Latest Discussions : Plumbing


02:21PM | 07/12/04
Member Since: 07/11/04
3 lifetime posts
Hello. I am moving into a new-to-me home and realized that the water smells like rotten eggs. I think it might just be the hot water, but I haven't been back in the house to verify this. I saw this response to an earlier post on this forum:

"Just a wild guess, but if your new hot water heater has a magnesium anode, that can be the cause of hydrogen sulfide smells. An aluminum anode does not seem to cause the problem in systems with sulfur. Aerating the system or replacement of mangnesium anode with aluminum may help."

And...I found this website

which states: "Most hot water heaters have aluminum anode rods. If your hot water is giving off a rotten egg smell, the easiest solution is to replace the aluminum anode rod with a non-aluminum anode rod, such as the A.O. Smith KA90 or State Industries Replacement Kit, #9000029."

So, if the problem is in the hot water heater (which I really hope it is...), which is correct, using an aluminum anode rod or non-alum anode rod to get rid of the smell????

thanks, parsleygirl


03:26PM | 07/12/04
Member Since: 07/01/03
549 lifetime posts
I posted the line you quoted. There are numerous websites that talk about this issue (most of them must be plagerized, because thay all say the same thing, the same way). Magnesium seems to aggrevate the problem with sulfur bacteria and an aluminum rod is recommended. The web site you referenced surprised me,and recommends:


**If your hot water is giving off a rotten egg smell, the easiest solution is to replace the aluminum anode rod with a non-aluminum anode rod, such as the A.O. Smith KA90 or State Industries Replacement Kit, #9000029. **

Well, the State anode is an aluminum anode.

The AO Smith is a "combo rod" with aluminum, zinc and tin. Its mostly aluminum, but has other metals as well. Its certainly not magnesium. So I guess your radio host mis-spoke, because he is recommending aluminum anodes.

An aluminum anode would likely be an improvement over magnesium. This may, or may not solve the problem, but there are treatment systems that can help quite a bit.

The original thread you found I had answered is on the plumbing board here: I answered the same question here:

You scared me with this one because, I don't want to put a lot of wrong information out there, and like you, it can be found by people doing internet searches. Anyway, I'll stand by my original.

Is this new home (for you) on a well? Good luck with all. Post back for anything else you think of.

TomH Moderator


07:12PM | 07/12/04
Member Since: 07/11/04
3 lifetime posts
TomH: Thanks for the speedy reply. Most of the info I have found has been in agreement with your original advice (yes to alum anode), so I will go with that. I'll be having a plumber visit the house and it will be great to be able to ask questions to try to solve the problem from the cheapest/easiest possible solution, rather than start with full-blown water treatment. I only want to pay for that if it's necessary. Thanks for the info!



03:52AM | 07/13/04
Member Since: 07/11/04
3 lifetime posts
Yes, the water supply in the house is from a well, so it may be more than the hot water heater causing the smell.


07:53AM | 07/13/04
Member Since: 07/01/03
549 lifetime posts
Its best to address this one step at a time. Sources of sulfur tastes and smells vary. Simple aeration or chlorination systems are often effective. Once you have dealt with the hot water tank anode and discussed options with your plumber, post back and let us know what the scope of problems are and what is recommended.

While your plumber is there, ask him to do a quick evaluation of the pump, pressure gauge, pressure tank, and water softener. This will give you a top to bottom inspection, a better idea of what to expect, and how to operate those systems. The extra cost for the "tour" will be well worth savings for future trips.

Gary Slusser

07:51AM | 07/19/04
Member Since: 02/17/04
112 lifetime posts
The causes of a hot water only odor of H2S is: Sulfate is present in the water. A sulfate reducing bacteria is present in the water. This bacteria takes the oxygen off of the sulfate, making it sulfur. The anode rod generates free hydrogen in water. The hydrogen and sulfur together produces the smell (H2S).

Removing the anode rod will remove one part of the equation (voids warranty) and prevent the formation of the odor.

Draining and flushing the water heater and then sanitizing the tank with heavy chlorine kills the bacteria but usually only produces a temporary solution because more bacteria enter with the cold water. Increasing the temp to 140f will prevent the odor in most cases.

To quote Wes McGowan, excerpt taken from Water Processing for Home, Farm and

Business 1988:

When a hydrogen sulfide odor occurs in a treated water (softened or filtered), when no H2S is detected in the raw water, it usually indicates the presence of some form of sulfate-reducing bacteria in the system. These anerobic, single-cell bacteria(Thisbacilles) can exist in the piping system in the hone, especially on the hot water side. It is most noticeable on the

first hot water drawn in the morning. Water softeners provide a convenient harbor and environment for anerobic (oxygen depleted) bacterial growth.

Sulfate bacteria can derive energy by reducing the sulfate ion in the water

to H2S, and produce by-product bicarbonate in the process. Organic matter needs to be present for the bacteria to survive. However, the concentration of organics in the raw water is often below detectable levels. When this condition of H2S in hot water arises, the initial task is to heavily chlorinate the entire piping system including storage and hot water tanks.

Usually, a dose of household bleach left standing in the piping system (hot

and cold) overnight will destroy the sulfur bacteria. I has also been reported from the field that after water softeners are installed, the hot water will develop traces of H2S odor. Where softened water is fed to certain hot water heaters, this condition has been overcome by removing the anode element from the heater.


And I'll add: As we see, the water heater manufacturers can't agree as to the solution so... you can change to another type rod but that doesn't guarantee the odor problem will be solved. IMO, killing the bacteria is the only sure cure. Leaving any of the old rod in the tank as you remove it or replace one will usually allow the odor to continue.


Quality Water Associates

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