. The biofilm can also accumulate on the drain cover, stopper, and the first few inches of pipe.

Step 1: Clean the Drain Cover and Stopper

1. Remove the drain cover or stopper.
2. Scrub with an old toothbrush and dish soap — remove all hair and soap scum.
3. Soak in white vinegar for 10 minutes.
4. Rinse and replace.

The drain cover and stopper are often the primary source of the smell — cleaning them alone sometimes resolves the odor.

Step 2: Baking Soda + Vinegar Flush

1. Pour ½ cup of baking soda down the drain.
2. Follow with ½ cup of white vinegar.
3. Cover the drain and let fizz for 15 minutes.
4. Flush with a full kettle of boiling water.

This breaks down surface biofilm and neutralizes odor-causing bacteria. Effective for mild to moderate drain odors.

Step 3: Enzyme Cleaner (For Persistent Odors)

1. Pour Zeiff enzyme cleaner down the drain according to directions.
2. Let sit overnight — don't run water for 6–8 hours.
3. Flush with warm water in the morning.
4. Repeat for 3–5 consecutive nights for persistent odors.

Enzyme cleaners are the most effective solution for drain odors because they digest the biofilm rather than just masking the smell. The probiotic bacteria in the cleaner continue working in the pipe for days after application.

How to Prevent Drain Odors Long-Term

• Do the baking soda + vinegar flush weekly
• Use enzyme cleaner monthly
• Install a drain strainer to catch hair before it enters the drain
• Clean the drain strainer after every shower
• Run hot water for 30 seconds after every shower to flush the drain

Frequently Asked Questions

Why does my bathroom drain smell like rotten eggs?

The rotten egg smell is hydrogen sulfide gas produced by bacteria breaking down organic matter in the drain. Enzyme cleaner eliminates the bacteria and the organic matter they feed on, removing the smell at the source.

Why does my bathroom smell like sewage?

If the smell is sewage (not just drain odor), the P-trap under the sink or shower may have dried out, allowing sewer gas to enter. Run water for 30 seconds to refill the P-trap. If the smell persists, there may be a plumbing issue requiring professional attention.

How long does it take enzyme cleaner to eliminate drain odors?

1–3 nights of treatment for moderate odors. For severe, long-standing biofilm buildup, 5–7 consecutive nights may be needed. The smell should reduce noticeably after the first treatment.