How Long Can You Leave a Water Heater Turned Off?

By Missy Nolan

April 15, 2025

Planning a well-deserved vacation? Travel and lodging fees can rack up quickly, so you might be tempted to turn off your water heater to save a few bucks. You may also wonder how long a water heater can sit unused during a long-term hospital stay or major home renovations.

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Some homeowners notice slight savings in these situations, but the risks may outweigh the benefits. Get the facts about long-term water heater shutdown below before you decide what to do.

Should I Turn Off My Water Heater If I Go on Vacation?

Water Heater Vacation Mode

Water heater shutdown is often unnecessary unless you're traveling for months at a time. Instead, consider using the water heater vacation mode feature. Vacation mode helps reduce energy usage and protects your home's pipes from freezing or bursting. You can often find this setting on your water heater's control panel or temperature dial. If you don't have vacation mode, consider setting your water heater to the lowest temperature on the dial.

Legionella Bacteria

Your water remains warm enough to thwart some bacterial growth in vacation mode, but Legionella bacteria can still form. Vacation mode settings vary, but your water heater may be set at approximately 50 degrees F (10 degrees C). Legionella thrives between 77 and 113 degrees F (25 to 45 degrees C). This harmful bacteria can form in water heated below 120 degrees F (45 degrees C).

After disabling vacation mode, it's important to let your water heater reach temperatures above 120 degrees F (45 degrees C) before using your home's water supply again. Otherwise, your family may be exposed to Legionella or other harmful organisms.

How Long Can a Water Heater Be Turned Off Safely?

Some homeowners turn their water heaters off for weeks or even months. But is it safe to turn off a water heater for long periods?

Safety for long-term water heater shutoff depends on several factors, including:

Weather. Pipes may freeze during cold weather if you disconnect the water heater.
Water heater shutdown process. Depending on the type of water heater you have, you may need to turn off the gas or electricity first and then turn off your water supply. Plumbing fixtures or pipes may leak if you leave the water connected.
Proper safety techniques after restarting the water heater. When you restart your water heater, you must wait several hours before using the heated water. This gives the water heater time to reheat water to a safe temperature. Otherwise, you risk exposure to illness-causing bacteria in your water supply.

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What Happens If a Water Heater Is Off for Too Long?

Legionella bacteria and other unwanted organisms can form in your plumbing system or water heater if the system remains off too long. Water heaters are generally kept at high temperatures designed to kill harmful organisms.

Heating components can also become damaged with frequent water heater shutdowns. Water heaters rely on heating elements that transform energy into heat, warming your home's water supply. These heating elements have a limited lifespan. When you turn off the water heater more than necessary, it can damage these parts. Many plumbers recommend utilizing vacation mode during trips rather than shutting off your water heater.

What Happens When You Restart a Water Heater That Has Been Turned Off

When restarting a water heater, power on your circuit breaker and water supply. Turn the temperature dial to at least 120 degrees F (45 degrees C) to kill harmful bacteria. It takes time for your water heater to reach this temperature, so wait a few hours before bathing or drinking tap water. Once the water is hot, you may need to flush your water supply by running the faucets for a few minutes. This helps remove sediment that may have built up in your water heater.

Electric water heaters often have a reset button. If you have a gas water heater, you may have to relight the pilot light. You can do this by pressing the ignite button or using a match. Check with your plumber if you're unsure how to light the pilot or reset your electric water heater.

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