Wondering where the smell comes from?
Where a rotten-egg smell comes from, in plain English
That rotten-egg smell is a gas called hydrogen sulfide. It can get into your water at a few spots on the way to the tap. Or it can come up out of the drain. Follow the water from where it comes in to where it goes out, and you can usually find the spot.
- The water coming in. Your water comes from a city main or a well. Some water carries the gas from the start, mostly well water. Then hot and cold both smell.
- The water softener, if you have one. Its tanks stay damp and dark inside. Once in a while, germs grow in there and make the smell. Penn State says that's rare.
- The water heater. A tank heater has a metal rod hanging inside that keeps the tank from rusting (the anode rod). Germs in the water react with it and make the gas. Then only the hot water smells.
- The faucet. Water that sits still in one faucet's pipe or filter can start to smell. Run it a few minutes, and it usually fades.
- The drain. Hair and gunk in a drain feed germs that smell like rotten eggs. Under every drain, a U-shaped bend (the trap) holds water that blocks sewer gas. If it dries out, the smell comes right up.
Air or water? Gas for your stove or furnace has no smell on its own. Gas companies add one that smells like rotten eggs, so you'll notice a leak. It hangs in the air, even when no water runs. Sulfur in water smells the same, but it comes out with the water. So it's strongest at a faucet or in a hot shower. A smelly drain smells at the sink, but a glass of the same water smells fine in another room. That's why the questions check the air first, then a glass of water away from the sink.
Whole house smells like a sewer, not just the water? See our guide to a house that smells like sewer. Water heater trouble too? See a water heater that's not making hot water or a water heater that's leaking. Washer smells too? See a washing machine that smells. Weak water too? See low water pressure.
Rather not do it yourself? Call a plumber.
That's a fine choice. Maybe you're busy. Maybe you're selling the house and just want it done right. A plumber can swap the rod in your water heater or find where the smell starts.
Most plumbers charge $45–$200 an hour, and some add a fee to come out.
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What to say
Calling a pro? Here's what to say.
A few lines to read when they pick up, and the questions to ask before anyone comes out.
Before you call
Say this
Hi. My water smells like rotten eggs. When's the soonest you can get here? And what's your fee for the visit? Does it go toward the repair?
Always ask
- What's your fee to come out, and does it go toward the repair?
- Do you charge by the job or by the hour?
- Will you tell me the full price before you start any work?
Watch out if
- They push a full replacement on the first visit for a small problem.
- They won't give you a price before starting.
- They add an emergency fee without telling you first.
Feeling pushed to decide on the spot? You can say no and hang up. You owe nothing for a phone call.
Answer up to 5 quick questions. We'll give you the words a pro uses.
Answer the questions →More of a list person?
Common symptoms, causes, tests and costs
Find the row that sounds like yours. The quick test is something you can do yourself in a few minutes.
| What you notice | What it probably is | Quick test | Do it yourself | With a pro | Verdict |
|---|---|---|---|---|---|
| Rotten-egg smell in the air, even with no water running, in a home with gas | You may have a gas leak | None. Leave the house | Pro job | $50–$250 | CALLSee the answer: You may have a gas leak |
| Rotten-egg or sewer smell in the air, and no gas in the home (or the gas company found nothing) | A smell from a drain or sewer pipe | Pour a gallon of water into drains you rarely use, then wait a day | Free | Not needed | FIXSee the answer: A smell from a drain or sewer pipe |
| The sink smells, but a glass of the water smells fine in another room | Germs in the drain, not the water | Smell a glass of the water in another room | Free | Not needed | FIXSee the answer: Germs in the drain, not the water |
| Only one faucet smells. The others are fine | Water sitting in one faucet's pipes or filter | Run that faucet 2 to 3 minutes. Does the smell fade? | Free | $45–$200 | FIXSee the answer: Water sitting in one faucet's pipes or filter |
| Only the hot water smells like rotten eggs. It's a tank water heater | The water heater is making the smell | Smell a glass of hot and a glass of cold water in another room | Pro job | $50–$350 | CALLSee the answer: The water heater is making the smell |
| Only the hot water smells. Can't find or safely reach the water heater, or you rent | Let a pro (or your landlord) take it from here | None. Hand it off | Pro job | $50–$150 | CALLSee the answer: Let a pro (or your landlord) take it from here |
| Hot and cold water both smell, on city water | Sulfur in the city water | Smell a glass of hot and a glass of cold water in another room | Pro job | $45–$200 | CALLSee the answer: Sulfur in the city water |
| Hot and cold water both smell, on a well | Sulfur gas in your well water | Smell a glass of hot and a glass of cold water. Then get a lab test | Pro job | $80–$4,000 | CALLSee the answer: Sulfur gas in your well water |
| Hot and cold both smell, and the smell fades with the softener on bypass | Germs growing in the water softener | Put the softener on bypass and smell a fresh glass of cold water | Free | $162–$983 | FIXSee the answer: Germs growing in the water softener |
2026 U.S. averages, rounded. Pro prices include parts and labor. Most plumbers charge $45–$200 an hour, and some add a fee to come out. Nights, weekends and big cities cost more. See all repair prices
Want proof it's the water?
