On Thursday, February 28, 2013 8:40:26 PM UTC-5, wrote:
I turned on the hot water in a house that had been empty for a while and got the worst rotten egg smell ever and it continued for 20 min till the hot water ran out. No problem with cold water. It came back after the water heated up again and this is from an electric water heater. any ideas?

It is definitely the anode rod in the water heater. Depending on the age of the heater ex. over 12 years old it may be better to replace the heater. Putting $ in a heater over 10 years old doesn't make sense as it could go bad at any time and a new one would be more energy efficient. Hope this helps..