Smelly Hot Water

Update and bump: I finally got around to replacing the anode rod today with a zinc aluminum rod purchased on line. I took this picture of the old and new anodes:

hot water tank anodes old vs new

As you can see, the old anode is pretty much shot. When I flushed the tank out, all sorts of black junk came out. I think the iron reducing bacteria were eating the manganese chunks coming off of the rod. This water tank is only three years old, it kind of floors me that the anode rod would go so fast. A part of it is the water from the old well, which was acidic, ph around 5.5 or so. The new well water is neutral, ph is 7 so perhaps the new anode rod will last a little longer. I will have to add that the my annual check list of things to check.
Update: I investigated the hotwater heater anode today, I think I found the culprit:

corroded magnisium hotwater tank anode

I have ordered a new zinc/aluminum anode today and I will install it as soon as it arrives. In the mean time, I poured about 1/2 a cup of bleach in the open port where the anode was installed. That took care of the rotten egg smell temporarily. Getting a new anode should make the fix permanent. There is a lot of information on the web about water heaters and sacrificial anodes. The purpose of the anode is to prevent the steel tank walls from corroding. If the anode wears out, then the tank will eventually fail, leaving the home owner to replace the entire hot water tank. Most people recommend checking the anode every 3 to 5 years. The above anode is 3 years old.

Original Post:

This one has me scratching my head a bit. Our hot water is now smelly (like rotten eggs), not the cold water, just the hot water. This is a recent development which likely has something to do with the new well. Here is what I know:

  1. Our well has ferric iron (mineral iron dissolved in the water).
  2. We are using a green sand filter to remove the dissolved iron, it appears to be doing a good job (the water looks clear and does not turn brown when exposed to air).
  3. The green sand filter backwashes twice a week.
  4. The well and filter went on line about two month ago, the smelly hot water just showed up about a week ago
  5. It is only the hot water
  6. I have drained some water out of the bottom of the hot water tank, the first gallon or so came out dark, the rest came out clear.
  7. The water tank (electric) is about 3 years old
  8. The temperature is set to about 110-120 degrees

Obviously, it seems that some type of iron reducing bacteria is in the hot water tank creating hydrogen sulfide (H2S) which accounts for the rotten egg smell. But where is the iron coming from? Is the green sand filter not getting all the iron?

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6 comments to Smelly Hot Water

  • Since you had the nice dark water coming out of the water heater, I bet you have some junk still in the pipes. Mine cleared up after a while. Also, our water gives off a little stench after the filter backwashes, but not for long. It depends on how bad your water is stinking and for how long. You should probably mix a few cups of bleach into a five gallon bucket and toss it down the well. Is it a sustained stink?

  • Very stinky at first, less so as more hot water gets used, but it still stinks. I will shock the well again and see if that makes any difference.

  • Also be sure to remove those little filters (water saver thingys) at the end of each faucet. Then, turn the water on full blast and you might see some little black particles come out. Go downstairs and tap on the pipes with a wrench. That should loosen up the junk that’s in the pipes.

    I am thinking that your problem is coming from what is already in your system.

  • Joe, a plumber

    You may want to try changing the metal anode rod in your hot water tank. Sometimes the magnesium rod that comes with the tank reacts to the water and pits badly. An aluminum or zinc rod can be used instead, they cost about 20-25 dollars.

  • Brian, Pure water salesman

    Are you using a water softening system? Are you using any kind of filtration system before or after the tank? Most of the time the smell is actually coming from bacteria. You can either try to add hydrogen peroxide or Chlorine Bleach into your tank. I personally believe the best long term advise is to get your self a filtration or RO system in place after the tank. With the right set up you can eliminate the smell, taste, color and most bacteria.

    I must agree with Jay to the rescue. I believe it is coming from your existing system. I am guessing the tank. Replacing the anodes might work for a while, but if there is bacteria in the tank, it will continue to be a problem.


    I have a well [privite water supply] I removed my anode rod almost 14 yrs ago because of smelly hot water.Solved oder problem right away. I still have same water heater but know its almost time to replace it,average life is about 12 yrs. wh’s are cheap to replace a furnace or ac,I’ll take my chances removing the anode rod then smelling that nasty oder from my hot water.

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