The two-glass test
This tells you if the smell is in the drain, the hot water or all the water. San Jose Water and UGA Extension use the same idea.
- Run the cold water at the smelly sink for about 30 seconds. Fill a clean glass.
- Run the hot water until it's hot. Fill a second glass.
- Carry both glasses to another room, away from any sink or drain.
- Swirl each one and take a sniff.
- Neither glass smells: it's the drain. Clean the stopper and try bleach overnight.
- Only the hot glass smells: it's probably the water heater. Call a plumber.
- Both smell: it's the water itself, or a softener. Got a softener? Put it on bypass and try again. Then call the water company, or get the well tested.
- Only one faucet smells: run that faucet a few minutes and see if it fades.
Not sure it's safe?
Leave or stop right away if…
- You smell rotten eggs in the air, near the stove, furnace, water heater or dryer, even with no water running. Leave the house and call the gas company from outside.
- Your well water suddenly smells, tastes or looks different. Drink bottled water until it's tested.
- You're thinking of climbing into a well pit to look. Don't. The gas can build up in there.
- You're about to pour bleach into a drain that has drain cleaner in it. Never mix them.
- You're thinking of turning up the water heater to kill the smell. Don't. 160°F water can burn skin in about half a second.
A smell that only comes out with the water usually isn't an emergency. It can wait a day or two.
Got a big repair quote?
Repair, treat or replace?
Most rotten-egg water costs little to fix. A smelly drain is free. A new anode rod runs about $50–$350 (HomeAdvisor, HomeGuide). The big bill is a filter system for a well, about $1,000–$4,000 (HomeAdvisor). Ask yourself three things:
- Did you get the water tested? On a well, a lab test tells the pro which fix fits. Get the test before you buy a filter system.
- How old is the water heater? The date is on the sticker. A smell alone is usually a new rod, not a new water heater.
- Did shock chlorination wear off? Penn State says the smell often comes back after a well is shocked. If it keeps coming back, ask the pro about a filter system.
Example: $150 for a new rod on a 6-year-old water heater is in the normal range. A $4,000 filter system before anyone tests your well water is worth a second opinion.
Ran into a word you don't know?
Rotten-egg smell words, explained
Tap through these before you start. The drawings show roughly what each part looks like.
- Natural gas and propane
- Fuel for stoves, furnaces, water heaters and dryers. Gas companies add a rotten-egg smell to it, so you'll notice a leak.
- Gas meter
- The meter outside where gas comes into the house. If you have one, something in your home uses gas.
- Sewer gas
- Gas from the sewer pipes. It smells like rotten eggs or a dirty drain, and it shouldn't get into the house.
- Trap (P-trap)
- The U-shaped bend under a drain. The water it holds blocks sewer gas from coming up.
- Sink stopper
- The plug in a bathroom sink drain. Hair and gunk build up on it.
- Hydrogen sulfide
- The gas that makes water smell like rotten eggs. It's common in well water.
