Separate the water observation
If there is no emergency concern, note which fixtures have the odor and whether it occurs with hot water, cold water, or both. Do not use taste to test the water.
Record whether the odor is strongest after water sits unused, whether treatment equipment is present, and what changed after each service visit. These observations help direct testing; they do not establish that water is safe to drink.
A. O. Smith's odor bulletin describes water conditions and bacteria as possible contributors. Replacing a part alone may not address a water-system cause. A. O. Smith smelly-water bulletin.
Request the right evidence
Give the water-heater provider the installed model, anode types, dates, treatment history, and previous results. Ask whether the replacement parts were approved for the heater.
For a private well, CDC recommends testing when taste, color, or smell changes and using a state-certified laboratory. Ask the health department about appropriate local testing. CDC well-water testing guidance.
For utility water, contact the utility about the change and testing responsibility. Have a qualified water-quality professional assess household treatment or plumbing where needed.
Compare a supported correction
Ask what the findings suggest: an approved heater-side change, a professionally managed treatment, a water-supply measure, or more investigation. Identify who performs each part and how improvement will be checked.
Do not remove corrosion protection, add chemicals, or raise the heater temperature to try to kill an assumed organism. The provider must use the actual model's approved approach and protect drinking water and household scald safety.
Your next step is to gather the service history and hot/cold observations, then request one coordinated plan. Another anode deserves approval only when the findings support it.