Water Heaters

Rusty or brown water from hot taps only

When only the hot side is discolored, the tank is the likely source: a depleted anode rod that let the tank start corroding, rusty sediment, or (on wells) iron/manganese or iron bacteria. Check the anode before condemning the tank, but rust from an old tank lining usually means replacement.

Cross-checked ~60 min moderateBrands: All

Before you start

  • Turn off gas (pilot setting) or power before draining.
  • Hot water scalds: let the tank cool or drain carefully.
  • Gas valve and burner work is blocked: refer to a licensed tech.

Diagnostic steps

Unlock all 5 steps with expected values

Full library + AI assistant for $34.90, one time.

Get lifetime access

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.

More water heaters guides

Guide · Water Heater

Heat-pump (hybrid) water heater: slow recovery, noise, errors

Hybrids need enough room air and a clean air filter, a working condensate drain and the right mode. Many complaints are mode settings or a dirty filter. Refrigerant faults are sealed-system work.

5 steps ~60 minmoderate
Guide · Water Heater

Tankless water heater descaling (flush)

Scale insulates the heat exchanger, causing overheat codes and fluctuating temperature. Flush with a pump and descaling solution through the isolation valves.

5 steps ~75 mineasy
Guide · Water Heater

Hot water recirculation pump problems

Check timer/settings, check valves, air in the loop and the pump itself. On tankless units with built-in pumps, a recirculation code may point to air or a leak in the loop.

5 steps ~60 minmoderate
Rusty or brown water from hot taps only · OnCall Tech