Water heaters
No Hot Water? Causes and What to Check First
Updated · By the Keystream Plumbing editorial team · How we research
First, rule out the simple things
Check whether every hot tap is cold or just one. One fixture points to that faucet or shower valve, not the heater. Then think about demand: a tank that was just drained by back-to-back showers needs 30 to 60 minutes to recover.
Electric water heaters
Work through these in order.
- Breaker: find the water heater's double-pole breaker and reset it if it has tripped
- Reset button: behind the upper access panel is a red high-limit button; turn the breaker off before removing the panel, then press it
- No hot water at all usually means the upper element or thermostat has failed
- Hot water that runs out quickly usually means the lower element has failed
- A reset button that trips again means a failing thermostat or element; stop resetting it and call a plumber
Gas water heaters
Look through the sight glass at the bottom of the tank. No pilot flame, or no status light on newer units, is the most common finding.
- Relight the pilot following the instructions printed on the tank
- A pilot that lights but won't stay lit points to the thermocouple or flame sensor
- Check that the gas valve on the supply line is open and other gas appliances are working
- On newer units, count the blinks of the status light and compare with the chart on the label
- If you smell gas, stop, leave the house and call the gas utility
Tankless water heaters
Tankless units show an error code on the display. The usual culprits are scale buildup on the heat exchanger, a blocked air intake or vent, an ignition failure, or a flow rate too low to trigger the burner. Descaling fixes many of them, especially in hard-water areas.
Lukewarm rather than cold
Water that never gets fully hot can be a thermostat set too low, a broken dip tube mixing cold water into the top of the tank, a failed lower element, or a tempering valve that needs replacing. About 120°F at the tap is a common target.
When to call a plumber
Call when the breaker or reset trips again, the pilot will not stay lit, you see water around the base, or the unit is past about 10 years old and needs a major part. A plumber can tell you whether water heater repair makes sense or the money is better put toward a new unit.
Frequently asked questions
Where is the reset button on a water heater?
On electric water heaters it is a red button on the upper thermostat, behind the upper access panel and insulation. Turn off the breaker before removing the panel. Gas water heaters do not have one.
Why do I have hot water in the kitchen but not the shower?
The water heater is working, so the problem is at the shower: usually a worn cartridge or a stuck pressure-balancing or anti-scald valve.
How long does it take to get hot water back after relighting the pilot?
Typically 30 to 60 minutes for a standard gas tank to reheat, longer for large tanks or very cold incoming water.
Editorial note: This guide is general information for homeowners, not a substitute for an on-site assessment. Local codes and conditions vary; a licensed pro can confirm what applies to your home. See our editorial policy.
