Does a Water Softener Remove Sulfur Smell? (The Honest Answer)
Number copied. Text it from your phone: 443-277-2204.
No. A water softener does not take out a rotten egg smell. If the smell was in your water before the softener went in, it is still there after. The smell is hydrogen sulfide, a gas, and a softener is built to take out hardness. What takes the smell out is an iron and sulfur filter ahead of the softener.
A softener can still be part of the story in two cases: the smell started after a softener went in, or only the hot water smells. Each has its own fix, and neither one is a new softener. Both are covered in when the smell starts after the softener.
If your water is also hard, the softener still has a job: once the filter has taken out the smell and the iron, it takes out the hardness. Before you buy anything, smell the cold and the hot water separately. That one test tells you where the smell comes from.
Quick Answer
A water softener does not remove a sulfur or rotten egg smell. An iron and sulfur filter ahead of the softener does.
- A softener removes hardness, not gas. Ion exchange resin swaps calcium and magnesium for sodium. Hydrogen sulfide (the rotten egg smell) is a dissolved gas, not a hardness mineral, so the resin does not touch it. See why a softener cannot remove the smell.
- Sulfur can damage the softener. High levels of hydrogen sulfide can foul the resin, and iron that has turned to rust fouls it too.
- What takes the smell out. For a rotten egg smell (1 to 10 ppm), an air-injection iron and sulfur filter, with no chemicals, ahead of the softener. For a light smell under about 1 ppm, a carbon tank after the softener. See what removes the smell.
- Only the hot water smells? That is usually the water heater's anode rod, and a softener makes it more likely. A plumber swaps the rod.
- The smell started after the softener? If the cold water smells only when it runs through the softener, bacteria may be growing in it, and the softener gets sanitized with bleach. See when the smell starts after the softener.
Prices: our sulfur filters run $2,095 to $3,295, and a filter and softener together start at $3,395.
What's in This Guide
What a water softener actually does
A water softener takes out hardness: the calcium and magnesium that leave scale in pipes and water heaters and spots on glasses. Its resin swaps the calcium and magnesium for sodium. When the resin is full, the softener rinses it with salty water (brine) from the salt tank and starts over.
That is the whole job. There is no air in the tank, nothing in it that reacts with a gas, and nothing in the cycle that rinses sulfur down the drain.
Why a softener cannot remove rotten egg smell
The rotten egg smell is a gas, hydrogen sulfide, and a softener cannot take a gas out of water. I go through it in my sulfur filter video, starting at 2:44:
What I say there: "If you're using a water softener to remove iron itself, it's not gonna remove the sulfur. The sulfur's still gonna be there."
A caller last August had the smell in both the hot and the cold water, with a softener already in. I told him the softener doesn't take that out: "the softener is loading up with sulfur, and it can't regenerate and backwash it out, and it's just holding it."
The sulfur can also hurt the softener. The Connecticut Department of Public Health says high levels of hydrogen sulfide can foul the resin bed of a softener, and the University of Georgia says high levels can adversely affect one. Iron is the other problem: Penn State Extension says iron that has already turned to rust fouls softener resin.
What actually removes sulfur smell
The fix depends on how strong the smell is. Carbon handles a light smell, an air-injection filter handles a rotten egg smell, and above 10 ppm it takes chlorine or peroxide. The level comes from a lab test, in ppm (parts per million).
| Hydrogen sulfide level | What it smells like | What takes it out |
|---|---|---|
| Under about 1 ppm | A musty or swampy smell | A carbon tank, which wears out sooner on sulfur |
| 1 to 10 ppm | Rotten eggs | An air-injection iron and sulfur filter, with no chemicals |
| Above 10 ppm | Most wells are not this high | Chlorine or peroxide fed into the water, then filtered |
For a light smell, the carbon tank is the Clack 2.5 non-backwashing carbon filter ($1,695). For a rotten egg smell, it is the air-injection filter. What your hydrogen sulfide level means goes through each level.
The air pocket at the top of the tank turns the gas into solid specks. The Katalox Light below catches them, along with iron and manganese, and the tank rinses what it caught down the drain. It ships set to rinse every day, and it can be set to rinse less often. Every size is rated for up to 10 ppm of hydrogen sulfide, 30 ppm of iron and 15 ppm of manganese; the four sizes are on sulfur filters for well water.
The filter works best near pH 8. If yours is lower, send me your test before you order. If your pH is low, an acid neutralizer goes in too, and I set its place from your test.
What ships: the tank (empty), the new Fleck 2510 AiQ control valve with its bypass valve, a fill funnel, and the Katalox Light in separate bags or boxes, which is loaded into the tank at install. Drain tubing is not included; your plumber sizes it. We recommend a licensed plumber for the install, and I support your plumber by phone at 800-460-5810.
Get the level before you pick one. The gas escapes from an ordinary mailed bottle, so the $139 hydrogen sulfide test preserves the sample when you take it and reports the level and the pH, usually in about 10 business days. The $199 well water test covers hardness, iron and pH, but not hydrogen sulfide.
