Appliance Review: Gas vs. Electric Water Heater Comparison


Homeowners deciding between gas and electric water heaters ultimately need to make a determination between initial price or long-run efficiency. Either gas or electric can heat your water at home, and both offer unique advantages the other can’t match. In the end, the decision — like home ownership — is personal.

Heating Source

Gas Water Heaters
Natural gas, now cheap and plentiful, fuels conventional gas-fired heaters. The main advantage of gas over electric is that gas-fired heaters can cost far less to operate, depending on where you’re located. In California, for example, natural gas can be three times cheaper than electric. Such savings are often enough to justify the higher upfront investment relative to electric.

Another plus for gas-fired heaters is that those with pilot lights are immune to power outages. If you live in an area where electricity is expensive or unreliable, or if you simply do not want to increase your electricity bill, this decision is easy.

Tankless gas-fired models are considerably more energy-efficient than the tanked variety and also heat water faster than electric tankless heaters.

Electric Water Heaters
Electric heaters with water tanks heat more quickly, cost less upfront, are more energy-efficient and are easier to maintain than gas models. Tankless electric models are considerably more expensive, but even more efficient because they only heat water on demand, instead of storing large quantities of water that may not be used for days. On the downside, tankless electric models can take a while to reach a desired temperature, and you may need a small backup storage tank to provide hot water precisely when you want it.

Although electric heaters can cost more to operate, they offer higher energy factor ratings and are easier to maintain. They also don’t require you to endure the hassle of installing ventilation. If energy efficiency and ease of use are worth paying more, electric may be the answer for you.

Design & Functionality

A traditional storage-tank water heater is a storage tank that takes in fresh, cold water and, with a gas or electric flame at the bottom of the tank, heats the water to the temperature you desire. The tank’s layers of insulation, along with water’s natural ability to store energy, keep the water in the tank consistently hot and ready when you need it and even when you don’t. Keeping the water hot all the time can be costly and unnecessary, but useful if your demand for hot water is always high as well.

One common concern with traditional heaters is water quality. The tank is intended to constantly store large volumes of water at temperature, and unless there’s enough demand to recycle all the tank’s water in a decent amount of time, it will languish in the storage tank. This can gradually rust the tank, encourage bacteria growth, and make the water taste and smell odd compared to the fresh groundwater.

Choosing an ideal thermostat setting for a traditional heater is a critical but sometimes confusing balance between safety, water quality, and energy consumption. According to the blog Treehugger, settings below about 120 degrees Fahrenheit save energy and prevent calcium buildup, but can allow legionella to thrive. A temperature above 140 degrees guards against bacteria but will be scalding hot, can worsen calcium deposits, and will use more energy.

The principal difference between gas and electric models with storage tanks is the presence of a pilot light. Pilot lights, present in gas models only, allow you to continue heating water even during a power outage. Gas models also require ventilation, which is a nonfactor in electric heaters.

Traditional storage-tank heaters are a better short-term value and their technology is time-tested, but you may miss out on some of the modern conveniences a tankless model can offer.

Tankless heaters attempt to instantly spike the temperature of incoming groundwater to the desired level of warmth. Because they don’t have to bring an entire 50-gallon water tank to the right temperature at once, these models heat faster than traditional ones, but the lack of any hot water reservoir can mean you’ll wait a little while for the water from your tap to get warm enough.

You can reduce this problem by placing the heater as close to all your water fixtures as it can get, in a central location, so there is less cold water to push through the pipes before the warm water arrives at the tap. Another common fix is to use smaller hot water pipes, since larger pipes mean you’ll have to run a greater volume of cold water from the pipes before the running water gets warm.

If you’re a fan of long, hot showers, then tankless heaters have one huge advantage: They never run out. Since they heat on demand, they’ll continue keeping your shower piping hot as long as you like.

Tankless models are unquestionably a more costly upfront investment than traditional ones. They contain more advanced hardware, require electricity for some functions, and may call for basement reconfigurations whose costs can also run high. According to Consumer Reports, the initial cost of a tankless heater is so high that breaking even with energy savings can take longer than the heater’s functional life.

Some tankless models are gas-fired, which sacrifices some efficiency in favor of raw heating speed. If you can eat the initial investment, a gas tankless heater can overcome the speed disadvantage that plagues electric tankless models.

