Home > Why Your Shower Smells Like Sulfur and What It Reveals

Why Your Shower Smells Like Sulfur and What It Reveals

So your shower smells like rotten eggs. Don't panic! Here's the what, why, and how to fix it for good.
Disclaimer: The visuals and narratives here invite you to explore the invisible world of scent. They blend science, symbolism, and imagination, and should be understood as interpretive, not factual depictions of real places or events.

You step into the shower expecting a fresh start, but instead... eau de rotten eggs. It’s a common, nasty surprise. But that smell is actually a message from your pipes, and learning to decode it is the key to getting rid of it for good.

The Science Behind the Stench

Meet Hydrogen Sulfide

The culprit behind that rotten egg smell is a gas called hydrogen sulfide (H₂S). It's usually made by tiny organisms living in your pipes called sulfate-reducing bacteria, or SRB for short. 6 These ancient little critters have a very specific recipe for making a stink.

Diagram showing sulfate-reducing bacteria in a pipe's P-trap, consuming biofilm and releasing hydrogen sulfide gas.

For these bacteria to party, they need three things. First, sulfates, which are minerals naturally found in water. 8 Second, food... think soap scum, skin cells, body oils, and hair that form a slimy layer called biofilm. 10

Bacteria's Recipe for Stink: For hydrogen sulfide to be produced, three things are needed: 1) Sulfates (from water), 2) a food source (biofilm like soap and hair), and 3) an oxygen-free environment (like a P-trap).

The final ingredient is an oxygen-free zone. These bacteria hate fresh air and love stagnant, oxygen-poor spots like the water in a drain's P-trap or the sludge at the bottom of a hot water heater. 6 When all three conditions are met, the bacteria "breathe" sulfate and exhale stinky hydrogen sulfide gas.

This smell indicates a whole bacterial party is happening in your pipes. The SRB only move in after other germs have used up all the oxygen, creating the perfect home for them. 6 If you ignore it, you could get persistent slime, stubborn clogs, and even corroded pipes. 4

Playing Detective: Finding the Source

Okay, science lesson over. Time to find exactly where that smell is coming from. The fix depends entirely on the source, so you have to play plumbing detective.

Clue #1: The Smell is in One Drain

If the smell is coming from just one drain (like your shower) and happens with both hot and cold water, the problem is almost certainly biofilm in the P-trap. The P-trap is the U-shaped pipe under the drain. 10 It’s designed to hold water to block sewer gas, but it also traps a disgusting buffet of hair, soap, and gunk for bacteria to feast on. 3

A clear illustration of a sink or shower P-trap with a highlighted section showing the accumulation of hair, soap scum, and biofilm where water is held.

Clue #2: Only the Hot Water Stinks

If only the hot water stinks, no matter which faucet you use, your hot water heater is the prime suspect. 12 This happens at every hot water tap in the house. Inside most water heaters is a "sacrificial anode rod," usually made of magnesium or aluminum. 10

Cutaway view of a residential hot water heater, clearly showing the sacrificial anode rod inside the tank, with an arrow pointing to it and labeling it.

This rod corrodes on purpose so the steel tank doesn't rust. 16 But, this rod can react with sulfates in the water, creating that rotten egg gas. 4 The warm, sludgy bottom of the tank is the perfect incubator for this smelly reaction.

Clue #3: All Your Water Stinks

If all your water, hot and cold, at every single faucet, stinks... the problem is your water supply itself. This is most common for homes with a private well. 9 As groundwater trickles through the earth, it can pick up sulfur from rocks and soil. 8

Here's the definitive test: fill a glass with cold water and take it outside, away from any drains. If the water in the glass itself still smells, you've confirmed the issue starts at your source. 3

A person standing outdoors, away from their house, holding a clear glass of water and cautiously sniffing it to test for odors.

Sulfur vs. Sewer Gas

Wait, is it a rotten egg smell or just general sewer gas? They point to different problems. A rotten egg smell from a regularly used drain means you have a bacteria problem (biofilm).

