Why your water smells like rotten eggs

Find the source, then fix the drain, heater or well.

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Quick answer

Smell a glass of water in another room. No smell? It’s the drain. Hot only: the heater’s anode. Well water, hot and cold: groundwater. Gas in the air? Leave, call the gas company.

Hot-only fix I’d use: Corro-Protec powered anode$179.95 at AmazonPrice as of Oct 24, 2026, 5:30 AM EDT

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The finder leans on one split. Minnesota’s Department of Health says to smell the hot and cold taps after you’ve been away for a few hours. The smell builds up in still water, so the first run tells you the most.

Hot only points to the tank, since cold water never passes through it. Both points upstream, to the well, the main or a filter. A smell at one sink that isn’t in a glass points to the drain under that sink.

1. 1
   Pick the sink

   Use the sink where you notice the smell, before anyone has run water there for a while.

2. 2
   Fill a glass of cold

   Run the cold tap and fill a clean glass.

3. 3
   Walk away

   Take the glass to another room, away from any drain.

4. 4
   Smell the glass

   No smell in the glass, but a smell at the sink, means the drain is the source.

5. 5
   Repeat with hot

   Fill a second glass from the hot tap and smell it away from the sink too.

6. 6
   Try another sink

   If the glasses smell, check a tap on another floor to see if it’s the whole house.

Why the walk matters: drain gas is heavier than air and sits in the drain until running water pushes it out, the utility explains. Standing over the sink, you smell the drain and blame the water. In another room, the glass only smells of what’s in it.

Bradford White’s gas water heater manual says it plainly: the odorant added to natural gas and propane is what most people know as a sulfur or rotten egg smell. It also warns about odorant fade, where the smell weakens, so a faint whiff near a gas appliance still counts.

My call: if you can’t tell, treat it as gas. Leave, and call the gas company from outside or a neighbor’s phone, as Bradford White says. A false alarm costs you a visit. Guessing wrong costs a lot more.

Minnesota’s health department lists the same sources: decay and reactions with soil and rock, sulfur bacteria in the groundwater, well or plumbing, the water heater, and rarely pollution. USGS adds that the gas forms when groundwater filters through organic matter or minerals such as pyrite.

Signs that back up the smell: black stains on silverware and fixtures, and corroded metal parts. Slime that’s white, grey, black or reddish brown points to sulfur bacteria, the department says.

Most tank water heaters come with a magnesium anode rod that corrodes so the steel tank doesn’t. Penn State Extension explains that the magnesium can chemically reduce sulfate in the water to hydrogen sulfide. Rheem’s own manual says sulfate and the anode’s protection process can make a rotten egg odor in heated water.

That’s why a brand-new heater can start to smell. The water hasn’t changed; the rod has started working on it. Corro-Protec notes that many heater makers say softened water can wear a sacrificial rod faster.

Rheem is blunt about the last one. Its manual says not to remove the anode except to inspect or replace it, because running without it will greatly shorten the life of the glass-lined tank and will exclude warranty coverage. Penn State and Minnesota warn about the same trade.

My call: a powered anode is the fix I’d put in for good. It doesn’t dissolve, so there’s no rod to keep feeding the smell or to replace every few years. An aluminum rod costs less and works for many homes; it’s still a wear part.

Pulling the old rod is the hard part either way. Corro-Protec’s kit carries 1-1/16 in. and 1-3/16 in. sockets for common rod heads; add a breaker bar. The anode rod replacement guide walks through the swap. For rod lengths, threads and aluminum versus magnesium, see anode rod size and type.

Comparing powered anodes from different makers? The powered anode rod guide lines them up.

1. 1
   Cut the power or gas

   Turn the breaker off, or set a gas heater to pilot, before you open the tank.

2. 2
   Close the cold inlet

   Shut the valve on the cold line into the heater and open a hot tap to relieve pressure.

3. 3
   Drain a few gallons

   Drain enough that water won’t spill out of the anode port when the rod comes out.

4. 4
   Swap the rod

   Break the old rod loose, tape the new one’s threads and snug it in the same port.

5. 5
   Flush and refill

   Refill with a hot tap open until water runs steady, then restore power or gas.

6. 6
   Run the hot taps

   Run each hot tap for a few minutes; the old, smelly water has to clear out.

One warning from Rheem’s manual if the heater has sat for two weeks or more: hydrogen gas can build up in the tank, and it’s extremely flammable. Open the kitchen hot tap for several minutes before you use anything electric on the hot water, and keep any flame away. A sound like air escaping means gas was there.

Start with a safety test, not a filter. Minnesota’s health department says the smell usually isn’t a sign of unsafe water, but in rare cases it comes from sewage. To be safe, test the well for coliform bacteria and nitrate. The water test kit guide covers home kits and certified labs.

Penn State adds where it shows up most: wells drilled into acidic bedrock such as shale and sandstone. A softener can rarely host the bacteria too.

Hydrogen sulfide needs its own test at the tap. UGA Extension says it escapes from water so fast that it may be gone by the time a sample reaches a lab. Penn State says to test in the home, or have the lab stabilize the sample first.