What buyers noticed about the smell
These are verified purchases of our air-injection filter or its valve, newest first.
| Buyer | What they bought | What they wrote |
|---|---|---|
| Keith S., Jul 2026 Verified buyer | 2.5 cubic foot iron and sulfur filter | "We see, feel and smell the difference that night." |
| A buyer, Dec 2025 Verified buyer | 2.5 cubic foot iron and sulfur filter | "The filter works as advertised - immediately noticed vast improvement of smell/taste of water." |
| James C., Mar 2020 Verified buyer | Fleck 2510AIO air-injection valve | "Works very well taking iron and rotten egg smell from the well water." |
Hard water with a sulfur smell
You need both. Put the iron and sulfur filter before the softener. That way the softener gets water that is already free of the smell and the iron.
| Step | Equipment | Why this spot |
|---|---|---|
| 1 | Well tank | Put every filter after this tank |
| 2 | Sediment filter, 5 micron cartridge | Catches sand and grit first |
| 3 | Iron and sulfur filter | Takes out the smell, iron and manganese |
| 4 | Water softener | Takes out hardness after the smell is gone |
| 5 | Carbon tank, if you want one | Cleans up anything left over in the water |
| 6 | UV light, if you have bacteria | Goes last, after the water is clean |
That is the setup I lay out in the sulfur filter video: a Big Blue first, the 2.5 cubic foot air-injection filter next, a 64,000 grain softener, a carbon tank after the softener, and a UV light last. The correct order for well water treatment goes through every stage.
A caller who had settled on the filter asked me, "So basically all I need is that and then a water softener if I need that too, right?" Yes, and if you order both, the package costs less: the 1.5 cubic foot filter with a Fleck 5600SXT 48,000 grain softener is $3,395, and the 2.5 with a 64,000 grain is $3,995 (iron filter and softener packages). What size water softener covers the softener side.
We recommend a licensed plumber for the install. For a filter and a softener together, I tell callers it shouldn't be more than $700 to $1,000, and about 3 or 4 hours at the most.
When the smell starts after the softener
If the smell started after a softener went in, test the softener first. Put the softener in bypass and smell the cold water. If the smell goes away, the softener is the source. If it is still there with the softener in bypass, the softener is not the source.
The bypass sits on the back of the softener's valve, where your pipes connect, and it lets the water go around the softener. Smell the cold and the hot separately, after the water has sat in the pipes for a few hours. Then match what you found:
| Where you smell it | What it usually means | What to do |
|---|---|---|
| Hot and cold, even with the softener bypassed | Sulfur gas in the well water | An iron and sulfur filter ahead of the softener |
| Only in water that runs through the softener | Sulfur bacteria growing in the softener | Sanitize the softener with bleach |
| Only the hot water | The rod inside the water heater (the anode) | A plumber replaces the rod and chlorinates the tank |
| One sink only | The drain under that sink | Clean the stopper and flush the drain |
Bacteria growing in the softener
The Vermont Department of Health says a smell that comes only from water treated by the softener, and not from untreated water, is likely sulfur bacteria in the softener. Penn State Extension calls it rare. The University of Georgia says these bacteria leave a black slime inside the unit.
The Minnesota Department of Health says to get disinfection instructions from the maker. For the Fleck softeners we sell, Pentair's are: plain 5.25% household bleach, 1.2 fluid ounces per cubic foot of resin, poured into the brine well of the salt tank after a backwash, then a normal regeneration. That is about 1.8 ounces for the 1.5 cubic feet of resin in our 48,000 grain. Water smells after the softener has the full steps.
A smell only in the hot water
The University of Georgia explains how a softener makes this more likely: softened water is more corrosive, so the water heater's magnesium rod (the anode) dissolves faster, and the dissolved magnesium feeds the bacteria that make the gas. A.O. Smith, the water heater maker, lists water softeners first among the things that raise the odds. The fix is at the heater, not the softener: a plumber replaces the rod with an aluminum or zinc one, then chlorinates the tank. Hot water smells like rotten eggs goes through it.
A smell at one sink only is usually that sink's drain. Rotten egg smell in well water covers the drain cleaning.
Text me which faucets smell
Text me whether the cold, the hot or both smell, whether you have a softener, and your test numbers if you have them. I will tell you what to fix first.
8 AM to 5 PM Eastern, seven days a week. A real person, not a call center.Frequently asked questions
Is it safe to drink water that has a sulfur smell?
In the water, at the levels you can smell, hydrogen sulfide is a nuisance, not a health threat, and there is no drinking water standard for it. In most cases the smell has nothing to do with whether the water is sanitary, but test for coliform bacteria and nitrate to be safe. Is water that smells like eggs safe has more.
Can I shower if my water smells like sulfur?
The water itself is an odor problem at the levels you can smell, not a health one. The gas in the shower air is where to be careful: Washington's Department of Health lists eye, nose and throat irritation even at levels that smell like rotten eggs, and harder breathing for people with asthma. Run the bathroom fan or open a window.
Can hard water smell like sulfur?
Hardness itself has no smell. A well can be hard and also carry hydrogen sulfide, and then it needs both a filter and a softener. When only the hot water smells, the Minnesota Department of Health explains that the water heater's magnesium rod can turn sulfate in the water into hydrogen sulfide.
What could be causing a rotten egg smell in my house?
If the smell comes with the water, it is hydrogen sulfide from the well, the water heater or one drain. If you smell rotten eggs in the air with no water running, treat it as a possible gas leak: gas companies add a rotten egg odorant to natural gas. NW Natural, a gas utility, says to leave right away, even if the smell seems mild, and then call your gas company.
Aidan Walsh
Co-owner & Residential Water Treatment Specialist, Mid Atlantic WaterAidan Walsh has spent 32 years in residential water treatment, the first stretch of it installing and servicing well systems before Mid Atlantic Water became an online supplier. Mid Atlantic Water is a family company; every recommendation on this site is based on what actually failed in the field and what fixed it. If you have a question this page did not answer, call 800-460-5810 or text him at 443-277-2204.
Aidan answers calls and texts 8 AM to 5 PM Eastern, every day.Number copied. Text it from your phone: 443-277-2204.