Start with what kind of heater you have
| Type | Where to look first | Common cause of no hot water |
|---|---|---|
| Gas tank | Pilot light, gas control, thermocouple | Pilot out or worn thermocouple |
| Electric tank | Breaker, reset button, thermostats | Tripped breaker or failed element |
| Tankless | Display error code, inlet filter | Scale, flame sensor, vent or gas supply |
| Heat pump hybrid | Display, air filter, mode | Mode set wrong or blocked airflow |
If you are not sure what you have, look at the label on the unit. It lists the fuel, the capacity and the model number.
Safe checks for a gas tank
Check the gas control
Make sure the knob is on and not set to pilot.
Look at the pilot
If the flame is out, follow the label's relight steps.
Smell for gas
If you smell gas, leave the house and call the gas utility or 911 first.
Try once, then call
If the pilot will not stay lit, the thermocouple or gas valve may be bad.
Do not repeat relighting attempts. A pilot that will not stay lit is telling you a part has failed. Our water heater repair page explains the diagnosis.
Safe checks for an electric tank
- Check the breaker. A tripped breaker is the easiest fix.
- Press the red reset button on the upper thermostat panel, with power off first.
- Check that the thermostat is set above the lowest setting.
- Do not open panels with power on. Call us if the breaker trips again.
A repeat trip means a shorted element or wiring problem. Resetting it again and again is a fire risk.
Tankless units
A tankless heater shows a code on its display. Look it up in the manual. Many codes point to a dirty inlet filter, low gas pressure, a blocked vent or scale. Cleaning the inlet screen is something many homeowners can do. Descaling and gas work are not. Our tankless page covers the maintenance side.
Lukewarm or runs out fast
Sediment in the tank
A flush can restore capacity if the tank is sound.
Broken dip tube
Cold water mixes into the hot supply at the top of the tank.
Failed lower element
On electric tanks, only the upper element works, so you get a short supply.
Mixing valve or crossover
A fixture or valve may be mixing hot and cold.
Stop and call when you see these
- Water around the base of the tank.
- A gas smell.
- Rumbling or popping from the tank.
- Rusty water from only the hot taps.
- A relief valve that discharges.
A leaking tank cannot be repaired. Our replacement page covers the same-day path.
Temperature settings and scald safety
A tank thermostat set too low gives lukewarm water, while one set too high is a scald risk, particularly for children and older adults. Many manufacturers suggest a moderate setting, and the label on your unit gives its recommendation. Check it before you raise the setting.
If you adjust a gas control, wait several hours before judging the result, because a tank takes time to recover. If water is still lukewarm the next day, the issue is not the dial, and it is time to call.
Why manufacturer guidelines come first
Every water heater label lists the maker's instructions for relighting, resetting and setting the temperature. Those guidelines override anything you read online, including this page, because they are written for your exact model. If the label is missing or unreadable, the model number on the rating plate lets you find the manual.
Installation standards, including the California Plumbing Code, which is based on the Uniform Plumbing Code (UPC), set the safety devices around the tank. If any of them are missing, mention it when you call.
Pleasant Hill: code items and your supplier
The City of Martinez publishes a water heater handout that cites California Plumbing Code items such as seismic straps, a relief valve drain ending 6 to 24 inches above the ground and a gas shutoff valve beside the unit. If your heater lacks them, a replacement is a good time to add them.
Contra Costa Water District serves part of Pleasant Hill, and your bill names your provider. If you see mineral crust on fixtures, ask your provider for its water quality report instead of guessing at hardness.
See the Clayton page and the Concord page for neighboring areas.
Local questions
Common causes are a pilot that is out, a tripped breaker, a failed element or thermostat, or scale in a tankless unit.
Only if there is no gas smell and no water around the unit, and you follow the label.
A shorted element or wiring problem. Do not keep resetting it.
Sediment, a broken dip tube or a failed lower element.
A leaking tank or an old tank with repeated repairs is a candidate for replacement.
Still have a question about your situation? Call (855) 575-2890 any hour and describe what you are seeing.