Water Heaters

Hot water smells like rotten eggs (anode reaction)

Bacteria in some water supplies (common with wells) react with sulfates and the tank's sacrificial anode to make hydrogen sulfide. If only the hot water smells, the heater is the source. Fixes are an anode change to aluminum/zinc or a powered anode, plus a disinfecting shock; never just remove the anode.

Cross-checked ~90 min moderateBrands: All

Before you start

  • Turn energy OFF before draining (breaker off; gas control to pilot/OFF)
  • Electric: never power the elements with the tank partly drained
  • Removing the anode with no replacement voids tank warranties and speeds tank failure
  • Gas: do not confuse with a gas odor (natural gas/propane smell near the heater): leave and call the gas utility

Diagnostic steps

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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Hot water smells like rotten eggs (anode reaction) · OnCall Tech