Evidently it's fairly common. That was news to me.

I put a 30 gallon electric water heater in my shop last spring. I had no issues with it or the water for nearly six months. Then, I started to notice an AWFUL rotten egg smell coming from the hot water out there. I figured that it was just the residual of something that I had dumped into the sink and that the hot water was just vaporizing it.

Nope.

Finally, after calling my plumber and having him scratching his head searching for an answer, I called the tank manufacturer. Apparently there is a common anaerobic bacteria that lives in iron rich well water that is the cause. Their solution was to first increase the temperature to 140F+ as the bugs can't live in temps higher than that. If that didn't work, they suggest changing out the anode rods to an aluminum/zinc rod for a more permanent solution.

Interestingly I've never had the problem with the house water (I ran the line to the shop off the mainline from the well to the house). Although I have had a tankless system for the past several years, previous to that I had a gas tank heater. Never an issue...which seems odd.

The only connection to anything that I can think of is I had my well pump changed not too long before I noticed this issue. During the process, they inadvertently dumped a bunch of ironish sediment into the system. My thought is that a bunch of that sediment made it's way into the tank and allowed enough of the bacteria to start to flourish.

Talked to the folks at the county this morning and they suggest sending a sample to get tested. They have kits available in the office and this is a fairly common issue that they hear of. Again, news to me, as I've never heard of it before.

Anybody else ever experience this? Other suggestions besides what I have been advised?

There was a thread on the here on SF a couple of days ago
There is a type of anode rod that you can install to get rid of the smell

Yes, it's sulfate reducing microbes that have been around for 3.5 billion years. The magnesium anode in the water heater gives of free electrons that provide energy for rhe microbes. Aluminium anode don't corrode as fast and don't produce as many electrons.

Changing the rod itself won't get rid of the smell. Cranking the heater up to full hot for several hours will kill the bacteria. Drain and flush it afterwards. Then install the new anode. If you keep the temperature up, you don't need to replace the anode.

It's more common with units that aren't frequently used. It happened to my parents once at there winter home. My dad left the water heater off and the water reeked when they got back. From then on, they left the water heater on, hot, and haven't has the problem return.

Here's a link to an article from 1981: My water smells like rotten eggs

I'm guessing it is the aluminum/zinc rods?

I'll see if I can find the other thread. I didn't bother to search before posting as I figured that this was obscure enough to not have another thread.

That'll learn me.

Thanks for the article trapper. Interesting.

I worked for a water/sewer utility. It can happen to city water also if the temperature is not high enough and the hot water not used for a while.

Looks like I'll switch out my rods to the zinc containing ones and then bleach the shit out of the tank and flush it good.

Hopefully that'll take care of the issue.

Good Lord that is an awful smell!