If you notice the smell more when you have the hot water running, then the problem probably lies in your water heater. You may have to replace the sacrificial anode rod, which needs to be replace every 5 years or so. The other, more dangerous, cause of a rotten egg smell in the home is a gas leak. Manufacturers add a chemical to natural gas and propane to give it a distinctive odor, as they are naturally colorless and odorless. This smell is actually a safety precaution and it is supposed to bother you.