No hot water from the water heater

When every tap runs cold, the cause is at the water heater: a tripped breaker on an electric unit, a pilot that went out on a gas unit, or a heater that is wearing out. Start with safety, then the fuel type.

Also searched as: water heater no hot water, water heater not heating, water heater pilot light won't stay lit, water heater not heating reset button.

Before you start. If you smell gas, leave right away. Do not turn lights on or off or use a phone inside. Call 911 and your gas utility from a safe distance outside.

A residential water heater in a garage with a puddle of water at its base

Every question and answer on this page, in order

Question 1: Do you smell gas, a rotten-egg odor, near the water heater or anywhere in the house?

Yes, or I'm not sure: Leave now: possible gas leak
No: go to question 2

Question 2: Is the water heater gas or electric?

The data plate on the side of the tank says. A gas heater has a gas line and a vent pipe on top; an electric one has a heavy electrical cable instead.

Gas: go to question 3
Electric: go to question 4

Question 3: Look through the small window near the bottom of the heater. What do you see?

No flame at all: Likely cause: the pilot light is out
A yellow or orange flame: Call a pro: a yellow flame
A blue flame, but the water still is not hot enough: Likely cause: a failing element, thermostat, sediment or an aging tank

Question 4: Check the breaker for the water heater in your panel. What do you find?

Open only the hinged panel door, never the metal cover behind it. A tripped breaker sits in the middle position or off, out of line with the others.

It is tripped: go to question 5
It is on and was never tripped: Likely cause: a failing element, thermostat, sediment or an aging tank

Question 5: Reset it: switch it fully off, wait 20 seconds, then back on. Does it stay on?

Yes, it stays on: Likely cause: a tripped breaker
No, it trips again: Call a pro: the breaker will not stay on

Possible results

Need the words for the phone call? Build a what-to-tell-the-plumber checklist, or read when to call a plumber.