Rotten-egg smell in your water
Find the source of the smell before you buy a filter
Hydrogen sulfide can come from the well, from bacteria, or from your water heater. Each has a different fix, and the cheapest one is often the right one.
Smell check
Answer four questions. Run a hot tap and a cold tap for a minute each, and smell the water in a glass away from the sink.
Which fix fits which level
If the smell is in hot and cold water from a well, the hydrogen sulfide level decides the equipment. Test it on site, because the gas escapes from a sample bottle within hours.
| Hydrogen sulfide | What it’s like | Usual fix |
|---|---|---|
| Under about 1 mg/L | Faint smell | Activated carbon can work, but it loads up quickly. An air-injection filter lasts longer. |
| 1 to 8 mg/L | Strong smell | An air-injection oxidizing filter. Single-tank systems are commonly rated up to about 8 mg/L. |
| Above 8 mg/L | Overpowering | Chlorine or hydrogen peroxide injection, a contact tank, then a backwashing filter. |
Sulfur water guides
All guides →- Why your water smells like rotten eggsRotten-egg water means hydrogen sulfide. Where you smell it points to the water heater, the well, bacteria or a drain. Find the cause before buying a filter.
- Hot water smells like rotten eggsIf only your hot water smells like rotten eggs, the water heater is the cause. How to confirm it, swap the anode, flush the tank, and why a filter won't help.
- Is sulfur water safe?Rotten-egg water is usually a nuisance, not a health risk. When the smell can signal contamination, what the gas does in the air, and what to test first.
- How to test for hydrogen sulfideHydrogen sulfide escapes from a sample fast, so testing takes care. The free smell test, lab vs on-site kits, what to ask for, and what your result means.
- Types of sulfur water filtersCarbon, aeration, air-injection, greensand and chemical injection compared by hydrogen sulfide level in mg/L, with where extension sources disagree.
- Air-injection sulfur filtersHow an air-injection oxidizing filter removes hydrogen sulfide without chemicals, what levels it handles, install needs, upkeep, and when chlorine fits better.
- Chlorine injection for sulfur waterWhen chlorine injection is the right fix for rotten-egg well water, how much chlorine it takes, contact tank sizing, carbon after, and the upkeep involved.
- Hydrogen peroxide for sulfur waterPeroxide injection oxidizes hydrogen sulfide without chlorine, but household guidance is thin. What sources say, how it compares, safety, and dealer questions.
- Shock chlorinate for sulfur bacteriaIf your well's rotten-egg smell started suddenly or fades as the tap runs, sulfur bacteria are likely. How much bleach, contact time, flushing and retesting.
- Sulfur and iron in well waterRotten-egg smell plus orange or black stains means hydrogen sulfide and iron together. How to test, which systems treat both, and the order of treatment.
- Sulfur smell in city waterCity water that smells like rotten eggs usually picks it up in your home, from the water heater or a drain. How to tell, and when to call the utility.
- Sulfate vs hydrogen sulfideSulfate is a dissolved mineral; hydrogen sulfide is the rotten-egg gas. How they differ in smell, health, testing and treatment, and how one becomes the other.
- Sulfur water filter costTypical 2026 costs to fix rotten-egg water, from a free smell test and an anode rod to air-injection and chlorine systems, plus running costs and extras.
Reviews
Other well water problems, such as iron, hardness, bacteria or nitrate? See Well Water Filter Systems.
Common questions
Why does my water smell like rotten eggs?
The smell is hydrogen sulfide gas. It comes from the groundwater itself, from sulfur bacteria in the well or plumbing, or from the magnesium anode rod in a water heater reacting with sulfate in the water. Where you smell it tells you which.
Why does only my hot water smell like rotten eggs?
Hot-water-only smell almost always starts in the water heater. Bacteria react with the magnesium anode rod and produce hydrogen sulfide. Swapping in an aluminum-zinc or powered anode usually fixes it without any filter.
Is it safe to drink water that smells like sulfur?
Hydrogen sulfide at the levels found in household water is usually a nuisance rather than a health risk, and you can smell it long before it reaches harmful levels. It is still worth testing for bacteria, because sulfur bacteria can point to a well that lets surface water in.
What is the best filter for sulfur smell in well water?
It depends on the level. Low levels can be handled by carbon, moderate levels by an air-injection oxidizing filter, and high levels by chlorine or hydrogen peroxide injection followed by a filter. Test hydrogen sulfide on site first, because it escapes from a sample bottle quickly.