Smells & odors in drinking water:

Catalog of methods for removing sulfates or hydrogen sulfide from drinking water. This article describes water treatment methods to remove sulfates, hydrogen sulfide (H₂S), sulphur odors or rotten egg smells from the building water supply.

This is the second part of our article series discussing how to identify, diagnose, and cure common odors that may be present in drinking water.

We also discuss which of these odors may warn of unsanitary conditions.

Treatments for Sulphur Odors in Water

Discussed here: Water sulphur odours or rotten egg smells: diagnosis and cure. How to get rid of or treat stinks, smells, rotten egg odor, sulphur odors in water.

How to diagnose the cause of rotten egg sulphur odors in drinking water, Are there health risks associated with some water odors?

Water treatment systems to remove sulphur odors are available from water treatment companies. What you need to cure a sulphur odor depends on the duration (seasonal versus all year), cause (water supply versus piping or water heater), and severity.

Article Contents

• WATER ODOR TREATMENTS, CURES - SULPHUR
  • CHLORINE BLEACH INJECTION
  • DISTILLATION to REMOVE WATER ODORS
  • FILTERS to REMOVE WATER ODORS
  • GREENSAND POTASSIUM PERMANGANATE OXIDIZERS
  • REVERSE OSMOSIS to REMOVE WATER ODORS
  • SHAKE & WAIT to REMOVE SULPHUR ODOR from WATER
  • UV WATER TREATMENT & WATER ODORS
  • WATER HEATER CAUSES of WATER ODORS
  • WATER SOFTENERS CAN REMOVE SULPHUR ODORS
  • WELL SHOCK to REMOVE SULPHUR ODORS
  • SULPHUR ELIMINATOR at the WELL
  • OTHER SOURCES of ODORS

Importance of diagnosing the cause of sulphur odors in water before trying to get rid of it

Watch out: to properly get rid of an odor in water it's useful to properly diagnose its cause.

For example shocking a well or even installing a water treatment or water filter system for sulphur won't get rid of a sulphur odor in hot water that is coming from a bacterial contamination in the water heater tank nor from a failed water heater tank sacrificial anode.

See WATER ODOR DIAGNOSIS - SULPHUR

Or for a complete guide to sources of and cures for odors in water

see WATER ODORS, CAUSE CURE - home.

Water Treatment Methods s to Remove Sulphur Odors

The choice of water treatment method to remove sulphur smells depends on the cause of the problem and its severity. The treatment methods discussed here are listed alphabetically and include comments on the level of sulphur for which the method is suitable.

Chlorine (Bleach) Injection Systems To Remove Sulphur Odors

Higher levels of hydrogen sulfide (H₂S) in the water supply in the 7-10 ppm range are often treated by using a chlorine injection system. Controlled by a pump and mixed in a mixing tank, a bleach solution (chlorine) is injected into the water supply by a control that uses a timer or a device that measures water consumption.

The mixing tank is required to allow sufficient contact time between the chlorine molecules and the (H₂S) (or in some cases also bacteria) in the water supply to oxidize the contaminant.

Because this chlorine/bleach oxidation process produces a sediment (such as sulphur particles or sulphur dioxide particles), a chlorine injection system is almost always combined with a filtering system downstream from the chlorinator.

The filter, often combining a sediment filter stage with an activated charcoal stage, removes both particulate sediment and also the residual "chlorine" odor from the water.

See CHLORINATORS & CHARCOAL FILTERS

Research:

• Ellenberger, Christine Spada. "Water Quality Impacts of Pure Chlorine Dioxide Pretreatment at the Roanoke County (Virginia) Water Treatment Plant." PhD diss., Virginia Polytechnic Institute and State University, 1999.
• Glaze, William H., Raymond Schep, William Chauncey, Edward C. Ruth, Joseph J. Zarnoch, E. Marco Aieta, Carol H. Tate, and Michael J. McGuire. "Evaluating oxidants for the removal of model taste and odor compounds from a municipal water supply." Journal (American Water Works Association) (1990): 79-84.
• Tsuchiya, Y., M. F. Watanabe, and M. Watanabe. "Volatile organic sulfur compounds associated with blue-green algae from inland waters of Japan." Water Science and Technology 25, no. 2 (1992): 123-130.
• White, George C., Elwood L. Bean, and D. B. Williams. "Chlorination and Dechlorination: A Scientific and Practical Approach [with Discussion]." Journal (American Water Works Association) 60, no. 5 (1968): 540-561.

