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.
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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.
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.
Or for a complete guide to sources of and cures for odors in water see WATER ODORS, CAUSE CURE - home.
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.
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.
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.
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.
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.
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
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:
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.
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.
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!
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.
Two sources of sulphur or rotten egg smells traced to a water heater or water cylinder are
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.
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.
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 - 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 SOFTENER OUTPUT COLORS DEBRIS STAINS ODORS then see SOFTENER CLEANING & SANITIZING.
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:
If the source of rotten egg smells or sulphur in your building is not traced to a water supply problem, see these related articles
Continue reading at WATER SMELLS or ODORS, OTHER or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see SEWER GAS ODORS - home
Or see WATER ODORS, CAUSE CURE - home
Or see WATER TREATMENT EQUIPMENT CHOICES - home
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we have a new pressure tank with a bladder. we also have a rotten egg smell in our water. I read on your web sight that a snifter valve would eliminate that. I wonder if it would make sents to put the bladderless tank in ahead of the bladder tank. Thanks Joe ps. your wed sight is very good. - J.M. 1/18/2014
A snifter valve (SNIFTER & DRAIN BACK VALVES ) is a device that adds air to a pressure tank system where a submersible pump and a bladderless pressure tank are installed. It has nothing to do with the elimination of a sulfur odor or rotten-egg smell in water. IF the odor is in incoming cold water I agree that it's probably originating in the well, and that a treatment system may be what's needed.
I suggest taking a look at either or both of these two articles
A second question arises from your note: I don't have a clear picture of what water equipment you have installed, but it sounds a bit odd to have both a bladderless water pressure tank and a bladder tank on the same system unless the bladderless tank is a large water quantity storage system (as we might have on a well with a poor water flow rate - WATER STORAGE TANKS, LARGE).
Perhaps with more details about & photos of your system I could comment further.
(Sept 7, 2011) Doug said:
I fill water jugs and put them in the refrigerator to cool. This will rid the water of the sulfur odor. I store several and have excellent drinking water and wonderful water for tea at all times.
(July 28, 2014) Marc said:
We have dealt with sulphur smell issues in the past and always got them resolved, whether it was coming from a water heater or an isolated supply line. The situation we are now dealing with involves a new water softening unit that is in a garage (away from sunlight or heat). 1-2 weeks after install they began having the odor develop. It affects the whole house on both hot/cold supply. If the unit is in by-pass, the odor goes away. They are on treated municipal water. Any info on the subject would be greatly appreciated. Thanks
A good place to start is with the water softener that may have become contaminated (e.g. with bacteria)
for some suggestions. It may become necessary to sanitize the water heater too but try the softener first.
(Mar 15, 2015) Anonymous said:
We put in a brand new water softener for the first time because we have well water and now we have the rotten egg smell that we never had before. It gets really bad in the spring and of course is strongest in coming from the hot water. We had the well shocked and that didn't help one bit. We then had replaced the hot water tank and still smells. We are at a loss.
1. a contaminated softener or brine tank - bacteria can cause odors
2. sulphur in the water supply - take a sample ahead of all of the water equipment
3. a deteriorated water heater anode
For detailed guidance see SULPHUR & SEWER GAS SMELL SOURCES in More Reading above.
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