That’s what the strips in the kit are for. The ITS 481167 reads 0 to 2 ppm in 20 seconds, and the ITS 481068 reads 5 to 80 ppm for strong wells. ITS says to test a fresh sample right away.

Penn State gives the details on chlorination: a small pump feeds chlorine into a tank or coil sized for at least 20 minutes of contact, and a carbon filter after it takes out leftover chlorine. It calls the upkeep significant: refilling, backwashing and replacing carbon.

My call: get the number before you buy anything. A carbon filter sold for a 5 mg/L well won’t keep up, and a chlorination system for 0.5 mg/L is more machine than you need. Filter picks for wells are in the well water filter guide and the iron filter guide.

If bacteria live in the well or pipes, shock chlorination comes first. Minnesota says sulfur bacteria are hard to remove once they’re established. Scrubbing the casing and special chemicals may be needed first, especially with iron bacteria, and that’s work for a licensed well contractor. For a softener or filter, ask its installer or maker how to disinfect it.

USGS suggests calling your local health department about an odor too, and testing at a state-certified lab if it doesn’t clear. A city supply is tested before it reaches you, so a house-wide smell that the utility can’t find usually points to something inside: a softener, a filter or the heater.

1. 1
   Pull the stopper

   Lift out the sink stopper and clean the gunk off it.

2. 2
   Fill with hot water

   Close the drain and fill the sink with hot water.

3. 3
   Add a little bleach

   Springfield Utility Board says a few ounces of chlorine bleach in the hot water.

4. 4
   Let it drain

   Pull the plug and let the hot, chlorinated water flush the drain.

5. 5
   Do the disposal

   Clean a kitchen disposal the same way, with the water running.

6. 6
   Check rarely used drains

   A floor drain or spare shower can dry out and let sewer gas in; run water in it.

Never mix bleach with a drain cleaner or vinegar; pick one and flush it through. If the smell comes from many drains at once or from the floor, it’s sewer gas, not a sink. That has its own causes, covered in sewer smell in the house. A smelly kitchen disposal has its own guide: garbage disposal smells.

Most people can smell hydrogen sulfide well below 0.5 mg/L, Penn State says, which is why it’s noticed long before it’s a health concern. The real cost is slower: black stains, tarnished silver and corroded fittings. UGA notes it can even react with a softener’s resin bed.

Best for a hot-only smell

Corro-Protec powered anode

$179.95 at Amazon

Check it on Amazon

Price as of Oct 24, 2026, 5:30 AM EDT

Best for pulling the old rod

Corro-Protec install kit

$24.95 at Amazon

Check it on Amazon

Price as of Oct 24, 2026, 5:30 AM EDT

Best for a faint smell

ITS 481167 strips

$16.72 at Amazon

Check it on Amazon

Price as of Oct 24, 2026, 5:30 AM EDT

Best for a strong well smell

ITS 481068 high range

$18.83 at Amazon

Check it on Amazon

Price as of Oct 24, 2026, 5:30 AM EDT

Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.

Smaller tank? The Corro-Protec 10–39 gallon model is the same titanium rod sized for smaller heaters. Corro-Protec says it works with city or well water, softeners and filters, and with electric, gas and hybrid tanks.

It draws less power than a night-light, about $3 a year, by Corro-Protec’s numbers. Leave it plugged in; protection pauses only while the power is out.

Swapping an anode is a fair job for a handy homeowner with a good socket and room above the heater. MDH suggests leaving it to a plumber unless you know your heater well, and I’d agree if the rod is old or the tank is in a tight closet. For a price range, try the plumbing cost estimator.

Sources

• Minnesota Department of Health, “Why does my water smell like rotten eggs? Hydrogen Sulfide and Sulfur Bacteria in Well Water” (health.state.mn.us, rev. 06/15/2023, read Oct 22, 2026).
• Penn State Extension, “Hydrogen Sulfide (Rotten Egg Odor) in Water Wells” (extension.psu.edu, updated Dec 10, 2024, read Oct 22, 2026).
• University of Georgia Cooperative Extension, Circular 858-8, “Your Household Water Quality: Hydrogen Sulfide and Sulfate” (read Oct 22, 2026).
• U.S. Geological Survey FAQ, “What can cause our water to have an earthy odor or to smell like rotten eggs?” (usgs.gov, read Oct 22, 2026).
• Springfield Utility Board, “Why does my water smell like rotten eggs or sewage?” (subutil.com, read Oct 22, 2026): drain gases and the glass test.
• Rheem, AP21980 Rev 02 electric residential water heater manual: anode rod, odor and hydrogen gas notices (read Oct 22, 2026).
• Bradford White, gas water heater manual 47150 rev A: gas odorant and odorant fade warning (read Oct 22, 2026).
• Corro-Protec FAQ, rotten egg smell page and warranty page (corroprotec.com, read Oct 22, 2026).
• Industrial Test Systems (SenSafe) product pages for WaterWorks hydrogen sulfide 481167 and high range 481068 (sensafe.com, read Oct 22, 2026).
• Part details for the Corro-Protec powered anodes and install kit and the ITS strips, read from Amazon’s product data on Oct 22, 2026.