Distillers to Remove Water Odors including Sulphur or Rotten Egg Smells

A distiller will remove most odors and many other contaminants from water. Distillers boil the water to make steam in a process that releases volatiles as a gas and that leaves other impurities behind as a sludge in the water.

Distillers, like reverse osmosis systems discussed later in this article, are suitable for treating small volumes of water such as for drinking.

Details are at DISTILLATION for DRINKING WATER DISINFECTION.

Odor Filters to Remove Sulphur Smells

The easiest way to get rid of sulfur odor is to use a filter with activated charcoal or carbon. Odor filters, typically using an activated charcoal canister filter cartridge, are widely sold to remove sediment and odors from the water supply.

Watch out: because charcoal is such an effective filter, a charcoal filter can collect organic debris that in turn forms a home for bacterial growth. For this reason water treatment systems intended to rely on filtration often combine a chlorinator with a charcoal or other filtering system.

The chlorinator is placed ahead of the charcoal filter.

Some filtration systems use a cascade of filters that permits longer life for the more downstream filters. For example we place a sediment filter first to reduce clogging of the charcoal filter.

See WATER FILTERS, HOME USE

Watch out: failure to change any water filter on a sufficiently-frequent schedule can expose building occupants to bacterial hazards originating in a contaminated filter.

Research:

• Falconer, Ian R., Maria TC Runnegar, Tom Buckley, Van L. Huyn, and Peter Bradshaw. "Using activated carbon to remove toxicity from drinking water containing cyanobacterial blooms." Journal (American Water Works Association) (1989): 102-105.

Ozone Treatment for Sulphur Odors in Water

Ozone treatment has been used for both odor removal (by oxidation) and disinfection treatment of water.

See details at OZONE for WATER DISINFECTION

Watch out: also see OZONE HAZARDS

Research on Water Treatments for Odors

• Am Water Works Res, F., Bruno Langlais, David A. Reckhow, and Deborah R. Brink. Ozone in water treatment: application and engineering. CRC press, 1991.
• Camel, Vand, and A. Bermond. "The use of ozone and associated oxidation processes in drinking water treatment." Water Research 32, no. 11 (1998): 3208-3222.
• Glaze, William H., Raymond Schep, William Chauncey, Edward C. Ruth, Joseph J. Zarnoch, E. Marco Aieta, Carol H. Tate, and Michael J. McGuire. "Evaluating oxidants for the removal of model taste and odor compounds from a municipal water supply." Journal (American Water Works Association) (1990): 79-84.
• Glaze, William H., Joon-Wun Kang, and Douglas H. Chapin. "The chemistry of water treatment processes involving ozone, hydrogen peroxide and ultraviolet radiation." (1987): 335-352.
• Glaze, William H. "Drinking-water treatment with ozone." Environmental science & technology 21, no. 3 (1987): 224-230.
• Hwang, Yongwoo, Tomonori Matsuo, Keisuke Hanaki, and Noriyuki Suzuki. "Removal of odorous compounds in wastewater by using activated carbon, ozonation and aerated biofilter." Water Research 28, no. 11 (1994): 2309-2319.
• Kim, Youngsug, Yeongho Lee, Chai S. Gee, and Euiso Choi. "Treatment of taste and odor causing substances in drinking water." Water science and technology 35, no. 8 (1997): 29-36.
• Nerenberg, Robert, Bruce E. Rittmann, and William J. Soucie. "Ozone/biofiltration for removing MIB and geosmin." American Water Works Association. Journal 92, no. 12 (2000): 85.
• Von Gunten, Urs. "Ozonation of drinking water: Part I. Oxidation kinetics and product formation." Water research 37, no. 7 (2003): 1443-1467.

Peat biofilters for Odor Removal

Research:

• Zhang, Liang, Mitsuyo Hirai, and Makoto Shoda. "Removal characteristics of dimethyl sulfide, methanethiol and hydrogen sulfide by Hyphomicrobium sp. 155 isolated from peat biofilter." Journal of fermentation and bioengineering 72, no. 5 (1991): 392-396.

Potassium Permanganate or Green Sand Filters for Sulphur Odors: Oxidizing Filters

Common treatment methods use "green sand" filters or exchange tanks (potassium permanganate) or other chemical treatments, or chlorinators followed by a charcoal filtration system.

Higher levels of H₂S in the 5-7 ppm range can be successfully removed using an oxidizing filter. Oxidizing filters designed for removing hydrogen sulfide contain "green sand" or sand particles coated with magnesium dioxide (MNO₂).

