Most water heaters have a Vacation setting for a reason: it's the right balance of energy savings and protection. Vacation mode keeps the burner or element on at a low setpoint (usually around 50°F to 60°F), which prevents the tank from freezing in cold weather and keeps internal corrosion at bay, while cutting most of the standby energy use. Fully shutting the heater off saves slightly more energy but adds risks: a cold tank in winter can freeze, an empty tank can corrode, and an electric tank that gets powered on while empty will burn out the elements within minutes.

Quick guidance by trip length

  • Under 3 days: leave it alone. The standby savings aren't worth the fuss.
  • 3 days to 1 week: Gas: turn the gas control dial to "Vacation." Electric: drop the thermostat to its lowest setting.
  • 1 to 4 weeks: Same as above, plus shut off the cold water supply at the heater inlet valve. Reduces risk of tank or supply line failure while you're gone.
  • Longer than 4 weeks, especially in freezing climates: Drain the tank, shut off power or gas, and shut off the supply. This is more involved; consider a plumber if you're not sure.

Why not just turn it off

Three reasons:

  • Freeze risk. A heater in an unheated garage or basement that's exposed to winter temperatures can freeze if the burner isn't keeping water warm. A burst tank or supply line during a vacation = a flooded home.
  • Element damage on electric heaters. If the tank drains for any reason (drip valve, leak, demand from a faucet someone forgot to shut) and the breaker stays on, the elements will be exposed to air and burn out the moment they try to heat. Replacement is $100 to $300.
  • Bacteria growth. A cold tank that sits for weeks can grow legionella in the lukewarm zone (77-113°F). Vacation mode keeps the tank hot enough to discourage growth.

How to set vacation mode

Gas water heater

  1. The gas control valve is at the bottom of the tank.
  2. The temperature dial has marks for "Hot," "Very Hot," "Warm," "A," "B," "C," etc. There's usually a "Vacation" position to the left of the lowest temperature.
  3. Turn the dial to "Vacation." The pilot stays lit but the main burner won't fire unless the tank gets cold enough.
  4. When you return, turn the dial back to your normal setting (usually around 120°F, often marked "A" or with a star).

Electric water heater

  1. There's no dedicated "Vacation" mode on most electric heaters.
  2. Turn off the breaker if the trip is short and the climate isn't freezing.
  3. For longer trips or any freeze risk: leave the breaker on but turn the thermostat down. To do this, shut off the breaker, remove the upper and lower thermostat access panels, turn each thermostat dial down to its lowest setting (usually around 90°F), reinstall the covers, and turn the breaker back on. Inside the access panels is exposed wiring; the breaker has to be off while you're in there.

Tankless water heater

  1. Most tankless units have a vacation or away setting in the controller menu.
  2. If yours doesn't, just leave it on its normal setting. Tankless heaters use no energy when no one's drawing hot water, so vacation savings are minimal.

Should you shut off the water supply too

Yes if the trip is longer than a week. The valve is usually a quarter-turn lever on the cold inlet at the top of the heater. Shutting it stops fresh water from entering the heater if a leak develops downstream (in the heater itself, in supply lines, or in any plumbing in the house). See pre-vacation home checklist for the full water shutoff context.

When you return

  1. Confirm the cold water supply to the heater is on and the tank is full (run a hot tap somewhere in the house; if water comes out smoothly without sputtering, the tank is full).
  2. Gas: turn the temperature dial from "Vacation" back to your normal setpoint.
  3. Electric: if you turned the breaker off, turn it on. If you turned the thermostat down, reverse that (breaker off, panels open, dial up, panels closed, breaker on).
  4. Allow 30 to 60 minutes for the tank to reach setpoint before expecting full hot water.
  5. Run hot water at a faucet to flush any standing water from the lines.

What not to do

  • Don't drain the tank unless you've turned off power or gas first. Draining an electric tank with the breaker on will burn out the elements the moment they try to heat air. Draining a gas tank with the pilot lit can cause an unsafe condition.
  • Don't shut off the cold supply without also adjusting the temperature setting if the heater is in a freeze-risk space. A heater with no water inflow but power on can superheat the remaining water.
  • Don't fully shut down a heater in a freezing space without draining it. Frozen water in the tank or pipes can split things open.
  • Don't try to test or replace the T&P relief valve as part of vacation prep. T&P work is plumber territory.

Good maintenance rhythm

  • Before any trip 3+ days: gas heater to "Vacation," electric heater thermostat down.
  • Before any trip 1+ week: also shut off the cold water supply at the heater.
  • Before any trip in freezing climate: confirm the heater space stays above freezing or plan a full shutdown + drain.
  • When you return: full restart sequence in order. Don't power up an empty tank.
  • Yearly: confirm the vacation dial position still works and the shutoff valve still turns.
  • Pair vacation prep with the full pre-trip walkthrough so the water heater doesn't get forgotten.
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