- Sulfur bacteria
- Germs that make hydrogen sulfide. They grow in wells, water heaters, softeners and drains. The pros call some of them sulfate-reducing bacteria.
- Water heater
- The tank or box that heats your home's water.
- Tankless water heater
- A water heater with no tank. It's a box on the wall that heats water as it flows through.
- Anode rod
- A metal rod inside a tank water heater that keeps the tank from rusting. With some water, it can make a rotten-egg smell.
- Aluminum/zinc anode rod
- A kind of anode rod that often helps with the smell. A plumber can swap one in.
- Powered anode rod
- A rod that uses a little electricity instead of metal wearing away. A.O. Smith sells one for smelly water.
- Faucet filter
- A filter on a faucet or under a sink that cleans the water. An old one can smell.
- Well
- A hole drilled into the ground that your water comes from, if you don't get a water bill.
- Pressure tank
- A round tank in the basement, garage or a closet on homes with a well. It keeps the water pressure steady.
- Shock chlorination
- Putting strong chlorine down a well to kill germs. The smell often comes back later.
- Coliform bacteria
- Germs a lab tests for to see if anything dirty, like sewage, is getting into a well.
- Water softener
- A tall, skinny tank next to a shorter tank of salt. It takes minerals out of the water.
- Bypass valve
- A knob, lever or button on the softener's pipes. On bypass, the water skips the softener.
- Brine well
- A tube inside the salt tank of some softeners. Some manuals say to pour bleach into it to sanitize.
- Regeneration
- When a softener cleans itself with salt water. Most start one on a timer, or with a button.
Still have questions?
Questions people ask most
Is water that smells like rotten eggs an emergency?
Water that smells like rotten eggs usually isn't an emergency, but a rotten-egg smell in the air is. If the house smells like rotten eggs near the stove, furnace or water heater, leave now. Call the gas company from outside. A smell that only comes out with the water can wait a day or two (Kansas Corporation Commission, Minnesota Department of Health).
Is it safe to drink water that smells like rotten eggs?
The gas that makes water smell like rotten eggs doesn't make people sick at the levels found in home water. Connecticut's health department says the gas alone "does not cause disease." It just tastes and smells bad (USGS, Penn State). On a well, get it tested for germs and nitrate. A new or sudden smell can come from sewage, so drink bottled water until you know (Minnesota Department of Health, UGA Extension). On city water, call your water company.
Is it safe to shower in water that smells like rotten eggs?
Yes, showering in water that smells like rotten eggs is safe for most homes, even though the smell is worst in a hot shower. Heat pushes the gas out of the water and into the air (Connecticut Department of Public Health). Run the bathroom fan. Only very high amounts of the gas in closed spaces, like a well pit, are dangerous (Minnesota Department of Health).
Why does my hot water smell like rotten eggs?
Hot water that smells like rotten eggs usually comes from the water heater. Germs in the water react with a metal rod inside the tank (the anode rod) and make the smell (Penn State, Minnesota Department of Health, Florida DOH). A plumber can swap the rod or clean the tank.
Why does my well water smell like rotten eggs?
Well water smells like rotten eggs when it carries a gas called hydrogen sulfide. Germs underground or in the well make it, and some rock adds to it (Penn State, Minnesota Department of Health). A sudden change is worth a water test right away. The CDC says to test when the taste, color or smell changes.
Why does my house smell like rotten eggs?
A house that smells like rotten eggs may have a gas leak, so leave first and call the gas company from outside. No gas in the home, or the gas company found nothing? It may be sewer gas from a drain. Our guide to a house that smells like sewer walks you through it. If the smell only comes out with the water, use the questions above.
Why does my water smell like rotten eggs at only one faucet?
A smell at just one faucet usually comes from that drain, not the water. Fill a glass there and smell it in another room. If the glass smells fine, clean the drain (UGA Extension, San Jose Water). If the glass smells too, run that faucet a few minutes. Water that sat in the pipe can smell until it clears (Florida DOH).
Why does my water smell like rotten eggs after vacation?