Drain Valves

Drain valves are often the cheapest the manufacturer can get away with: flimsy and plastic, easily clogged by sediment buildup and possibly sludge from corroded aluminum anodes. Hard water also plays a large part in clogging a valve. A functioning, dependable drain valve can save your life in a disaster that cuts off your water supply, so try to find a heater with one made of brass and during the life of the heater, make sure the valve is still working.

Tank Lining

Storage tanks for both gas and electric models are lined with glass to prevent rusting. Although no glass lining can permanently keep rust at bay, the lining is one of the main reasons that water heaters typically last 20 years. Anode rods also extend the useful lives of water heaters. These sacrificial metal rods sit inside the storage tank and absorb corrosion over time, tanking most of the burden off the storage tank’s walls. Even with timely replacement, anode rods cannot protect a tank forever.

Digital Display

Digital displays are more common in electric than gas models, since gas heaters are mechanically simpler analog machines. Tankless models, whether gas or electric, are far more likely to carry digital displays because they require a more immediate level of control.

Space Requirements

Among tanked models, electric water heaters require less space because they need no ventilation. Gas heaters need between six and 18 inches of ventilation around the sides and top, limiting installation to a few choice locations in a building. Electric heaters come in a greater variety of sizes and can be crammed into smaller areas, which could tip your hand in their favor if you’re short on space.

Tankless models, of course, occupy even less space and can easily be wall-mounted. Gas tankless models must be mounted near gas and water inputs and connected carefully, while electric models have even fewer limits on where they can be placed.


Hot water tanks come with an extensive list of safety features:

• A temperature/pressure relief valve releases tank pressure when it exceeds a certain limit.

• Mixing valves mix cool groundwater with hot water from the heater to lower its temperature just enough to prevent injury.

• Storage-tank heaters are almost always anchored to a wall to prevent the device from tipping over and breaking gas and water pipes during an earthquake.

• Proper ventilation prevents fumes from entering living areas or corroding the heater and its pipes.

• And the most obvious but easily overlooked safety feature is that what you see in the basement is not the water heater—it’s the water heater’s shell. (While the shell protects you and the heater’s interior, however, it can mask serious internal damage. If the shell is in bad condition, expect the heater’s innards to be in far worse shape.)

• Anode rods prevent aluminum from latching onto water molecules and causing serious health problems. Yet aluminum anodes are dangerous because, in an emergency, you could be using your drain valve to drink from your water heater, and harmful particles from the disintegrating anode fall straight to the bottom of the heater. Magnesium and titanium anodes don’t have this flaw.

Traditional water heaters made in 2003 or later meet the “Flammable Vapor Ignition Resistant” standard, developed to prevent heaters from igniting nearby flammable substances.

While the chances of a water heater disaster are small, they can be so catastrophic that manufacturers take every precaution to ensure they rarely happen.

Electric water heaters lack one tiny yet still present risk of gas heaters: combustion. Despite gas heaters’ extensive safety features, they still use a combustible fuel to heat your water, and combustion-related disasters cannot be ruled out. On the other hand, while natural gas and flames don’t mix, neither do electricity and water. Nothing is 100% safe, but in the worst, most unfortunate case, electric models are least likely to result in an explosion.


Gas and electric water heaters with water tanks come with a similar selection of warranties. Tankless electric models may come with shorter warranty options, but the value of a coverage plan is influenced more by your choice of manufacturer and vendor, than the heating system itself.

Additional Features

Pricier water heater models may include:

• Electrified titanium anodes that guard against corrosion without being consumed like aluminum or magnesium anodes

• Ceramic heating element to reduce scale deposits and mitigate heating noise

• Anti-scale attachments that inhibit deposit buildup

Investing in these higher-end features may or may not be necessary, depending on your situation, but as we’ve mentioned before, the water heater is not a purchase on which you’d be wise to cut corners. Investing extra can improve the quality of your water, the longevity of the device and the safety of your home. While value is always critical, do keep that in mind.


The choice between gas and electric is mostly a choice between a better initial price or superior long-run efficiency. If you care more about immediate savings on hardware, electric models carry smaller ticket prices, but your electricity bills could smash your budget during the following few years. If you’re willing to pay more and install proper ventilation, a gas model will save lots of cash down the road, especially given the falling price of natural gas. Ultimately, the choice is yours, but choose wisely—your water heater is one of those appliances on which you should never cut corners.