Sulfur is a soft, bright yellow element also known as brimstone because it will burn, producing sulfur dioxide (SO₂) and giving off a characteristic odor. It is associated with volcanism and minefires. Some near-surface coal mine fires in our area of Pennsylvania emit sulfur vapor which condenses on the underside of loose rock. Flip over the rock and you can see the bright yellow sulfur deposits. Sulfur normally does not stay in elemental form. Since sulfur, the element, is essentially insoluble in water, it is not a problem in drinking water.
Sulfur has many oxidation states in compounds but the most common and of interest to us are –2, –1, and +6. If there is very little oxygen available, sulfur will be reduced to an oxidation state of –2 or –1 and form sulfide compounds. In pyrite (FeS₂) the sulfur has an oxidation state of –1 while in hydrogen sulfide (H₂S) the sulfur has an oxidation state of –2. If there is abundant oxygen available, sulfur will be oxidized to an oxidation state of +6 and form sulfate (SO₄=) compounds such as gypsum (CaSO₄•2H₂O) and sulfuric acid (H₂SO₄).
Sulfides are stable in low oxygen environments whereas sulfates are stable in high oxygen environments. Things get interesting when sulfides are exposed to a high oxygen environment or when sulfates move into a low oxygen environment because in changing to a more stable form in the new environment, they can end up in water.
Sulfides, with one important exception, are very insoluble in water. However, should they be exposed to the air, they can weather, oxidize, and release sulfate anions into water. Pyrite, a sulfide mineral, is commonly associated with coal. Coal mining breaks up the pyrite where much of it ends up in rock waste piles (locally known as culm banks) where it is exposed to air and water. The pyrite breaks down in this oxygen-rich environment, releasing large amounts of dissolved iron and sulfuric acid into the mine water; the sulfuric acid (H₂SO₄) is the acid in acid mine drainage. The acid quickly and completely dissociates in water to produce H+ (the acid part) and the sulfate anion (SO₄=). The acid can be neutralized but the sulfate remains in solution.
Certain bacteria can take advantage of the oxidation or reduction of sulfur because such chemical changes are a source of energy. Sulfur-reducing bacteria thrive when sulfate-rich water moves into a low oxygen environment. Such bacteria mediate the transformation of sulfate into hydrogen sulfide which, being a gas, can dissolve into water; this is the important exception to sulfides being very insoluble in water. Sulfur-oxidizing bacteria do the opposite, deriving energy by mediating the oxidation of sulfides into sulfates in oxygen-rich environments.
Sulfur, then, can create various problems in drinking water: sulfate and hydrogen sulfide gas, plus various sulfur bacteria that facilitate their production, and insoluble sulfide particles suspended in the water.
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. Elevated levels of sulfates are typically associated with elevated levels of Sodium, calcium, magnesium, high Alkalinity, and in some cases brine or very salty water.
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. 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.
Hydrogen sulfide gas also occurs naturally in some groundwater, and is formed from decomposing underground deposits of sulfur-containing 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 to the atmosphere. Hydrogen sulfide is often present in wells drilled in shale or sandstone, near coal or peat deposits, and in oil fields. The odor of water with as little as 0.5 ppm of hydrogen sulfide concentration is detectable by most people. Concentrations less than 1 ppm give the water a "musty" or "swampy" odor. A 1-2 ppm hydrogen sulfide concentration gives water a "rotten egg" odor and makes the water very corrosive to plumbing. Generally, hydrogen sulfide levels are less than 10 ppm, but have been reported as high as 50 to 75 ppm.
Warning: the nose fairly quickly loses the ability to smell hydrogen sulfide; the odor seems to disappear but there may still be high amounts of hydrogen sulfide in the air. It can oxidize to sulfuric acid in the throat which irritates the throat tissues; you might notice that your voice becomes hoarse. Continued high exposure could irritate the throat so much that the throat swells shut, resulting in suffocation.
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.
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. However, because of the pH of an infant's stomach, Infants are vulnerable to sulfate which can produce dehydration and diarrhea.