A sewer smell coming from a guest bathroom that's rarely used probably means the water in the P-trap has just evaporated. 5 Run the water for a few minutes to refill it and the smell should go away. If you hear gurgling sounds along with the smell, you might have a blocked plumbing vent on your roof, which is a more serious issue. 10

Getting Rid of the Stink: The Fixes

Fixing a Smelly Drain

If the problem is biofilm in a drain, you need to clean it out. Start by pouring one cup of baking soda down the drain, followed by one cup of white vinegar. 21 It will fizz and bubble, which helps scrub the slime off the pipes.

A box of baking soda and a bottle of white vinegar next to a sink drain, with fizzing and bubbling shown coming up from the drain.

Let that mixture work for 15-30 minutes, then flush the drain with a gallon of boiling water. For tougher cases, or for regular maintenance, use a bio-enzyme drain cleaner. 5 It uses helpful bacteria to eat the gunk without using harsh chemicals that can damage your pipes.

Fixing a Smelly Water Heater

When the water heater is the culprit, you have a couple of options. A temporary fix is to flush the tank to remove smelly water and sediment. 4 You can also turn the thermostat up to 160°F (71°C) for several hours to kill the bacteria. (WARNING: This creates a serious scalding risk! Be very careful and always turn the temperature back down to a safe 120°F afterwards). 25

Safety Warning: Turning your water heater to 160°F (71°C) creates a serious risk of scalding. Use extreme caution and always remember to turn the temperature back down to a safe 120°F (49°C) after a few hours.

The real, long-term fix is to replace the anode rod. Have a qualified plumber swap the standard magnesium or aluminum rod with an aluminum/zinc alloy rod. 1 The zinc stops the chemical reaction that makes the stink without sacrificing the tank's protection. 16

This is a job for a professional. Seriously. It involves shutting off water and power, dealing with tank pressure, and needing special tools to remove the old rod. 4

Fixing a Smelly Water Supply

If your water source is the problem, you'll need a whole-house treatment system. The first step is to get your water professionally tested by a lab to see exactly what you're dealing with. 8

An infographic showing three types of whole-house water treatment systems: aeration, chlorination, and a large carbon filter.

An aeration system injects air into the water, which turns the smelly gas into solid particles that can be filtered out. 27 A chlorination system uses chlorine to kill the bacteria and is followed by a carbon filter to remove the chlorine taste. 29 For low levels of sulfur, a large whole-house activated carbon filter might be enough on its own. 8

What the Smell is Telling You

Your Plumbing's Health Report

A smelly drain is an early warning sign. That biofilm will eventually grow into a nasty, stubborn clog, so it’s a signal to clean your drain before you have a bigger problem. 8

A smelly water heater means the anode rod is doing its job, but it's reacting with your water and may be corroding quickly. It's a good reminder to get it inspected. Replacing a cheap rod can save you from buying an expensive new water heater. 16

It's a weird situation, the part protecting your tank is also causing the smell. Removing the rod is a terrible idea, it voids the warranty and your tank will rust out fast. 1 The smart move is to modify the protection by using a different kind of anode rod that protects without stinking.

Is It Dangerous?

Good news, probably not. Your nose is amazing at detecting hydrogen sulfide at incredibly low, non-harmful levels. 11 It’s officially a "nuisance contaminant," meaning it's annoying but the gas concentration is far too low to hurt you. 1

But... it does mean bacteria are growing in your water system, which is never ideal. If you're on a private well, it's a very good idea to get your water tested for other things like coliform bacteria and nitrates just to be safe. 8

A Message From Below

If the smell comes from your well water, it's a direct message from the earth under your house. It tells you about the local geology, and the rocks and soil your groundwater flows through. 8 In this case, the smell isn't a flaw in your plumbing, it's just a natural feature of your property.

Keeping the Stink Away for Good

To stop the smell from coming back, you need to be proactive. For drains, prevention is key. Once a week, pour boiling water down them to dissolve fresh soap scum. 34

Once a month, use the baking soda and vinegar trick or an enzyme cleaner to keep biofilm from growing. 35 Also, get a cheap mesh drain strainer. It'll catch hair and other gunk before it can become bacteria food. 2

A checklist graphic showing plumbing maintenance tasks: using a drain strainer, flushing the water heater, and testing well water.