As water containing hydrogen sulfide (H₂S) gas passes over the green sand particles a chemical reaction changes the gas to sulphur particles that are filtered out of the water.

To clean and re-charge the filter system it is periodically back-washed with a water solution containing potassium permanganate.

A green-sand or potassium permanganate system looks a lot like a water softener when installed but it is basically a filtration tank that contains a media specifically designed to remove sulphur odors from the water supply. There are two approaches to potassium permanganate system filters:

• Exchange Tank potassium permanganate filters: a single tank is installed through which incoming water passes to remove sulphur odors.
  
  A local water treatment service company stops by on regular intervals, usually monthly, to swap in a fresh treatment tank. The removed tank is cleaned and re-charged off-premises by the water treatment company.
• Potassium permanganate system + injector: a sulphur odor treatment tank is installed accompanied by a timer-operated chemical injection source that periodically back-washes or cleans the treatment tank and that injects chlorine or another treatment chemical (potassium permanganate or a similar chemical) to re-charge the treatment tank.
  
  This system looks much like a water softener but it is using a chemical injector rather than salt to clean and re-charge the treatment tank.

Some water treatment companies and experts recommend that a filter should be installed downstream from the greensand treatment system in order to remove any sediment or sand fine particulates that may escape the treatment tank.

Also see WATER FILTERS - SEDIMENT & IRON as the same technology is often used to remove iron and iron-loving bacteria from water.

Watch out: chemical injection systems including those used to inject potassium permanganate into the treatment equipment during backwash and regeneration contain chemicals that may be very harmful, risking burns from skin contact, or that may be toxic if ingested in their concentrated form.

Keep children away from water treatment equipment, chemical injectors, and chemical supplies for the equipment.

Using a Reverse Osmosis or RO system to remove Sulphur Odors from Water

Reverse osmosis is suitable for removing sulphur odors as well as many other contaminants from small quantities of water, such as water to be used just for drinking and cooking. Because a RO system must waste water to produce cleaned water, it's not suitable for a whole house water treatment system.

See REVERSE OSMOSIS WATER TREATMENT for details.

Shake & Wait: Free and Simple Way to Get Rid of Sulphur Odors in Drinking Water

A great way to get hydrogen sulfide reduced water to drink for free is to fill a clean milk jug three fourths full of tap water. Cover, and shake vigorously for 20-30 seconds. Remove the cover and let set on the counter for ten minutes or so, allowing time for the hydrogen sulfide you released from the water to vent out of the jug - providing you with sulfur free or reduced drinking water - at no expense!

UV Treatment to Kill Bacteria Does Not Remove Other Odors

An ultraviolet disinfection system can disinfect the water as it comes into distribution to remove bacteria within the system [but keep in mind that UV treatment does not remove any other contaminants such as particles or chemicals].

Chlorination may also be used, but is not a great choice if there is a lot of iron and manganese, as the chlorine will precipitate the metals out of solution and discolor the water.

UV Treatment is discussed in detail beginning at UV ULTRAVIOLET LIGHT WATER TREATMENT.

If it's necessary, a (more costly) cascade of water treatment equipment, installed in the proper sequence, can first remove un-wanted minerals such as iron and manganese, second, chlorinate the water to reduce bacterial levels, odors, and other chemical contaminants in water, and third, post-process the water often using charcoal filtration, to remove remaining chlorine from the water.

Research:

• Meunier, Laurence, Silvio Canonica, and Urs Von Gunten. "Implications of sequential use of UV and ozone for drinking water quality." Water research 40, no. 9 (2006): 1864-1876.
• Watts, Michael J., and Karl G. Linden. "Chlorine photolysis and subsequent OH radical production during UV treatment of chlorinated water." Water Research 41, no. 13 (2007): 2871-2878.

Water Heater Sources of Rotten Egg Smell

Two sources of sulphur or rotten egg smells traced to a water heater or water cylinder are

1. Iron in the water supply that invites iron-reducing bacterial contamination who produce sulphur odors
2. A failed sacrificial anode in the water heater whose break-down produces sulphur odors

Bacterial Contamination in the Water Heater Causes Odors

A common cause of odors from a water heater can be contamination by iron and bacteria. "Iron reducing bacteria" or as our technician called it, "iron-loving bacteria" or "ferrophilic bacteria", put simply, eat iron and excrete sulphur smells.