The EPA has set a recommended Secondary Drinking Water Standard for sulfates at a level of 250 mg/L, because of the laxative effects of the water. Elevated levels of sulfate may be associated with the presence of hydrogen sulfide gas and black particles of iron and/or manganese sulfide. The EPA has no standard for hydrogen sulfide in water.
Like many contaminants in drinking water this anion creates a potential health issue at a level that is not easy to detect. High levels of sulfate will not always be associated with an odor, taste, or appearance problem. In some cases, the elevated level of sulfate will be suspected because when the water evaporates there is a white or gray powdery solid. Your best course of action is to get your water tested and to compile as much information as possible about your water supply source, well construction, surrounding land-use, and local geology.
Level 1 Testing is done with simple observations that an individual can make with their own senses such as sight, smell, and taste. These observations can be readily apparent or can be observed as they change over time. In addition, accessible related information about the home can also be used to narrow down the cause of your water issues.
You will suspect a problem with sulfate if the water has a sulfur odor, black particles, or you are experiencing diarrhea.
As previously mentioned, problems with hydrogen sulfide will typically be most evident by smell, but it can also be associated with other aesthetic issues, such as discolored water, premature failure of water related equipment and fixtures, and corrosion of fixtures. Sulfate is usually not so obvious.
Level 2 Testing is Do-It-Yourself testing that can be done in your own home using a Testing Kit. After you’ve done Level 1 Testing, Level 2 Testing can confirm if your observations are correct. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment (see below) or continue to Level 3 Testing.
Sulfate test strips are a reliable and easy way to screen your drinking water for the presence of sulfates. It is basically a test where you dip a test strip in the water and then after a 2 minute wait (Yes you have to wait 2 minutes) you get a result. There are also test strips and affordable screening tests for sister compounds like sulfide, hardness, and metals. A number of pathogens are associated with sulfur odors.
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-chloroform-trichloromethane">Note: If the concentration is < 0.080 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-ethylbenzene">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-methylene-chloride-dichloromethane-dcm">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-xylenes">Note: If the concentration is < 1 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-atrazine">Note: If the concentration is < 0.001 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-alachlor">Note: If the concentration is < 0.002 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-glyphosate">Note: If the concentration is < 0.7 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-2-4-d">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-bis-2-ethylhexyl-phthalate">Note: If the concentration is < 0.006 mg/L (POE Device System Component</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POE Device System Component)</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POU Device System Component)</div>
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-chloroform-trichloromethane">Note: If the concentration is < 0.080 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-ethylbenzene">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-methylene-chloride-dichloromethane-dcm">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-xylenes">Note: If the concentration is < 1 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-atrazine">Note: If the concentration is < 0.001 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-alachlor">Note: If the concentration is < 0.002 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-glyphosate">Note: If the concentration is < 0.7 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-2-4-d">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-bis-2-ethylhexyl-phthalate">Note: If the concentration is < 0.006 mg/L (POE Device System Component</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POE Device System Component)</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POU Device System Component)</div>
Level 3 Testing is done through an accredited Water Testing Laboratory. With Level 3 Testing, you can order a testing kit that is used to prepare your sample and submit it to the lab. By utilizing a lab, you have the assurance that a certified water expert had analyzed your water sample. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment options (see below) or continue to Level 4 Testing - Certified Testing.
If you conduct an informational water quality test, we suggest a testing package that includes trace metals, bacteria, nutrients, and sulfur compounds. If you are experiencing a sulfur odor we would suggest testing for nuisance bacteria and if you are in an agricultural or industrial area we also suggest test for volatile organic compounds (VOCs) and synthetic organic compounds (SOCs). This is not a common problem in city water, but if you have this problem we recommend flushing your water line until you smell chlorine, contacting your water supplier, and conducting a City Water Basic and a Sulfate Related Bacteria Test.
