If the odor is in the hot water only the water heater/anode rod are the likely source. However if the odor is in the cold water as well you likely have hydrogen sulfide in your water supply.
If the water heater is the source then the information here may be helpful:
http://www.waterheaterrescue.com/pa...ooting/stinky-water-in-hot-water-heaters.html
If the water heater is the source then the information here may be helpful:
http://www.waterheaterrescue.com/pa...ooting/stinky-water-in-hot-water-heaters.html