Softened Water Has An Odor
Odors in water are related to the minerals in incoming water, most typically from well water. High iron content is the most likely cause for an "iron smell" in water. A "rotten egg" smell can result from hydrogen sulfide being released from iron during the softening process.
Some type of pre-treatment may be required to correct this situation. Please contact a local water specialist. You can find this information in your local yellow pages.
You can purchase a water testing kit and send a sample of your water to an independent laboratory that will do an analysis on your water and send you back a report.