For well water sources and some city water systems we have found that intermittent sulfur odors have been related to bacteria regrowth in the distribution system; for these systems we recommend that the source and piping be shock disinfected. Regarding the hot water lines, we suggest pasteurizing and flushing the heating system.
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-chloroform-trichloromethane">Note: If the concentration is < 0.080 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-ethylbenzene">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-methylene-chloride-dichloromethane-dcm">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-xylenes">Note: If the concentration is < 1 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-atrazine">Note: If the concentration is < 0.001 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-alachlor">Note: If the concentration is < 0.002 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-glyphosate">Note: If the concentration is < 0.7 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-2-4-d">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-bis-2-ethylhexyl-phthalate">Note: If the concentration is < 0.006 mg/L (POE Device System Component</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POE Device System Component)</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POU Device System Component)</div>
A Level 4 Certified Test Test uses chain-of-custody with a water professional coming to your home to prepare the water sample and then works with an accredited laboratory in order to certify your test results. This type of testing not only gives you the highest level of assurance in the accuracy of your test results, but can also be used as a document in legal cases. For Baseline Testing, we recommend that you use Certified Testing.
A problem with hydrogen sulfide gas may be associated with a chemical or biochemical issue with the water. Before conducting certified testing, it is advisable to conduct preliminary informational testing including microbiological testing and, at a minimum, an attempt to flush and shock disinfect the source and distribution system.
Several methods of removing sulfate from water are available. The treatment method selected depends on many factors including the level of sulfate in the water, the amount of iron, manganese, and salts in the water, water pH and oxidation potential, and whether bacterial contamination requires treatment. The option you choose also depends on how much water you need to treat and the chemistry of the water.
For treating small quantities of water, for drinking and cooking only, the typical treatments are distillation or reverse osmosis. The most common method of treating large quantities of water is ion exchange. This process works similar to a water softener. An ion-exchange resin, contained inside the unit, adsorbs sulfate. When the resin is loaded to full capacity with sulfate, treatment ceases. The resin then must be "regenerated" with a salt (sodium chloride) brine solution before further treatment can occur. Distillation boils water to form steam that is then cooled and condensed. Minerals, such as sulfate, do not vaporize with the steam and are left behind in the boiling chamber. Reverse osmosis membranes have a porosity that permits water molecules to pass through but leaves the large ions, including sulfate, in solution.
Hydrogen sulfide may be temporarily controlled by conducting a shock chlorination / disinfection of the well or water source as well as the piping within the home. If the problem with your water is because of sulfate reducing bacteria or anaerobic bacteria, a high level of chlorination, mixing, and turbulence may be needed during the Shock Disinfection process.
To remove low levels of hydrogen sulfide, install an activated-carbon filter. The filter must be replaced periodically to maintain performance. Frequency of replacement will depend on daily water use and concentration of hydrogen sulfide in the water and this assumes the problem is NOT related to bacteria.
If the hydrogen sulfide odor is associated primarily with the hot water system, a hot water heater modification may reduce the odor or you may need to pasteurize the system. If the odor is stronger in the electric water tank, we recommend the following:
a. Turn off the system and drain the tank. Note any anomalies such as: the color and odor of the water, coatings, precipitates, or other solid materials.
b. Allow the tank to refill, but raise the temperature setting of the tank to a level above 140 °F.
c. Allow the tank to stay at this level for at least 6 to 10 hours.
d. Turn off the system and reduce the system to the normal temperature setting.
e. Drain any discolored water and then allow the tank to refill.
f. If the odor goes away it was most likely bacteria growing in the tank that is causing the problem.
g. If the odor returns immediately it is likely a chemical reaction between the water and the sacrificial anode used in the system.
It would be advisable to check the quality of the water entering the tank.
If you have a well, we recommend that you also Shock Disinfect the well and distribution system.
If sediment is entering or leaving the system, you might want to consider a RUSCO 1-1/2-60 Hot Water Spin-Down Filter System. You would install this on the inlet side of the water heating tank and add peroxide to aid in the disinfection process. If this does not work, try replacing the magnesium anode rod with an aluminum anode, or remove the system and install either an on-demand system, a plastic-lined tank, or a commercial stainless steel unit.
