Safety: Turn off power (electric) or set gas control to pilot/off before servicing.

Adjust thermostat: Set to 120–130°F and allow several hours for full recovery.
Check elements (electric): Test both upper and lower elements for continuity and replace any failed elements.
Inspect burner (gas): Have a technician clean the burner and orifice if the flame appears weak or uneven.
Flush tank: Drain several gallons from the drain valve to remove sediment. For heavy buildup, perform a full flush.

State water heater: water not hot enough or lukewarm.

Possible Causes