You should have your water tested to be sure there are no contaminants,particularly if it's well water. If there are none, clean the tap and/or try a water filter.
If it's the toilet I can help you out. The water can smell from forgetting to flush and then leaving it for a while when it's hot out. Clean your toilet with bleach or a good toilet cleaner. If it's the shower, replacing the shower head can help your problem.
If you are on municipal water system let them know. Have your hot water heater checked. If your water source is the problem you may need a filter system.