A rotten-egg odor is commonly associated with hydrogen sulfide or sulfur-related conditions, but the odor can originate in the source water, a water heater, plumbing, or biological activity. Locating the source prevents an expensive wrong answer.
Run a simple location check
- Is the odor present in both hot and cold water?
- Does it occur at every fixture or only one?
- Is it strongest after water sits overnight?
- Did it begin after well work, flooding, plumbing changes, or water-heater service?
- Does the odor remain when water is collected in a clean glass and moved away from the drain?
Test before selecting equipment
For a private well, include bacteria, sulfur-related testing as advised locally, iron, manganese, pH, hardness, and other relevant chemistry. A qualified professional may also inspect the well and water heater.
Potential treatment categories
Depending on the confirmed cause, options may include water-heater maintenance, well disinfection or repair, aeration or oxidation, catalytic media, activated carbon, or a combined treatment train. Each option has different flow, drain, maintenance, and safety considerations.