No hot water at all
On a gas tank, the pilot may be out or the igniter or thermocouple may have failed. On an electric tank, check the breaker first, then the reset button behind the upper panel. A reset that trips again points to a failed element or thermostat. On tankless, check the display for an error code.
Hot water runs out fast
On electric tanks, a failed lower element is the classic cause: you get a small amount of hot water from the top of the tank only. Heavy sediment, a broken dip tube, or a tank that is simply too small for the household are the other usual causes.
Popping or rumbling
Sediment on the bottom of the tank. Water trapped under it boils in small bursts. Flushing helps if it is caught early. See water heater maintenance.
Rotten egg smell from hot water only
Often a reaction between the tank's anode rod and the water. If it is in both hot and cold water, the source is the water supply, not the heater. If you smell gas near the heater, leave and call your gas utility or 911 from outside.
Rusty or brown hot water
If only the hot side is discolored, the inside of the tank may be corroding, especially if the anode is used up. A flush tells you if it is sediment or rust. Rust that keeps coming back usually means the tank is near the end.
Water around the base
- Dripping from the relief valve pipe: Pressure or temperature is too high, or the valve is worn. Do not cap it. This can mean a failed pressure reducing valve or a dead expansion tank.
- Leaking at a fitting or the drain valve: Usually repairable.
- Leaking from the tank itself: The tank has failed. Shut off the water to the heater and plan on replacement.
How old is it?
InterNACHI lists a conventional water heater at 6 to 12 years (InterNACHI). The manufacture date is coded in the serial number on the label. An older tank with any of these symptoms is a candidate for planned replacement instead of repair.