How To Treat Sulfur Odors In Well Water

air charger sulfur filtersWater containing hydrogen sulfide gas (“H2S”), has a distinctive “rotten egg” odor, which may be especially noticeable when running hot water.

Such water can discolor coffee, tea, and other beverages, and alter the appearance and taste of cooked foods. Hydrogen sulfide (“H2S”) gas is a nuisance that is not usually a health risk at concentrations normally found in household water.

Hydrogen sulfide can be toxic. Usually, the gas can be detected long before it reaches harmful concentrations. H2S is flammable and poisonous.

While such concentrations are not common, if gasses are released in a confined area, they could cause nausea, illness, and in extreme cases, death.

Also see our section “Odor Systems” for filters and systems to remove odors from well water.

H2S dissolved in water can corrode plumbing metals, such as iron, steel, copper, and brass and exposed metal parts in washing machines and other water-using appliances.

The corrosion of iron and steel from hydrogen sulfide forms ferrous sulfide or “black water” which can darken silverware and discolor copper and brass utensils.

Hydrogen sulfide can also interfere with the effectiveness of water softeners and filter systems.

Sources of Hydrogen Sulfide

water heater odor killerIron bacteria and sulfur bacteria present in groundwater use iron and sulfur as an energy source and chemically change sulfates to produce H2S gas.

These bacteria use the sulfur available from decaying plants, rocks, or soil and often thrive in an iron-rich environment. The harmless non-toxic bacteria normally exist in oxygen-deficient environments, such as deep wells and plumbing systems. The bacteria do not usually cause health problems but contribute to bad tastes and/or odors at low levels.

The harmless non-toxic bacteria normally exist in oxygen-deficient environments, such as deep wells and plumbing systems. The bacteria do not usually cause health problems but contribute to bad tastes and/or odors at low levels.

Hydrogen sulfide gas may also be present naturally in wells drilled in shale or sandstone, near coal or peat deposits, or in oil fields. Though H2S is normally found in wells, it can also enter surface water through springs and quickly escape into the atmosphere.

Often water heaters can also become a source of foul H2S odors. The magnesium rod used in heaters for corrosion control can chemically reduce sulfates to H2S and may need to be replaced with a different type of anode. This odor can also be eliminated with the use a Water Heater Odor Killer.

Test Your Water

well water test kitIf there is an odor problem with the water supply, the first step is to determine the source. If the source is from the well directly a general mineral water analysis is critical to select the correct system.

The test should include analysis for pH, iron, manganese, hardness, total dissolved solids at a minimum. Additional tests for sulfate, hydrogen sulfide and tannin is recommended as well. Take the sample as close to the well as possible.

With these results, you can identify the best type of water treatment to use, and what type of system to select, based on your water chemistry.

For health-related issues, the water should be tested for total coliform and e-Coli (fecal coliform). If infants and children will be drinking the water, a  general, mineral, metals and a bacteriological test is recommended.

If the source of water is a public water system and you experience problems with odor, it is important to contact a utility official to determine whether the odor is from the public system or from the home’s plumbing or piping.

Check For Odors in Cold & Hot Water

Run a hose bib or tap as close to the well as possible and fill a 5- gallon bucket or other container and notice if there are odors. If you smell a “rotten egg” odor, this is hydrogen sulfide gas. If the water smells like oil or asphalt this can be from manganese. If your water smells like cucumber or sewage this is usually a result of iron and/ or sulfur bacteria.

Run the water hot water from each tap and notice if there is an odor in the hot water, that is not in the cold water. This indicates a problem with the water heater. Iron and sulfur bacteria can interact with the anode rod in water heaters, resulting in hydrogen sulfide gas only in the hot water. Changing the anode rod to an aluminum rod can often solve this problem.
shock chlorination

Use a Chlorinator to Kill Odor and Bacteria

Precision-24 Odor Killer Chlorinators Eliminate Both Odors and Odor-Causing Bacteria

  • Uses 5% grade liquid bleach or 12% liquid pool chlorine!
  • An easy and precise dosage of chlorine makes it easy to control.
  • Optional whole house carbon filter removes any residual chlorine in the water.
  • The result is clean, fresh, disinfected water throughout the home.
  • Works over a wide range of water flow rates for most home water wells
  • Good for chlorinating well water flow rates from 1 to 50 Gallons Per Minute (1 – 50 GPM)
  • Pumps 0.1 to 24 gallons of solution per day
  • Works for line pressures up to 110 PSI
  • Choose 120v or 220v. Uses only 22 watts of power.
  • Dimensions: 15 gallon model: 14.5″ wide x 24″, height including pump is 35″.
    35 gallon model: 18″ wide x 33″, height including pump is 44″.
  • Stroke frequency adjustable from 0 to 100 strokes per minute
  • Digital speed adjustment makes adjusting the pump fast and easy for incredibly accurate injection
  • De-gassing vent built-in makes the pump great for chlorination use
  • Unlike Stenner-style peristaltic pumps: no pump tube failures, no rollers to go bad, needs less service, and good for continuous duty
  • Uses regular household bleach (5% sodium hypochlorite) or liquid pool chlorine (12% sodium hypochlorite)
  • These heavy-duty metering pumps systems are designed to last for many years
    with minimal maintenance.
  • Pump easily mounts on the top of the tank or a wall
  • Primes super fast, and won’t lose its prime.
  • Complete system includes chlorinator pump, solution tank, injection check valve, tubing, fittings


  • Clean Water Systems & Stores, Inc., Water Treatment Equipment,Service & Supplies, Santa Cruz, CA