Will You Have Hot Water During a Power Shutoff?

Will my water heater work during a power shutoff?

It depends on which kind you have, and that is worth finding out now rather than in the dark. Walk out to the heater before the next Red Flag warning and look at it.

A gas tank heater with a standing pilot keeps running. The pilot stays lit, the gas valve is mechanical, and nothing in the sequence needs the grid. That is the one setup in a California home that shrugs off a shutoff.

A gas tank with electronic ignition or a power vent will not run. Neither will an electric tank, because no power means no elements. Bradford White puts it plainly: any water heater that requires external power to operate will not be able to provide hot water.

A gas tankless unit does not run either. That one surprises people most, because they think of it as a gas appliance.

Why does a gas tankless heater need electricity?

Because the burner is not lit until the unit decides to light it. Tankless heaters use direct spark ignition and a control board that reads water flow, inlet temperature, and outlet temperature many times a second. Cut the power and the board goes dark, so the spark never fires. Rinnai states it directly: if you experience a power outage, your Rinnai tankless water heater will not operate.

That is not a defect. It is how every modern condensing unit works, and it is the trade for the efficiency and the hot water that does not run out.

What happens if you are on a well?

Then the problem is bigger than hot water. No power means no well pump, which means no water at all once the pressure tank empties. Depending on tank size that is usually a few toilet flushes and one short shower, not a day of normal use.

Plenty of properties out past Bennett Valley, along Sonoma Mountain Road, and through west county run on wells, and the same goes for Nicasio and the land out toward Point Reyes. If that is you, fill drinking containers when a shutoff is announced, and fill a bathtub for flushing. Sonoma County's power shutoff page covers food, medication, and cooling centers, but it says nothing about water, which is a real gap if your water comes out of the ground.

What to do before the power goes out

• Identify your heater type now: standing pilot, electronic ignition, or electric.
• Run the dishwasher and the laundry before the shutoff window starts.
• Take showers early. A full 50 gallon tank holds usable hot water for most of a day if nobody draws on it.
• On a well, fill drinking containers and a bathtub.
• Know where your main water shutoff is, in case something fails while the power is out. Our guide on how to shut off your water main walks through it.

What to check when the power comes back

Most equipment restarts on its own. A few things do not.

• Standing pilot out: relight it following the label on the tank. If it will not stay lit, the thermocouple is usually done, and that is a $150 to $250 repair.
• Electric tank: check the breaker, then the reset button on the upper thermostat.
• Tankless showing an error code: cycle the power once. A code that comes back needs a look.
• Still cold an hour after power returns: work through the checks on our no hot water page.
• Any smell of gas: leave the house first, call PG&E, then call our emergency plumbers at (707) 308-5599.

Is a battery backup worth it for a tankless heater?

If you lose power every fire season, yes. The electronics on a tankless unit draw very little, so a battery backup sized for the heater runs the controls through a multi day outage. Rinnai sells one built for their units, and other brands have equivalents. A generator solves the problem along with everything else in the house and costs a great deal more.

For scale, we install gas tankless units at $4,500 to $9,000 and standard tanks at $1,800 to $3,600, so a few hundred dollars to keep the tankless running is straightforward math. The full breakdown is in our water heater replacement cost guide.

If you are shopping for a new heater and outages are your main worry, a standing pilot gas tank is the simplest answer, though it gives up some efficiency. Call us at (707) 308-5599 and we will tell you straight which one fits your house. We handle water heater repair and installation across Sonoma and Marin County.