Should I Turn Off My Gas Water Heater If The Water Is Off? (Potential Risk)

The convenience of gas water heaters has made them a widely used choice for plentiful and fast-response hot water. However, gas appliances may have some inherent risks, particularly if they are not well maintained. 

Gas water heaters should be turned off if the water will be off for 24 hours or longer. You should also shut off the gas while maintenance tasks or repairs to the gas lines or pilots are in progress. The main risks associated with gas-operated appliances include carbon monoxide poisoning, fires, leaks, and even explosions. 

It is important to work safely around flames such as the pilot light, and to recognize signs of needed repairs to your gas appliance. Continue reading to learn more about the types of gas water heaters and how they operate. 

Are there different types of gas-powered water heaters?

There are two different types of gas-powered water heaters: tank versions and tankless heaters. Traditional water heaters typically have a large tank where cold water enters the appliance and is heated. The hot water is then dispersed as needed through piping systems throughout the structure. 

Tank Version and Tankless Version

There is a pilot light which remains on and ignites the gas burner when the temperature of the stored water drops below the desired setting. Because the capacity of the tank varies, the temperature of the shower water may drop as the heating process cannot keep up with the water usage.

Tankless water heaters are growing in popularity. The gas burner warms water as it passes through a pipe and into the unit. The result is almost instantaneous convenience and comfort. 

The water is not stored in a tank where the heat must be maintained. A tankless water heater is a cost-effective alternative to a traditional tank. 

Many people are choosing to install tankless heaters closer to the areas where they are needed. A small heating unit close to the shower, dishwasher, or washing machine doesn’t require the extended piping systems necessary to get hot water to the desired dispersal point. 

What role does gas play in a water heater?

The main components which make up a traditional gas-powered water heater include the tank, the cold water supply tube, hot water discharge tube, gas regulator and burner assembly, exhaust flue, temperature and pressure relief valve, and tank drain valve.  

In a tank-type heater, the gas-related parts are the gas regulator and burner assembly. The gas is supplied to the pilot flame which lights the burner when the thermostat signals that the water temperature needs to be increased. 

Types of Water Heaters
Image Credits:

The regulator assembly consists of the pilot light and gas burner. A key component of the pilot light is the thermocouple, which is a small valve that converts heat to an electrical impulse. The burner heats the water in the tank until it reaches the desired temperature. 

There are two types of tankless water heaters: a whole house system and a point-of-use unit. Whole house systems are larger and serve multiple outlets efficiently. Point-of-use are preferred for apartments, tiny houses and similar applications. 

A tankless heater, as the name implies, doesn’t have the large capacity tank to hold water and maintain the temperature. It uses a heat exchanger to heat the water. Heat is transferred from the gas burner to the cold water entering the unit. 

When you turn on the hot water at the tap, a flow sensor or flow switch detects the amount of water flow. The burner is activated and the hot water is available almost instantaneously. 

The gas shutoff valve is an important safety element. In case of an emergency, or when you need to make repairs, the flow of gas can be turned off here. 

Can turning off water to the heater damage it?

Turning off water to a gas water heater is only harmful if proper precautions are not taken. Wear and tear on the water lines and valves is minimal under normal conditions. 

If repairs are being made, or the tank is being flushed, you would turn off the water. If there are weather related events, or in the case of extended non-use, you would turn off both the gas and the water. 

What are the potential risks of not turning off my gas water heater? Can my water heater explode?

Gas water heaters have some risks, but fortunately, they are limited. Generally, the risks are due to poor maintenance or faulty parts. The main risks include gas build-up, fires, leaks, and rarely explosions.

A gas water heater which doesn’t shut off can cause excess gas to build up in the home. If this should occur, a single spark could cause a destructive explosion. 

A build-up of carbon monoxide is deadly to humans. A faulty heater has the potential to release the odorless gas into the living space. 

Water heater shut off gas valve

Leaks occur in each type of water heater: tanks and tankless. The leaks may be due to age, worn parts, a buildup of sediment, or defective connections. No one wants to find a pool of water around a water heater tank, or flowing from the tankless unit. When you combine a leaky water heater with electrical appliances nearby, it is a recipe for disaster. 

Water leaks can cause a build-up of mold and other pathogens in and around the tank or the tankless unit. Mold and mildew are a risk to the health of humans and pets. Excess moisture can negatively affect the structure of the building itself.

The risks of fire, gas buildup, water damage and carbon monoxide are real. Homeowners who are diligent about routine maintenance of the appliances have a better likelihood of avoiding such risks. A professional assessment periodically is another way to reduce the risks of faulty equipment. 

Water heaters have a lengthy life, and with proper maintenance can be expected to provide years of trouble free service. As with other home systems and appliances, regular inspection and adjustments are recommended. 

My water is off-should I turn off my gas water heater?

You should usually turn off your gas water heater when your water is off. A household without water is in a difficult situation. Yet, there are instances where it happens. If you have the time and warning to prepare for the event, there are some steps to take to prevent risks such as fire, explosion, and contamination. 

In part, the decision to turn off the gas water heater may depend on the expected length of the outage. The nature of the shut off is another factor that enters into the decision. You would not have much time to respond in the case of a flash flood, but preparing for a hurricane usually has advance warning. 

Planned outages of water are not common, but they do happen. Aging water lines must be replaced periodically. Infrastructure issues are a growing problem. Usually home and business owners have a warning that the outage is happening so they can prepare. 

Turning off valve of gas water heater

Sometimes there is an emergency situation with water lines. Excavation equipment hits a water line and the main must be taken down for repairs. An automobile or truck hits a water hydrant and repairs must be made. 

When there is a weather event which is likely to cause flooding and power problems, preparation beforehand by shutting off gas (and electrical) appliances will prevent some of the major risks which happen in the aftermath of a hurricane, tornado, or earthquake. 

If you are aware of the planned outage or the emergency event, it is recommended that you turn off your gas water heater. This is not something most people want to do, in part because of the challenges of getting the heater back up and operating again, but planning and preparation may prevent the risk of an unpleasant result from water leaks, flooding, or damaged equipment. 

How do I turn off a gas water heater?

Shutting off a gas water heater requires identifying the location of the shut off valve. It is usually black or red in color. Look for it at the front of the tank near the bottom. You may have to move insulation to see the dial. Turn the dial past the ‘Pilot’ position to the ‘Off’ position.  

An extended absence from the residence or hissing coming from the water heater is a serious situation. In this instance, the gas line valve in the gas supply line should also be turned off. Turn the gas valve ¼ turn so that the level is perpendicular to the line. 

When freezing temperatures are forecast and you are planning to be away from the house for an extended period, you should drain the heater. 

Turning off a tankless heater is a similar process. The main gas shut-off valve can be identified and turned into the off position. 

Identify the location of the valves and levers in advance of an emergency situation for more safeguards. Posting the steps required to safely turn off the appliances may make it easier and faster in the event of an emergency. 


Safe operation of appliances such as (gas or electric water heaters) which make our lives easier and more comfortable is a practice that should be part of every homeowner or apartment dweller’s activities. The safety of the inhabitants relies on knowledge, an action plan, and practicing the activities. Even youngsters can be trained in safe practices.

Taking care of your appliances and systems is likely to extend their lifespan. The purchase of a house is one of the largest investments most people will make. 

Protecting the investment, as well as the health and safety of the inhabitants, improves peace-of-mind about safe practices. A hot water heater can be expected to last for many years, with proper maintenance and repairs. 

Leave a Comment