Sulfurous water generally refers to water with dissolved Hydrogen Sulfide content or the presence of Sulfur bacteria as seen in the photo to the right.

This particular problem water most often affects homes or businesses using well water, those in areas where the water supply could be easily compromised, or areas that may be poorly or irregularly treated and monitored.

If sulfurous water is found, it may also be a sign of a contaminated water heater.

Two forms of Sulfur are commonly found in drinking water supplies: Sulfate and Hydrogen Sulfide.

Both forms are nuisances that usually do not pose a health risk at the concentrations found in domestic water supplies.

Sulfides of many important metallic elements are naturally occurring minerals. For example, pyrite, which is also called fool’s gold owing to its brassy yellow colour, is a sulfide of iron with the formula FeS2.

Pyrite is a major source of iron and is one of the most abundant of the sulfur minerals. Zinc, Cadmium, Mercury, Copper, Silver, and many other elements occur in nature as Sulfides.

Sulfates are a combination of Sulfur and Oxygen and are a part of naturally occurring minerals in some soil and rock formations that contain groundwater.

The mineral dissolves over time and is released into groundwater.

In addition, this problem may be related to a community hazard, such as a: landfill, leaky fuel tank, pipeline, old septic system, chemical lab, and many other community hazards.

Sulfur-reducing bacteria, which use Sulfur as an energy source, are the primary producers of large quantities of Hydrogen Sulfide.

These bacteria chemically change natural Sulfates in water to Hydrogen Sulfide.

Sulfur-reducing bacteria live in Oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters.

These bacteria usually flourish on the hot water side of a water distribution system.

Hydrogen Sulfide gas also occurs naturally in some groundwater. It is formed from decomposing underground deposits of organic matter such as decaying plant material. It is found in deep or shallow wells and also can enter surface water through springs, although it quickly escapes into the atmosphere.

Hydrogen Sulfide often is present in wells drilled in shale or sandstone, or near coal or peat deposits or oil fields.

Occasionally, an electric water heater is a source of Hydrogen Sulfide odor. The Magnesium corrosion control rod present in many water heaters can chemically reduce naturally occurring Sulfates to Hydrogen Sulfide.

While Hydrogen Sulfide content and Sulfur bacteria in water is not inherently dangerous, few would argue it’s pleasant.

Sulfur in your water can also create slime that results in the growth of other bacteria, like iron bacteria, in water.

Presence of these bacteria can lead to problems with plumbing and appliances, eventually corroding pipes and fixtures.

Sulfate

Sulfate may have a laxative effect that can lead to dehydration and is of special concern for infants. With time, people and young livestock will become acclimated to the sulfate and the symptoms disappear. Sulfur-oxidizing bacteria pose no known human health risk.

The maximum contaminate level is 250 mg/L.

Hydrogen Sulfide

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 odors may be from sewage pollution which can contain disease-producing contaminants.

Therefore, testing for bacterial contamination and Sulfate Reducing Bacteria is highly recommended.