Sulfur water is defined by a distinct, unpleasant odor, often described as rotten eggs, caused by dissolved hydrogen sulfide (\(\text{H}_{2}\text{S}\)) gas. This gas is a byproduct of naturally occurring chemical reactions or certain bacteria in groundwater supplies. While the smell is a nuisance, the answer to whether sulfur water can make you sick is nuanced. The water is often problematic due to co-occurring high mineral levels or the potential for pathogenic contamination, rather than the hydrogen sulfide itself.
The Difference Between Odor and Health Risk
The offensive rotten egg smell is created by hydrogen sulfide gas, which is detectable by humans at extremely low concentrations, sometimes as low as 0.5 parts per million (ppm). This low threshold means the odor serves as a powerful aesthetic warning. The \(\text{H}_{2}\text{S}\) concentration rarely reaches levels considered a direct threat to health when consumed. The United States Environmental Protection Agency (EPA) does not regulate hydrogen sulfide as a primary health contaminant because toxic concentrations are so unpalatable that a person would be unlikely to drink the water.
The presence of this gas does pose indirect concerns, however. Hydrogen sulfide is corrosive and can damage plumbing, leading to the release of heavy metals like lead and copper into the drinking water. When water containing \(\text{H}_{2}\text{S}\) is used in confined spaces like a shower, the gas can escape into the air. In rare instances, this can reach concentrations that cause respiratory or eye irritation. While the gas itself is not usually toxic to drink, it often creates secondary issues, including a bitter taste, making the water unappealing.
Direct Health Effects of High Sulfate Levels
A more direct cause of illness associated with sulfur water comes from high concentrations of sulfates. Sulfates are naturally occurring minerals composed of sulfur and oxygen dissolved from soil and rock. They frequently occur alongside hydrogen sulfide and are the primary source of gastrointestinal distress experienced by some individuals. High levels of sulfates bound to magnesium or sodium can act as a natural laxative, leading to diarrhea and potential dehydration.
This laxative effect is most pronounced in people new to the water source, such as visitors, or in sensitive populations like infants. A sulfate concentration above 600 milligrams per liter (mg/L) is often associated with a strong cathartic effect, though a mild laxative response can occur above 500 mg/L. Over time, most healthy individuals become acclimated to the high sulfate levels, and the symptoms diminish. The EPA’s secondary standard for sulfates is set at 250 mg/L, but this limit is based on aesthetic issues like taste and odor, not on health effects.
The Role of Bacteria in Water Contamination
The rotten egg smell is often produced by sulfur-reducing bacteria (SRB). SRB chemically convert sulfates into hydrogen sulfide gas in oxygen-deficient environments, such as deep wells or water heaters. While SRB are generally not considered disease-causing organisms, their presence indicates an anaerobic environment and a potential sanitation problem. These bacteria create a slime that can encourage the growth of other, potentially more harmful microorganisms.
The primary health danger is the potential for pathogenic bacteria, such as E. coli or total coliforms, to co-exist in the compromised water source. If the hydrogen sulfide odor results from sewage or pollution entering the well, the water is at risk of containing these disease-causing contaminants. The resulting illness would be severe, involving symptoms like fever, cramping, and vomiting, caused by the pathogenic bacteria, not the hydrogen sulfide or sulfates.
Testing and Treatment Options for Sulfur Water
Identifying the exact cause of the sulfur issue requires professional water testing. This determines if the problem is primarily chemical (high sulfates) or microbiological (SRB or pathogens). Testing for hydrogen sulfide gas is best done on-site, as the gas escapes quickly from the water, while sulfate levels require a laboratory analysis. If the water source is a private well, testing for coliform bacteria is recommended, especially if sewage contamination is suspected.
The treatment method depends heavily on the test results and the specific sulfur compound present. For removing hydrogen sulfide odor, common solutions include aeration, which introduces air to dissipate the gas, or oxidation filters. Oxidation filters convert the gas into solid sulfur particles that can then be filtered out. If bacterial contamination is the source of the odor, shock chlorination is effective for killing the bacteria. High sulfate levels are more difficult to treat but can be reduced using specialized systems like reverse osmosis or distillation.