Record the pattern
Once emergency concerns are absent, note which fixtures are affected, whether hot or cold water smells, and whether it happens after standing or throughout use. Do not taste water as a test.
Record the well, pressure tank, household treatment, recent plumbing work, and any previous sampling or heater treatment. Provide these details to the testing professional.
An odor associated with hot water directs attention to the heater and hot-water system. Odor in cold water also calls for supply-side investigation. Neither observation alone identifies the substance or confirms a particular organism.
Assign testing and equipment work
CDC recommends well testing when water's smell changes and use of a state-certified laboratory. Local health or environmental departments can advise what to test. CDC well-water testing guidance.
Have the laboratory or qualified well/water-quality professional specify sample locations, handling, and tests. A general test panel may not answer every odor question.
The water-heater provider should identify the installed model, approved corrosion protection, service history, and relevant equipment findings. A. O. Smith's bulletin identifies water conditions and bacteria as possible odor contributors, not a diagnosis of your well. A. O. Smith odor guidance.
Resolve coverage before work
Ask which proposed work is a covered equipment repair, a paid water-quality investigation, or a treatment service. Request exact parts and labor terms, exclusions, and who approves a claim.
A heater warranty does not automatically establish payment for testing, household plumbing, or water treatment. Ask for a written determination tied to the actual finding.
Your next step is to share the observation record with both the water-heater provider and testing professional. Request a coordinated source investigation and a correction whose purpose, owner, and coverage are clear.