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Last updated: February 27, 2026

How to Remove Hydrogen Sulfide from Well Water

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The first question to answer isn’t what product to buy. It’s which tap smells.

That one question narrows the cause from a dozen possibilities to one or two. And the cause determines the fix. Treating a water heater problem the same way as a well problem wastes money and doesn’t solve anything.

Step 1: Identify the Source

Only the hot water smells. The cause is almost certainly your water heater, not your well or your plumbing. Magnesium anode rods in standard tank heaters react with sulfate in water to produce hydrogen sulfide gas inside the tank. Cold water doesn’t pass through the tank, so it doesn’t smell. Hot water does.

This is a heater maintenance issue, not a water quality issue.

Both hot and cold water smell. The source is in your water supply, either from the well itself or from hydrogen sulfide gas naturally dissolved in the groundwater.

The smell is only at some taps, not all. Check for a pattern. If one sink smells but others don’t, the issue may be in a section of pipe or in a specific fixture. This is unusual and worth inspecting physically.

Fixing the Water Heater Source

If only your hot water smells, replace the magnesium anode rod with an aluminum/zinc combination anode. This is a straightforward water heater maintenance task that most homeowners can do in 30-60 minutes.

Turn off the water heater and cold water supply. Find the anode rod, usually a hex plug on top of the heater, sometimes under the decorative cover. Drain a few gallons to reduce pressure. Unscrew the existing rod and replace it with an aluminum/zinc combination rod (available at hardware stores and online for $20-40). Refill and restart the heater.

The sulfur smell should disappear from your hot water within a day. If it persists, your well water itself may also have some dissolved H2S, which the fix above won’t address entirely.

A powered (impressed current) anode is another option, especially for heaters with very active sulfate chemistry. These run on low-voltage electricity and eliminate the anode-reaction issue permanently. Cost is higher ($100-200) but requires no replacement cycle.

Step 2: Test the Concentration (For Well Sources)

If both hot and cold water smell, test your well water for hydrogen sulfide concentration. Many standard well water tests don’t include H2S, so request it specifically. H2S is volatile, so samples must be analyzed quickly or preserved immediately, follow your lab’s collection instructions carefully.

Knowing your concentration determines which treatment approach is right:

  • Below 0.1 mg/L: Low level. Carbon filtration is often adequate.
  • 0.1 to 2 mg/L: Moderate. Aeration or continuous chlorination works well.
  • Above 2 mg/L: High. Continuous chlorination is the primary approach.

If you also have iron bacteria in your well (orange-brown slime in the toilet tank), the sulfur smell may be coming from those bacteria rather than from geological H2S. Shock chlorination is the first step when bacteria are confirmed. See how to shock chlorinate a well for the procedure.

For testing options, see best mail-in water tests.

Step 3: Choose the Right Treatment

Low Levels (Below 0.1 mg/L): Carbon Filtration

Activated carbon, whether in a whole-house filter or a point-of-use filter under the sink, adsorbs hydrogen sulfide at low concentrations. This is the simplest solution and works for mild odor problems.

A whole-house carbon block filter ahead of the pressure tank treats all water entering the home. Most carbon filters need replacement every 6-12 months depending on your water’s H2S load and flow volume.

Point-of-use carbon filters (under-sink or countertop) treat drinking and cooking water only. If you also notice the smell in showers, a whole-house unit makes more sense.

Moderate Levels (0.1 to 2 mg/L): Aeration

Aeration physically strips dissolved hydrogen sulfide gas from water by exposing it to air before it enters your home’s plumbing. Since H2S is a gas dissolved in water, it off-gasses readily when water is agitated or sprayed.

Air injection systems inject a pocket of air into the water stream ahead of the pressure tank. The water and air mix, the H2S transfers into the air, and the gas is then vented out. These whole-house systems run automatically and don’t require chemicals. Removal rates of 70-95% are typical for moderate H2S levels.

