The Best Electric Water Heater in 2021: Buying Guide & Reviews

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Today’s article is a buying guide to give you everything that you need to know when picking the best electric water heater for your home. We have also picked out several great electric-running water heaters in the review section for your consideration.

Best Electric Water Heaters in 2021

How Does an Electric Water Heater Works

The working principle of an electric water heater is relatively simple.

Cold water is fed into the unit through piping. There, it is heated up by the combined action of the heat exchanger and heating elements.

The heating elements are the components inside a heater that directly produce heat. In electric heaters, the heating elements are heater coils similar to the ones you would find inside a hot plate. When an electric current runs through the coils, electrical resistance makes them piping hot.

This is where the second component, the heat exchanger, kicks in. The exchanger facilitates the transmission of heat from the heating elements into the water. The result is a welcome hot water stream for your shower and your faucets on colder days.

The Different Types of Electric Water Heaters

There are two types of electric heaters: storage and tankless. Both of them heat water using roughly the same principle as mentioned above. The only fundamental difference between them is how they store your water.

Storage Heater

Storage Heater

Storage heaters are the “traditional” water heater design that most people are familiar with. As the name suggests, hot water is produced and stored inside of a large-capacity, insulated water tank. Whenever you turn on your shower or tap, the heated water that you get is drawn directly from this tank.

The advantage of using a storage heater is that, since it is such a popular setup, there are a lot of available tank sizes. For small houses with only two to three people, for example, a 20-gallon tank will do the job well. In larger homes, you can upgrade to as large as an 80-gallon tank.

Installation and maintenance are more straightforward and cheaper with a storage heater than with a tankless model since it requires less integration overall. For a tankless electric heater, your entire electrical system and water piping will need to be rewired and redone in order to fit a heater in. 

Nevertheless, there are certain drawbacks. A water storage tank is usually quite big, so if you live in a small house with limited space, finding the right place to put the tank can be a challenge. Also, while their typical lifespan of eight to twelve years doesn’t sound so bad, they’re clearly at an disadvantage when compared to tankless heaters, which can last up to 20 years on average.

Last but not least, storage heaters are a little bit more dangerous to use than tankless, as pressure build-up has been known in some cases to cause the tank to explode. Such a scenario is extremely rare and can be prevented with regular maintenance by a professional plumber; however, it’s still a risk worth taking into account when you pick up a storage heater.

Tankless Heater

Tankless Heater

Instead of using an external water storage tank, a tankless heater heats the water as it passes through the unit and delivers it straight to you. So the heater will only operate when you need it, thus making it extremely energy efficient. According to the EPA, an electric tankless heater can save you 10% on the energy bill if you have high hot water demand and 24% if you only use a relatively modest amount.

The hot water production capability of a tankless heater is also continuous. You don’t need to wait for a water tank to be refilled or ration water. As long as you size your heater correctly to fit with your household demand, your hot water supply is technically endless.

Tankless heaters, as discussed, are generally safer and have better longevity than traditional heaters. Without a bulky tank, it is easier for you to find a space in your home where you can put the heating unit. Most tankless heaters are small and compact enough that they can fit inside a closet or a cupboard easily.

Of course, tankless heaters aren’t without their problems: Usually, they are twice as expensive as a traditional heater with the same flow rate. 

But there’s an additional investment that you will have to make if you live in an area with hard water (water with a high concentration of dissolved minerals.) That is a water softener. While you can simply flush the storage tank of traditional heaters to clear out the scales, you really can’t do the same with a tankless. If left unchecked for too long, hard water can seriously damage a tankless heater by clogging it up or destroying internal components. The softener will help with removing the minerals to keep the heater operating at tip-top shape.

Installation is often costlier and more complicated than a storage heater, too. And unlike a storage heater, you won’t be able to service a tankless heater on your own unless you have specialized knowledge and tools to do it. Tankless heaters are much more sophisticated and demand the skilled touch of a plumber to keep it in good health. Maintenance is also a bit more expensive for a tankless than a storage heater.

When the math’s finished, most people often find the upfront costs of just setting up a tankless heater to be quite discouraging. However there are a lot of people who have seen the initial cost to be worth it, considering the high performance, reliability, longevity, and safety that they could get from a tankless heating unit.