High levels of both iron and manganese in the water supply are likely to cause this problem.

Sometimes simply flushing the water heater tank, re-filling it, and setting the water heater to a high temperature (140°F) and leaving it that hot (and un-used) for 10 hours or longer can kill off the contaminating bacteria. The tank is then drained and re-filled and its temperature settings returned to normal.

Watch out: do not leave water heaters set to abnormally-high temperatures as you risk scalding burns of building occupants.

See SCALDING TEMPERATURES & TIMES.

We prefer to actually clean and sanitize the water heater as a more-effective solution.

See WATER TREATMENT EQUIPMENT DISINFECTION - how to disinfect water filters, water heaters, water tanks, activated charcoal systems, water softeners, sulphur treatment & other water treatment equipment.

Also see DRAIN a WATER HEATER TANK for advice on how to flush the water heater.

See WATER PIPE DE-SCALING if your water heater also has a scale problem.

Failed Sacrificial Anode in the Water Heater Causes Odors

If your sulphur odor is from the water heater, and if flushing and cleaning the heater doesn't correct the problem, changing the anode might correct the problem. A failed or badly-corroded water heater sacrificial anode can sometimes be a source of sulphur odors in the hot water supply.

Water Heater Smell Diagnosis Tip: You might diagnose the water heater as the sulphur odor or rotten egg odor source by noticing that odors appear only in the hot water supply not in cold water.

See ANODES & DIP TUBES on WATER HEATERS.

Water Softeners to Remove Sulphur Odors

Water softeners are designed to remove minerals from water, such as calcium or magnesium that make "hard" water. Water softeners work on an ion-exchange principle. Water is passed through a treatment tank in contact with an ion exchange medium in the tank.

Typically salt or sodium ions are exchanged for calcium and magnesium, and a separate salt tank is used to generate brine that in turn is used to periodically clean and re-charge the ion-exchange tank.

Many water softeners will also handle low levels of sulphur odor as well as removing low levels of iron. We include iron in this discussion because some water odors are traced to iron-loving bacteria that can contaminate a water filter, water softener, water heater, or other water treatment equipment.

See WATER SOFTENERS & CONDITIONERS - topic home, for a complete guide to choosing, installing, maintaining & cleaning a water softener.

Watch out: Just be sure the odor source is not a dirty water softener salt tank!.

Bacterial or iron contamination in the water softener itself can be a source of odors. If you suspect this is a problem in your building first

see WATER SOFTENER OUTPUT COLORS DEBRIS STAINS ODORS

then see WATER SOFTENER CLEANING & SANITIZING.

Water or Well Shock Treatment to Remove Bacteria-produced Odors

Because sulphur-reducing bacteria are normal flora, or naturally occurring bacteria, you probably can't get rid of them altogether, but annual dosing of your well with chlorine bleach will help keep them at bay.

Shock chlorinating your home system may, or may not solve the problem because the chlorine might not circulate into the dead-leg area of plumbing. If this happens, just have a plumber remove that portion of pipe.

Odors in drinking water can be caused by Manganese, Iron in the water supply which in turn support the growth of foul-odor-producing bacteria such as Gallianella.

You probably can't get rid of Gallianella because they are normal flora, (naturally occurring bacteria), but annual chlorination of your well will help keep them in check.

And well shocking can correct a temporary or "one-off" contamination of the well such as might be caused by insertion of new well piping or by the misfortune of an animal falling into the well.

Watch out: Well chlorination or well shocking at the well will not correct a pesistent odor source in the water supply itself. For that condition a water treatment system is required.

Well chlorination or well shocking is explained at WELL CHLORINATION SHOCKING PROCEDURE.

These articles discuss that approach further:

• CHLORINATORS & CHARCOAL FILTERS
• WATER FILTERS, HOME USE

...

Sulphur Eliminator - Water Agitator + Filter to Remove Sulphur Smells in Well Water

Question: Can a snifter valve air volume control system remove iron and sulphur from water?

Hello I am writing about the snifter valve. Your article DRAIN BACK & SNIFTER VALVE OPERATION on why are snifter valve air volume control systems used states that the high absorption of air into the system helps oxidize and thus reduce hydrogen sulfide or perhaps iron.

But in your last email to me you said it would not. So you have me confused. Thanks for your reply. JOE (Jan 22, 2014)

Reply: - unlikely that air injection alone can cure sulphur problems in the water supply

Thanks so much Joe, I have reviewed these articles and fixed that inconsistency.

