Most Likely Causes (Ranked)
Hair accumulates in the drain over weeks, catching soap, conditioner, body oils, and dead skin. Bacteria colonize this organic mass, creating a slimy biofilm that produces foul-smelling compounds. The clog may not be large enough to slow drainage noticeably but is plenty to produce odor.
Even without a hair clog, soap scum and body oils coat the inside of the drain pipe and P-trap over time. This greasy layer supports bacterial growth that produces persistent odor.
If the shower isn't used for 2-4 weeks, the P-trap water evaporates and sewer gas enters the bathroom.
A cracked P-trap, loose connection, or improperly installed drain can allow sewer gas to bypass the water seal.
How to Fix It
Remove Hair Clog
$0-5Takes 5 minutes, fixes the most common cause.
- 1Remove the drain cover (usually unscrews or pops off).
- 2Use a Zip-It drain cleaning tool ($3-5) or bent wire hanger to fish out the hair clog. Pull slowly — it may be longer than you expect.
- 3Dispose of the hair mass (don't flush it). Rinse the drain opening.
- 4Pour 1/2 cup baking soda down the drain, wait 15 minutes, then pour 1 cup white vinegar. Cover the drain and wait 30 minutes.
- 5Flush with hot water for 2 minutes.
Deep Clean the Drain
$0-10For biofilm that remains after removing hair.
- 1Pour a pot of boiling water down the drain slowly.
- 2Follow with 1/2 cup baking soda, then 1 cup vinegar. The fizzing action breaks up biofilm on pipe walls.
- 3After 30 minutes, flush again with boiling water.
- 4For persistent biofilm: use enzyme drain cleaner (Bio-Clean, $10-15) poured in before bed. Enzymes digest organic buildup overnight.
- 5Never use chemical drain cleaners for odor — they damage pipes and don't address the biofilm.
Install a Drain Hair Catcher
$5-12Prevention is better than monthly clog removal.
- 1Install a silicone or stainless steel drain hair catcher ($5-12). TubShroom and OXO make popular options.
- 2Clean the hair catcher after every shower — just wipe off the collected hair.
- 3This single $5 investment prevents virtually all hair-related drain odor and clogs.
When to Call a Professional
sewer smell persists after cleaning and the shower is used regularly — possible vent pipe issue or damaged P-trap.
Drain is very slow even after clearing hair — may have a deeper clog that needs professional snaking ($100-250).
Multiple bathroom drains smell — suggests a vent pipe blockage affecting the whole bathroom.
How to Prevent It
Use a drain hair catcher — the #1 prevention tool ($5-12).
Monthly enzyme treatment — prevents biofilm between deep cleans.
Run hot water for 1 minute after each shower — helps flush soap scum and oils.
Run water in unused showers monthly — keeps P-trap full.
The $5 Fix That Prevents 90% of Shower Drain Problems
A drain hair catcher (TubShroom, $10-12, or basic silicone version, $5) sits in or over the drain and catches hair before it enters the pipe. It's the single most effective prevention for shower drain smell and clogs.
Without a catcher, hair accumulates in the drain pipe over weeks, creating the organic mass that bacteria colonize. With a catcher, you remove hair after each shower and the pipe stays clean. It's that simple.
Frequently Asked Questions
Remove the drain cover and use a Zip-It tool ($3) or bent wire hanger to pull out the clog. For deeper clogs, a small drain snake ($10-15) reaches further. Chemical drain cleaners are not recommended — they damage pipes and don't prevent recurrence.
rotten egg smell is hydrogen sulfide produced by bacteria in the drain biofilm or from sewer gas through a depleted P-trap. Clear any hair clog, flush with baking soda + vinegar, and ensure the P-trap has water. If it persists, the vent pipe may be blocked.
Remove visible hair weekly (or use a hair catcher). Do the baking soda + vinegar deep clean monthly. Use enzyme drain cleaner quarterly for maintenance.
The smell itself (hydrogen sulfide, biofilm VOCs) at household concentrations is unpleasant but not dangerous. However, sewer gas at high concentrations can cause headaches. If the smell is very strong and sewer-like, fix it promptly.