Start with one simple test
Run cold water at an outdoor spigot or another fixture that bypasses the water heater. If only hot water smells, the heater is the more likely source. If hot and cold water smell at multiple fixtures, the source may be the well, pressure tank, or plumbing system.
Important: Do not rely on odor alone to decide whether water is safe. Odor-causing compounds and health-related contaminants are different questions.
Three common sources
- Hydrogen sulfide naturally present in groundwater
- Sulfur bacteria growing in a well, plumbing, or water heater
- A reaction involving the water heater's anode rod
What to do next
Arrange laboratory testing before buying treatment equipment. Test choices should reflect local geology and the symptoms you observe. A qualified well or water-treatment professional can then size treatment for the measured concentration and household flow rate.
- Document whether the odor affects hot water, cold water, or both
- Note whether it is strongest after water sits overnight
- Use a certified laboratory for health-related testing
- Ask for treatment proposals tied to actual test results