City water users should not have a problem with sulfates because the drinking water supplier in most cases is required to ensure the level of sulfate is below 250 mg/L, but city water users may experience problems with hydrogen sulfide gas. If you are a city water customer and there is a sulfur smell to your water, the first step is to check to see if the odor is present in the water when it enters the home or building. If there is no problem at the entry point, the problem is most likely a bacterial regrowth in the water distribution system for the building or a back flow problem in the building. The next step would be to check for back flow issues and shock disinfect and flush all water lines.
It is possible that the level of sulfate may be elevated in well water and other private systems. If there is no sulfur gas smell, the short-term treatment solution may be the installation of a point-of-use device and/or the use of an alternative water source. If there is any odor anywhere in the water, the first step would be a shock disinfection of the system and a pasteurization of the hot water lines. Do not boil the water; it is likely this would increase the sulfate concentration in the water although it would drive out any hydrogen sulfide gas, maybe not such a good idea inside the building..
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-chloroform-trichloromethane">Note: If the concentration is < 0.080 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-ethylbenzene">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-methylene-chloride-dichloromethane-dcm">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-xylenes">Note: If the concentration is < 1 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-atrazine">Note: If the concentration is < 0.001 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-alachlor">Note: If the concentration is < 0.002 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-glyphosate">Note: If the concentration is < 0.7 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-2-4-d">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-bis-2-ethylhexyl-phthalate">Note: If the concentration is < 0.006 mg/L (POE Device System Component</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POE Device System Component)</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POU Device System Component)</div>
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Sulfate - For treating small quantities of water, drinking and cooking only, the typical methods are distillation or reverse osmosis. The most common method of treating large quantities of water is ion exchange. This process works similar to a water softener. An ion-exchange resin, contained inside the unit, adsorbs sulfate. When the resin is loaded to full capacity with sulfate, treatment ceases. The resin then must be "regenerated" with a salt (sodium chloride) brine solution before further treatment can occur. Distillation boils water to form steam that is then cooled and condensed. Minerals, such as sulfate, do not vaporize with the steam and are left behind in the boiling chamber. Reverse osmosis membranes have a porosity that permits water molecules to pass through but leaves the large ions, such as sulfate, in solution.
Hydrogen Sulfide/Sulfide - For this situation , the system can include either an aeration system to drive out the dissolved gas or an oxidation-filtration system that drives off the gas and oxides sulfides into a particle that can be filtered. If the gas is associated with a nuisance bacteria, the oxidation process will need to include a strong oxidizer that can disinfect the water.
Because problems with sulfur and hydrogen sulfide are normally complex issues, we recommend that you hire a local professional to develop a long-term solution. If you need assistance in finding a local professional or would like a second opinion, please contact us.
<div class="product-note in-L6-benzene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-chloroform-trichloromethane">Note: If the concentration is < 0.080 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-ethylbenzene">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-methylene-chloride-dichloromethane-dcm">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-mtbe-methyl-tert-butyl-ether">Note: If the concentration is < 0.07 mg/L</div>
<div class="product-note in-L6-tetrachloroethylene">Note: If the concentration is < 0.005 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-trichloroethylene">Note: If the concentration is < 0.004 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-toluene">Note: If the concentration is less than 0.8 mg/L</div>
<div class="product-note in-L6-xylenes">Note: If the concentration is < 1 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-atrazine">Note: If the concentration is < 0.001 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-alachlor">Note: If the concentration is < 0.002 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-glyphosate">Note: If the concentration is < 0.7 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-2-4-d">Note: If the concentration is < 0.03 mg/L (POE Device System Component)</div>
<div class="product-note in-L6-bis-2-ethylhexyl-phthalate">Note: If the concentration is < 0.006 mg/L (POE Device System Component</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POE Device System Component)</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L (POU Device System Component)</div>
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