Water that sat still for a while is more likely to smell, because the germs that make the gas grow best in still water (State Bulletin 22). Run each faucet for a few minutes. Gone for 2 weeks or more? Bradford White says hydrogen gas can build up in a water heater. Open the kitchen hot water for several minutes first, with no flame or cigarette nearby. Still smells after that? Use the questions above.
How do I get rid of the rotten egg smell in my hot water?
The fix for a smelly water heater is a new metal rod and a cleaned-out tank, and a plumber does both. The rod can be aluminum/zinc or a powered one (Minnesota Department of Health, Penn State). Don't take the rod out, and don't turn the heater way up to kill the germs yourself. A.O. Smith's chart shows 160°F water can burn skin in about half a second.
Can a water softener make water smell like rotten eggs?
Yes, a water softener can make water smell like rotten eggs when germs grow inside it, though Penn State says that's rare. Put it on bypass and smell the cold water. If the smell goes away, sanitize the softener the way the manual says (GE), or call the company that put it in. Softened water can also make a tank water heater smell (State Bulletin 22).
How much does it cost to fix water that smells like rotten eggs?
Fixing rotten-egg water costs nothing for a smelly drain, and about $50–$350 for a new water heater rod. That's what HomeAdvisor ($50–$150) and HomeGuide ($150–$350) list for a plumber to do it. A lab water test is about $100–$500 (Angi). A filter system for a well is about $1,000–$4,000 (HomeAdvisor).
Who do I call when my water smells like rotten eggs?
Call a plumber when only the hot water smells, and your water company when both hot and cold smell on city water. On a well, call your county health department for a test, then a well or water treatment company. Smell rotten eggs in the air? Call the gas company from outside. Try the free glass test first. Renters should call their landlord.
How we built this
The questions follow the order a plumber checks a rotten-egg smell: the air first (for gas), then a glass of hot and cold water away from the sink, the water heater, where the water comes from, and the softener. Each answer makes some causes more likely and others less likely.
Prices are 2026 national averages from published repair-cost guides, rounded. Your local prices will differ.
- Minnesota Department of Health, hydrogen sulfide and sulfur bacteria in well water (October 2024)
- Connecticut Department of Public Health, hydrogen sulfide and sulfate in private drinking water wells (July 2026)
- Penn State Extension, hydrogen sulfide (rotten egg odor) in water wells (December 2024)
- U.S. Geological Survey, why does my water smell like rotten eggs? (June 2019)
- University of Georgia Extension, odors in your water, Circular 1016 (reviewed October 2024)
- Florida Department of Health, well water facts: odor and staining (read October 2026)
- CDC, guidelines for testing well water (July 2024)
- San Jose Water, what does your water smell or taste like? (read October 2026)
- A.O. Smith, residential gas water heater owner's manual, part 184707-001 (read October 2026)
- State Water Heaters (A.O. Smith), Bulletin 22, smelly water (read October 2026)
- Rheem, electric water heater use and care manual, anode rod page (read October 2026)
- Rheem, 5 signs your water heater is going bad (December 2025)
- Bradford White, installation and operation manual, 238-44422-00Y (February 2022)
- A.O. Smith Product Preservers powered anode rod, product description at SupplyHouse (read October 2026)
- GE water softener owner's manual, GXSF27B, sanitizing (read October 2026)
- HomeTips, water heater smells like rotten eggs (read October 2026)
- Kansas Corporation Commission, natural gas safety (read October 2026)
- Health Canada, never mix bleach with other cleaning products (December 2021)
- Sears Home Services, why does my laundry room smell (June 2026)
- HomeAdvisor, water heater repair cost (June 2026)
- HomeGuide, water heater repair cost (August 2025)
- Fixr, water heater repair cost (August 2025)
- HomeAdvisor, cost to hire a plumber (June 2026)
- HomeGuide, drain cleaning cost (December 2025)
- HomeAdvisor, home water filtration system cost (June 2026)
- HomeAdvisor, water softener repair cost (June 2026)
- Angi, how much does it cost to shock a well? (July 2026)
- Bob Vila, home water filtration system cost (August 2022)
- ConsumerAffairs, cost to repair frozen pipes, with plumber rates (June 2026)
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