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No hot water: what to check first

A few checks take five minutes and sometimes fix the problem. If they do not, you will at least know what to tell the plumber.

Gas water heaters

Is the gas on? If other gas appliances are also out, the problem is the gas supply, not the heater.
Is the pilot lit? Many older heaters have a small window to see the pilot flame. Follow the relight steps printed on the heater's label, and only those steps.
Pilot will not stay lit? This is often a worn thermocouple or flame sensor. It is a common, fairly cheap repair. Causes and fixes
Newer heaters with a status light flash an error code. The code chart is on the label or in the manual. Write down the code before you call.

If you smell gas, do not try to relight anything. Leave the house and call Southwest Gas from outside.

Electric water heaters

Check the breaker. A tripped breaker is the most common cause.
Reset button. Many electric heaters have a high-limit reset behind the upper access panel. It must be done with the power off. If it trips again, something is wrong and a plumber or electrician should look at it.
Only some hot water, then cold? One of the two heating elements has probably failed. That is a repair, not a replacement.

Tankless water heaters

Check for an error code on the display.
Hard water scale is a leading cause of tankless problems in Las Vegas. Many manufacturers call for regular descaling (flushing). If it has never been flushed, that may be the fix.

When to stop and call

Call a plumber if you smell gas, see water around the base, the heater is more than about 10 years old and needs a major part, or the problem comes back after a reset.

Common questions

Why do I only get lukewarm water?

On an electric tank, one heating element has often failed. On a gas tank, heavy sediment on the bottom can keep the burner from heating the water well.