Some causes here are gas or electrical, not just a setting. If you smell gas or your carbon monoxide alarm is going off, leave the house and call your gas utility or 911 from outside. Anything past the front dial or breaker, gas valve work, or wiring inside the unit is a job for a licensed technician.
Water Heater Has No Hot Water
Four common causes, what is safe to check yourself, and when to call a pro.
The thermostat or temperature dial is set too low
DIY OKMost common
Safe to check yourself
- Check the temperature dial or thermostat setting on the front of the unit
- Check whether anyone in the house recently changed the setting
This only involves the external dial, not opening any panel or touching wiring. Raising the setting is safe to try yourself. If hot water comes back within a few hours, that was the fix.
The pilot light is out (gas units)
Pro requiredCommon
Safe to check yourself
- Look through the viewing window near the bottom of the tank for a flame
- Check whether you smell gas near the unit before doing anything else
This has its own fix path with its own preconditions. See the pilot light page below before doing anything, and stop immediately if you smell gas.
An electric heating element has failed (electric units)
Pro requiredCommon
Safe to check yourself
- Check whether the breaker for the water heater is switched to the on position, by looking at it, without touching any wiring
- Check whether you get some warm water that runs out fast, which points to one failed element rather than total failure
Testing and replacing a heating element means working inside the unit's electrical compartment. That's mains-electric work for a licensed technician.
The tank is too small for household hot water demand
DIY OKLess common
Safe to check yourself
- Check whether hot water ran out during a high-demand time, like back-to-back showers
- Check the tank's rated capacity against how many people use hot water in the home
This isn't a malfunction, it's a sizing mismatch confirmed by the usage pattern above. Spacing out hot water use, or planning for a larger tank later, is a decision you can make yourself with no repair work involved.
DIY or pro, at a glance
- The thermostat or temperature dial is set too lowDIY OK
- The pilot light is out (gas units)Pro required
- An electric heating element has failed (electric units)Pro required
- The tank is too small for household hot water demandDIY OK
When more than one cause is possible, start from the most common one above. If you are not sure which cause applies, this one is a pro job.
Not sure if it is worth fixing?
Run the numbers on repair versus replacement cost for your water heater.
See repair or replace costs for a water heaterLast updated 2026-07-03.