How to Identify & Cure Sulphur Smells or Odors in Drinking Water InspectAPedia® -
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
What are other common odors in drinking water and what causes them?
Health risks associated with some water odors?
How to get rid of other odors in drinking water
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This article discusses how to identify, diagnose, and cure rotten egg or sulphur odors in drinking water. We also
discuss which of these odors may warn of unsanitary conditions.
If your source water runs through an area where naturally occurring sulfur is
present, some sulfur may dissolve into the water. We provide a diagnostic procedure to track down the source of sulphur smells in water just below.
Some of this dissolved sulfur turns to the gas, hydrogen sulfide, and this can
give the water a rotten egg type smelly odor.
Sulphur odors can also be caused by a failing hot water heater component, or by certain bacteria in the building plumbing system, conditions we also discuss below.
Sulphur smells in water can also occur in rivers, lakes, streams, ponds, and can be caused by anoxia and algae which in turn may be caused by high nitrogen from agricultural runoff - a condition we discuss at WELL WATER CONTAMINANT SOURCES.
Diagnosing and Correcting Sulphur Odors in Water
Sulphur or "rotten egg" odors in water throughout a home: if your water source is picking up sulphur,
either seasonally (such as when water tables drop) or all year, you have a persistent sulphur source and the odor will
be present at all plumbing fixtures in the home, possibly appearing stronger when water has not been run for some time - but
see other versions of that clue which we discus below.
Our photograph at left, courtesy of Arlene Puentes, shows black sulphur bacteria and debris in a toilet tank in a home served by a well which was very high in sulphur.
Since the toilet is supplied with cold water we knew this was a sulfur problem in the water supply, not simply a water heater anode problem.
Sulphur odors only at certain fixtures:
In certain instances, someone in the household may complain of a sulfur odor in one part of
the home, but not any other. This is usually explained because of the presence of sulfur reducing bacteria in a "dead leg" in the
plumbing system. These bacteria are not typically pathogenic, or disease-causing, and one common type would be Desulfovibriole.
If there is a portion of plumbing that has been cut and then capped off, creating a small area of non-circulating water, or a
"dead-leg", then these bacteria can get a foothold and metabolize the available sulfur in your water - creating a strong odor from
one particular sink or tap.
Sulphur odors from water heaters: A frequent source of a sulphur-like odor in home water systems, regardless of whether your water is from a private well or from a
municipal supply source, is a deteriorated sacrificial anode on the water heater tank. This anode, usually inserted into the water
tank from its top, is intended to reduce water tank corrosion. Sacrificial anodes on water tanks can be replaced. If the odor is
present only in your hot water, ask your plumber to try replacing the anode.
We discuss the hot water tank sacrificial anode and dip tube in more detail at Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank.
Hydrogen sulfide release from hot water:
Another source of sulphur odors in water the energy which water heaters add to water in the form of heat.
Increasing the temperature of water will also facilitate the release of hydrogen sulfide.
In addition, the simple act of running water at a shower or faucet will cause a release of this
sulfurous odor because of the agitation of the water being released from the tap.
Manganese, Iron, and Gallianella bacteria as a water odor source:
If your source water is high in iron and or manganese, then you may have odors that emanate from bacteria like Gallianella.
These naturally occurring bacteria can feed from the available stream of iron and manganese in a water supply,
creating foul odors and sometimes plugging, or bio fouling water filters and well.
A BART, or Biological Activity Reaction Test can determine if this type of bacteria is present in your water supply.
You probably can't get rid of them because they are normal flora, (naturally occurring bacteria), but annual chlorination
of your well will help keep them in check.
An ultraviolet disinfection system can disinfect the water as it comes into distribution
to remove bacteria within the system.
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.
Water Softeners as a source of rotten egg smells in water: if your source water from an outside spigot of un-treated water at your building does not smell, but if all of the water in your building, both hot and cold, smells like rotten eggs or sulphur, and if you have a water softener installed, it may be that you need to sanitize your water softener equipment. This problem is more likely to occur if the water softener has been shut down for a week or more, such as when you are restoring a winterized building to service. See SOFTENER ADJUSTMENT & CLEANING for the procedure to follow for sanitizing a water softener.
Other sources of sulphur odors: Does your water smell when you return from vacation?
Non-use of a regular water line can also create the same condition of sulphur odors.
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Scott Bradley, author. Scott Bradley is Laboratory Director for Aquacheck Laboratory, Inc. PO Box 87 05151 1-800-263-9596.
A more brief version of this article appeared in Aquacheck Laboratory's Water Wisdom Tips and Newsletter, Issue # 6, 2007. www.Aquacheck-VT.com offers other water supply tips in its Water Wisdom section.
The laboratory also provides water test kits and offers a free newsletter.
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