Backwash aeration filters (also called oxidizing filters or air injection systems) combine aeration with a filtration media that traps any oxidized sulfur particles. They’re well-suited for water that has both H2S and dissolved iron, since the oxidation process handles both simultaneously.

Aeration systems require professional installation and sizing based on your flow rate and H2S level. Costs typically run $800-1,500 installed.

High Levels (Above 2 mg/L) or Bacterial Source: Chlorination + Carbon

At high H2S concentrations, or when iron bacteria are contributing to the odor, continuous chlorination is the most reliable approach.

A chemical feed pump injects a dilute bleach solution (sodium hypochlorite) into the water line ahead of a contact tank. The chlorine oxidizes the hydrogen sulfide into elemental sulfur, which precipitates as a solid. The water then passes through a carbon filter to remove residual chlorine and any remaining odor compounds.

This system requires:

  • A chemical feed pump (approximately $150-400)
  • A contact tank (30-60 minutes of contact time)
  • A backwash filter to remove precipitated sulfur
  • A carbon post-filter to remove residual chlorine

Total installed cost typically runs $1,200-2,500 depending on flow rate and components. It’s more complex than aeration but handles higher concentrations reliably and eliminates iron bacteria at the same time.

The chlorine dose needs periodic adjustment as your H2S levels change seasonally. A simple chlorine test at a tap can confirm the system is dosing correctly.

Monitoring After Treatment

Run a follow-up H2S test 30-60 days after installing any treatment system. Well water chemistry can change, and confirming the system is performing as expected is worth the cost of one test.

For whole-house aeration and chlorination systems, schedule annual service to inspect the media, check pump calibration, and verify filter performance.

What Doesn’t Work

Boiling: H2S is volatile and partially escapes when water boils with the lid off, but this isn’t a practical treatment. It doesn’t address the problem at scale and doesn’t treat shower water.

Pitcher filters at high concentrations: Carbon in pitcher filters works for mild odors. It’s not designed to handle the volume or concentration of moderate-to-high H2S levels from a well.

Ignoring it: H2S corrodes copper pipes, fixtures, and water heaters over time. The aesthetic problem tends to get worse, not better, without treatment.

Related:

Sources: EPA Secondary Drinking Water Standards | EPA Private Wells Contaminant Guide

Frequently Asked Questions

What removes hydrogen sulfide from well water?
It depends on the concentration and source. Low levels respond to activated carbon filtration. Moderate levels need aeration, which physically strips the gas from the water before it enters your home. High levels or a bacterial source require continuous chlorination followed by carbon filtration. If only your hot water smells, the source is likely your water heater anode rod, not the well. Replacing a magnesium anode with an aluminum/zinc rod eliminates that cause completely.
Is hydrogen sulfide in well water dangerous?
At concentrations found in residential wells, hydrogen sulfide is an aesthetic problem, not a health hazard. The EPA has no health-based MCL for H2S in drinking water. The smell is the issue, not toxicity. That said, very high concentrations in confined spaces can be hazardous, but tap water concentrations are far below those levels.
Will a Brita filter remove rotten egg smell?
For low-level hydrogen sulfide, activated carbon in a pitcher filter can reduce the smell. But pitcher filters aren't designed for moderate or high H2S levels. If the smell is strong or the concentration is above 0.1 mg/L, you need a whole-house aeration or chlorination system rather than a point-of-use carbon filter.
Why does only my hot water smell like rotten eggs?
When only the hot water smells, the source is your water heater, not your well. Magnesium anode rods inside most tank water heaters react with sulfates in the water to produce hydrogen sulfide gas. The fix is replacing the magnesium anode with an aluminum/zinc combination anode. This eliminates the reaction. It's not a well contamination issue.
Does chlorination remove hydrogen sulfide?
Yes. Continuous chlorination oxidizes hydrogen sulfide into solid sulfur particles, which are then filtered out. This approach is used for high H2S levels or when iron bacteria are confirmed as the source. The water must pass through a contact tank to allow the reaction to complete, then through a carbon filter to remove residual chlorine and any remaining odor. It's a whole-house solution, not a point-of-use one.