Does your hot water smell like rotten eggs, even though your hot water tank is fairly new ? Don't be alarmed, it happens quite often. This can happen even if your cold water does not have a smell. Don't let a water treatment dealer sell you equipment to correct this problem. I have seen it time after time and it's a waste of money. The cause of the odor in your hot water tank is the anode rod, or referred to in the industry as the "mag rod". This anode is made from magnesium and is a self-sacrificing rod that will dissolve and help protect the tank from corrosion. This situation often occurs after a water softener is installed, even if your tank is two or three weeks old !!! Why ?? Because soft water contains sodium, and the sodium reacts with the magnesium rod because the water is more conductive and creates a bacteria that smells. This odor can be really offensive and make you not even want to use your hot water. So what's the solution ? There are a couple of ways, as I will outline below.
1. If your hot water tank is under warranty, you cannot remove the rod because it will void the manufacturers warranty. What you can do is go buy a zinc/aluminum rod to take it's place. It is attached to a plug on the top of the tank or can be attached to the hot side nipple that comes out of the tank (commonly found on Bradford White heaters) Unless you are fairly handy with plumbing or hot water tanks, I strongly recommend using a plumbing professional. It will take a breaker bar with a 1 -1/16" (inch and one sixteen) socket to remove it. They are usually installed very tight and can be hard to remove, so you will need someone to hold the tank while you are removing it. Just make sure you shut off the water first and shut off the electric(if it's electric) and take a gallon or two of water out of the bottom of the tank before you start to remove the rod. Once you have the rod out take a funnel and pour 1/4 gallon of bleach into the tank to kill the bacteria and then you can put the same rod back in or I would strongly suggest replacing with a aluminum/zinc rod. Even aluminum rods can stink from time to time. That's why it's best to buy an aluminum/zinc rod. Make sure to put some pipe thread sealant (pipe dope) or Teflon on the threads before re-installing. After you are done, turn the water back on and run a little water out of the bottom until you smell the chlorine bleach. Then go to each hot faucet, one at a time, and run the hot water until you smell bleach. Repeat this until you have done every hot faucet in the house, but make sure to do it one at a time. You will get air and black water so don't be alarmed, this is normal. After about 3-4 hours run a couple of hot faucets until the bleach is gone and repeat each faucet to flush out all of the lines to get rid of the bleach. The reason for the bleach is to kill the bacteria causing the problem.
2. If you hot water tank is OUT OF WARRANTY, go ahead and remove the rod and put a 3/4" brass plug in it's place. Make sure to use Teflon tape of pipe dope on the threads. Also, do the bleach process I have described above to kill the bacteria and resolve the problem.
From my 25 + years of experience in doing this, no other way is more effective than bleaching your hot water tank. The bleach will not hurt your tank. You have to kill the odor producing bacteria in order to kill the smell. I have search google and Yahoo for answers on this topic and I can't believe some of the solutions people have come up with. This is the only effective way I know to cure this problem. A lot of reputable water conditioning dealers usually offer this service because they run into this problem every day. Plumbers don't usually chlorinate, unless they have done this before.
Hope this helps you !
The Water Guy