EcoWater Spokane

Spokane's Ecological choice for fresh water

Sulfur Smell in Well Water

The sulfur smell in well water is due to the presence of the gas contaminant, hydrogen sulfide (H2S). This gas is a common contaminant of well water and is usually produced by certain types of bacteria as a waste product. Hydrogen sulfide gas produces an offensive “rotten egg” or “sulfur water” odor and taste in the water. Two forms of sulfur are commonly found in drinking water supplies: sulfate and hydrogen sulfide.

In some cases, the odor may be noticeable only when the water is initially turned on or when hot water is run. Heat forces the gas into the air which may cause the odor to be especially offensive in a shower. Occasionally, a hot water heater is a source of hydrogen sulfide odor. The magnesium corrosion control rod present in many hot water heaters can chemically reduce naturally occurring sulfates to hydrogen sulfide.

What’s the difference between Sulfates and Hydrogen Sulfide?

Hydrogen sulfide is a gas with an offensive “rotten egg” odor. Water in many regions contains dissolved hydrogen sulfide in deep or shallow wells. In deep wells it is commonly associated with oil and gas fields. In shallow wells it is generally caused by decaying vegetation such as that found in swampy areas that feed an aquifer. In shallow wells the effect may be seasonal; the odor may be more prevalent when water tables are at their highest (fresh recharge from surface water sources).

Hydrogen sulfide smell can be detected down to 0.5 mg/L or even lower at high pH. At modest concentrations it can also stain silverware. Because it is a gas, hydrogen sulfide should be measured at the well or faucet immediately after collection to get an accurate measure of concentration.

Sulfates are a combination of sulfur and oxygen. These elements are naturally occurring minerals in some soil and rock formations that contain groundwater. The minerals dissolve over time and gradually released into groundwater.

Sulfur-reducing bacteria are the primary producers of large quantities of hydrogen sulfide. These bacteria use sulfur as an energy source, chemically changing natural sulfates in water to hydrogen sulfide. These bacteria usually flourish on the hot water side of a water distribution system.

Household Tell-Tale Signs

Sulfate minerals can cause scale buildup in water pipes similar to other minerals and may be associated with a bitter taste in water that can have a laxative effect on humans and young livestock. Elevated sulfate levels in combination with chlorine bleach can make cleaning clothes difficult. Sulfur-oxidizing bacteria produce effects similar to those of iron bacteria. They convert sulfide into sulfate, producing a dark slime that can clog plumbing and/or stain clothing. Blackening of water or dark slime coating the inside of toilet tanks may indicate a sulfur-oxidizing bacteria problem. Sulfur-oxidizing bacteria are less common than sulfur-reducing bacteria.

A nuisance associated with hydrogen sulfide includes its corrosiveness to metals such as iron, steel, copper and brass. It can tarnish silverware and discolor copper and brass utensils. Hydrogen sulfide also can cause yellow or black stains on kitchen and bathroom fixtures. Coffee, tea and other beverages made with water containing hydrogen sulfide may be discolored and the appearance and taste of cooked foods can be affected.

Potential Health Effects

Sulfate may have a laxative effect that can lead to dehydration and is of special concern for infants. Hydrogen sulfide is flammable and poisonous. Usually it is not a health risk at concentrations present in household water, except in very high concentrations. While such concentrations are rare, hydrogen sulfide’s presence in drinking water when released in confined areas has been known to cause nausea, illness and, in extreme cases, death. Water with hydrogen sulfide alone does not cause disease. In rare cases, however, hydrogen sulfide odor may be from sewage pollution, which can contain disease-producing contaminants. Therefore, testing for bacterial contamination and Sulfate Reducing Bacteria is highly recommended.

Recommended Sulfate Treatment System:

  • Option 1 – EcoWater Systems model ESS1000XR32 w/anion resin A300E

Recommended Hydrogen Sulfide Treatment System:

  • Option 1 – EcoWater Systems ETF AIIF9 chemical-free iron filter
  • Option 2 – EcoWater Systems ETF 2100-IF10 iron filter w/manganese greensand media
  • Option 3 – EcoWater Systems ETF 2100-IF10 iron filter w/MTM media
  • Option 4 – EcoWater Systems ETF 2100-PF10 filter w/KDF 85 media
  • Option 5 – EcoWater Systems ETF 2100-PF series of filters w/Filox-R media
  • Option 6 – EcoWater Systems ETF 2100-PF10 filter w/Pyrolox media