For your hot water heater, flush it once a year to get rid of the sediment where bacteria love to grow (every six months if you have hard water). 37 This also improves the heater's efficiency. If you have a well, get your water tested every single year for bacteria and nitrates to catch any problems early. 41

Works cited

  1. marionhealth.org, https://marionhealth.org/wp-content/uploads/2023/11/Sulfur-well-water-H2S-Fact-Sheet-1.pdf
  2. What's Causing That Strong Rotten Egg Smell That's Coming From My Drain?, https://www.zoomdrain.com/blog/2022/march/whats-causing-that-strong-rotten-egg-smell-thats/
  3. Why Does My Bathroom Smell Like Sulfur? - Bluefrog Plumbing + Drain, https://bluefrogplumbing.com/why-does-my-bathroom-smell-like-sulfur/
  4. Why Does My Water Smell Like Rotten Eggs? Hydrogen Sulfide and ..., https://www.health.state.mn.us/communities/environment/water/wells/waterquality/hydrosulfide.html
  5. Why Does My Drain Smell Like Rotten Eggs? - Riteway AC, https://ritewayac.com/blog/why-does-my-drain-smell-like-rotten-eggs/
  6. Hydrogen Sulfide Sulfur Reducing Bacteria ... - KnowYourH2O, https://www.knowyourh2o.com/indoor-6/sulfate-reducing-bacteria
  7. Sulfate and Hydrogen Sulfide in Water - Ozone Solutions, https://ozonesolutions.com/blog/sulfate-and-hydrogen-sulfide-in-water/
  8. Hydrogen Sulfide in Drinking Water | Vermont Department of Health, https://www.healthvermont.gov/environment/drinking-water/hydrogen-sulfide-drinking-water
  9. What's the Deal with Smelly Well Water? - UNL Water, https://water.unl.edu/article/drinking-water-wells/whats-deal-smelly-well-water/
  10. Why Does My Shower Drain Smell Like Rotten Eggs? - This Old ..., https://www.thisoldhouse.com/plumbing/89938/shower-drain-smells-rotten-eggs
  11. Why Does My Bathroom Smell Like Rotten Eggs, Sulfur or Sewer? - Shilo Plumbing LLC, https://shiloplumbingllc.com/faq/why-does-my-bathroom-smell-like-sulfur/
  12. www.raynewater.com, https://www.raynewater.com/blog/how-to-get-rid-of-sulfur-smell-in-water/#:~:text=In%20general%2C%20there%20are%20two,specifically%20with%20the%20anode%20rod.
  13. well water facts odor staining.qxp_6-14 - Florida Department of Health, https://www.floridahealth.gov/environmental-health/private-well-testing/_documents/well-water-facts-odor-staining.pdf
  14. Why Does My Shower Drain Smell Like Rotten Eggs? - The Spruce, https://www.thespruce.com/shower-drain-smells-like-rotten-eggs-6832249
  15. How to Get Rid of a Sulfur Smell in Water | Aquasana, https://www.aquasana.com/info/sulfur-smell-in-water-pd.html
  16. A Guide to Sacrificial Anode Rods and Smelly Water | Bonney, https://www.bonney.com/blog/a-guide-to-sacrificial-anode-rods-and-smelly-water/
  17. Why Does My Hot Water Smell Like Eggs? | Anode Rods and Rotten Egg Odor - Vern Dale Water Experts, https://verndalewater.com/verndale-blog/why-does-my-hot-water-smell-like-eggs
  18. Solving rotten-egg odor in water heaters with aluminum/zinc ..., https://www.waterheaterrescue.com/troubleshooting/smelly-hot-water.html
  19. Sulfur Water Control (Rotten Egg Odor in Home Water Supplies) - Purdue Extension, https://www.extension.purdue.edu/extmedia/wq/wq-11.html
  20. How To Get Rid of Sulfur Smell in Water, https://www.raynewater.com/blog/how-to-get-rid-of-sulfur-smell-in-water/
  21. www.realsimple.com, https://www.realsimple.com/home-organizing/cleaning/cleaning-bathroom/how-to-clean-shower-drain#:~:text=Pour%201%20cup%20baking%20soda,flush%20with%20more%20hot%20water.