Honestly, I am sure that I added the statement to which you refer while I was reviewing research about snifter valves, but in replying to your email I simply forgot about it.

You were right, I was mistaken. However we need some clarification:

A snifter valve is only used on deep wells that are operated by a submersible pump AND that feed water into an older-style bladderless expansion tank. The snifter valve, installed in the well piping lets air into the system at each pump on cycle.

A companion vent valve installed above ground, close to the pressure tank, or in some cases ON the pressure tank, vents excess air out of the tank to keep the tank's air charge at the proper level.

A water supply system that uses a "captive air" type water pressure tank that incorporates an internal bladder does not need this automatic injection of make-up air, so will not have a snifter valve.

In fact when a plumber converts a water supply system from bladderless-tank to internal-bladder tank, s/he needs to also pull the well piping and remove the old snifter valve if one was installed. That is what was going on in my photo series about snifter valves.

So if your water system uses a bladder type tank you wouldn't have a snifter valve installed.

Finally, and here is where we need to do more research, despite the claims of the snifter valve camp, I am doubtful that air injection ALONE will cure a serious sulphur odor in the water supply. More likely we'll need to install a treatment system such as a potassium permanganate "green sand as the plumbers call it" system or a chlorine injection system, combined with filtration, or some equivalent.

Do keep me posted, and thank you VERY much for helping me out with clarity and pointing out an inconsistency on this topic.

Reader Reports that Rotten egg smell came from water tank type

Read about rotten egg smell in wells with bladder tanks. I can attest to replacing an original galvanized tank with a bladder type causing a sulfur smell that was never there before.

Terrible Had tank replaced with fiberglas tank with original type snifter system and No More Rotten Eggs - On 2020-10-01 by Tom P -

Reply by (mod) - Success with the Sulphur Eliminator to remove sulphur odors from well water.

Tom.

Thank you, this an interesting rotten egg or sulphur odour smell source report. Let's both do some research to see if we can find any authoritative source or information about this problem.

There is a product, the "Sulfur Eliminator" that says it will get rid of sulphur odors in wells. That system combines a filter with an air injection system to aerate and filter the least-agitated water that tends to collect at the top of some wells The company provides a video but little written documentation. Contact

• Email: thesulfureliminator@gmail.com
• Tel: 336-685-0712
• Web: https://wellwaterstinks.com/

OPINION: A shallow well system may draw down the entire static head when the well is in use, so I doubt that you need this product if your pump cycle draws down the whole static head in the well.

But if you notice stronger sulplhur odors in your water when the well has sat idle for a time OR if the static head in your well is sufficient in volume that it's not usually pulled down during a typical pump-on water use cycle, then this sulphur removal system may be particularly helpful in reducing that rotten egg smell in your water supply.

To understand the volume and definition of the static head in a well

See WELL DYNAMIC HEAD & STATIC HEAD DEFINITION

 

What if the Sulphur Odor is Not Coming from the Water Supply?

If the source of rotten egg smells or sulphur in your building is not traced to a water supply problem, see these related articles

• ASBESTOS in DRYWALL
• CHINESE DRYWALL HAZARDS
• METHANE GAS SOURCES
• ODOR DIAGNOSIS CHECKLIST, PROCEDURE
• ODORS, SEPTIC or SEWER
• ODORS, SULPHUR SMELL SOURCES
• SEPTIC SYSTEM ODORS - home
• SEWER GAS ODORS - home

...

Continue reading at WATER SMELLS or ODORS, OTHER or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER ODOR TREATMENTS, CURES - SULPHUR FAQs - questions and answers posted originally on this page.

Or see these

Recommended Articles

• ANODES & DIP TUBES on WATER HEATERS
• CHEMICAL ODOR SOURCES
• CHLORINATION WELL SHOCKING PROCEDURE
• PLUMBING SYSTEM ODORS - home
• SEPTIC SYSTEM ODORS - home
• WATER SOFTENER ADJUSTMENT & CONTROLS
• SULPHUR & SEWER GAS SMELL SOURCES
• WATER ODORS, CAUSE CURE - home
  • CHLORINE SOURCES in DRINKING WATER
  • WATER ODOR DIAGNOSIS - SULPHUR
  • WATER ODOR TREATMENTS, CURES - SULPHUR
  • WATER SMELLS or ODORS, OTHER
• WATER POLLUTANT SOURCES

Suggested citation for this web page

WATER ODOR TREATMENTS, CURES - SULPHUR at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER TESTING

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