  22. 3 Easy Ways to Fix Smelly Shower Drains | Blockbusters, https://blockbusters.co.uk/blog/smelly-shower-drain/
  23. Drain preventive maintenance - DoItYourself.com Community Forums, https://www.doityourself.com/forum/toilets-sinks-showers-dishwashers-tubs-garbage-disposals/544802-drain-preventive-maintenance.html
  24. How To Prevent and Resolve Plumbing Sulfur Smells - This Old House, https://www.thisoldhouse.com/plumbing/21124404/how-to-prevent-plumbing-sulfur-smells
  25. Hydrogen Sulfide and Sulfur Bacteria in Well Water - Minnesota ..., https://www.health.state.mn.us/communities/environment/water/docs/wells/waterquality/hydrosulfide.pdf
  26. Sulfur Smell from hot water: replaced anode to aluminum, still smells after a month - Reddit, https://www.reddit.com/r/HomeImprovement/comments/kx9vyv/sulfur_smell_from_hot_water_replaced_anode_to/
  27. Aer-Max Aeration Systems – Pure Water Products, LLC, https://www.purewaterproducts.com/aer-max-aeration-systems
  28. REMOVAL OF HYDROGEN SULFIDE AND SULFATE - UGA, https://secure.caes.uga.edu/extension/publications/files/pdf/C%20858-15_2.PDF
  29. Sulfur Filter System | Chlorination Systems - Pentair, https://www.pentair.com/en-us/water-softening-filtration/whole-house/products/sulfur-filter-system.html
  30. Hydrogen Sulfide Removal – Pure Water Products, LLC, https://www.purewaterproducts.com/articles/hydrogen-sulfide
  31. Sulfate and Hydrogen Sulfide in Household Water, https://www.wellwater.bse.vt.edu/files/442-658.pdf
  32. Hydrogen Sulfide & Health - California Air Resources Board, https://ww2.arb.ca.gov/resources/hydrogen-sulfide-and-health
  33. I think I Smell Sewer Gas | Green River, WY, https://www.grwyo.org/450/I-think-I-Smell-Sewer-Gas
  34. How Often Should You Clean Shower Drains?, https://mainstreamhomeservices.com/blog/how-often-should-you-clean-shower-drains/
  35. Essential Drain Maintenance Checklist for Homeowners - americandreamsewer.com, https://americandreamsewer.com/preventative-maintenance-checklist-for-drains/
  36. How Often Should I Clean My Drains at Home? - Mr. Plumber - Indianapolis Plumbing Company, https://mrplumberindy.com/knowledge-center/how-often-should-i-clean-my-drains-at-home/
  37. How Often Should You Flush and Drain Your Water Heater? | Angi, https://www.angi.com/articles/how-often-should-i-flush-my-water-heater.htm
  38. A Practical Guide On How Often You Should Flush Your Water Heater | Bumble Breeze Plumbing, Heating & Air®, https://www.bumblebreeze.com/blog/a-practical-guide-on-how-often-you-should-flush-your-water-heater/
  39. How Often Should I Flush my Water Heater? - Wagner Mechanical, https://www.wagnermechanical.com/blog/water-heater-flush-guide
  40. How Often Does Your Water Heater Need to Be Flushed?, https://www.potterhvac.com/blog/plumbing-service/how-often-does-your-water-heater-need-to-be-flushed/
  41. Testing drinking water - Washington State Department of Ecology, https://ecology.wa.gov/water-shorelines/water-supply/wells/testing-drinking-water
  42. Guidelines for Testing Well Water | Drinking Water - CDC, https://www.cdc.gov/drinking-water/safety/guidelines-for-testing-well-water.html
  43. Well Water Testing - Illinois EPA, https://epa.illinois.gov/topics/drinking-water/private-well-users/well-water-testing.html
  44. What Causes a Sewer Smell in the Bathroom? - Make It Right® - Mike Holmes, https://makeitright.ca/holmes-advice/plumbing-water-quality/what-causes-a-sewer-smell-in-the-bathroom/