Comparison Table

 Traditional HeaterTankless Heater
Energy efficiencyLow due to the need to pre-heat water to store in the tankHigh due to on-demand hot water production
SafetySlightly riskier to useSafer than traditional heaters
CostCheaper unit costMore expensive unit cost

How to Choose the Best Electric Water Heater


Arguably, sizing is an essential factor to consider when buying a new water heater. Sizing requires you to take into account your home’s demand and contrast it with a heater’s capacity to find the best possible heater for the home. 

The right water heater should be able to keep up with your household’s demand without either falling short or exceeding it. If the heater is under-capacitated, you will find yourself having to ration hot water. Get an oversized one and you will be wasting money on your utility bill. Water heating accounts for 15.5% of the average household budget, so the extra figures can add up.

There are two factors that you must consider while sizing your heater. The heater’s flow rate (and for storage heaters– the recovery rate) and the temperature rise.

Flow rate refers to the volume of water that your heater can produce at any given time. For example, a flow rate of 1.5 GPM means that your heater can produce 1.5 gallons of water per minute. In order to find the most optimum flow rate for your household, go around the house and take into account all of the appliances that will be using the water (faucets, taps, showerheads, etc.) and add them up. The final answer will tell you how much your heater will have to produce to keep up with your entire house.

The other thing is temperature rise (or ΔT.) This refers to the temperature that your heater will have to raise the water to so that it can fit your preference. In other words, it is the difference between the water temperature that you want and the temperature of the water coming into the unit.

In the U.S, groundwater has an average temperature of roughly 57°F and most people prefer to keep their tap water in the range of 110 to 120°F. In this case, the temperature rise will be between 53 to 63°F.

Knowing the temperature rise is important because it will tell you just how efficient your heater is. The greater the difference between the groundwater and your desired water temperature, the harder the heater will have to work and the less water it can supply to different appliances in the house.

Energy Efficiency Rating

The energy efficiency of a water heater is signified by its EF (Energy Factor) rating. Calculating EF can give you the amount of hot water that an electric water heater can produce for every unit of fuel consumed. Naturally, the higher the EF, the more energy-efficient the heater is.

But you usually don’t need to bring a calculator along with you to the store to see whether it is energy efficient or not. The most economical heaters are often Energy Star-certified.

Energy Star is a program that was started by the U.S Environmental Protection Agency (EPA). It recognizes energy-efficient products with the hope of promoting more responsible energy use to help protect the environment. It’s been used for quite some time by consumers to identify and pick out energy-efficient products.

To be qualified for an Energy Star, the product must meet a minimum EF rating. A tankless water heater, for example, must have an EF of 0.67 or above.

But beware that just because it’s been rated to be energy efficient doesn’t mean that the heater is going to be cheaper to operate. Energy efficiency and cost-effectiveness are two completely separate matters. For example, electric water heaters are considerably more energy-efficient than gas heaters. But because electricity is pricier than natural gas or propane in certain regions, using an electric heater may turn out to be more expensive.


Generally, storage heaters require more regular professional maintenance than tankless heaters to ensure safety.

Most electric water heaters aren’t registered under any formal safety testing standard. So other than judging the reliability and safety of the heater unit by checking out all of its safety features, you don’t have a clear-cut way to ascertain its safety credentials. An additional step that you can take is to discuss the matter with the plumber and electrician that are going to handle the installation. They can tell you about the heater in more detail than what a brief overview in the user’s manual can provide.


Because a water heater represents a hefty investment, it is vital to keep note of the warranty information to avoid as many added expenses as possible. But the warranty information isn’t just helpful at saving probable maintenance costs in the future. Warranty information can also reveal how long the manufacturer expects the heater to last, as well as giving your plumber an idea of how often they should do maintenance checks.

Typically, a household water heater has a warranty period of 6, 9, or 12 years depending on the manufacturer.

It’s worth noting that manufacturers will typically exclude failures due to lack of proper maintenance or incorrect installation. Most warranty policies will indicate that they will warrant the water storage tank against rust, corrosion, leaks, and adverse chemical reactions. However, damage due to limescale is typically not covered.

The Best Electric Water Heater Reviews 2021

Here is a shortlist of all of the models we are covering and a comparison table with the essential details of the heaters for you to look at.

Before you read the comparison table below, keep in mind that tankless heaters’ flow rates are measured in gallons per minute (GPM). Meanwhile, traditional heaters’ flows are measured by gallons per hour (GPH).

NameFlow Rate/Recovery RateTank CapacityWarranty
EcoSmart ECO 276.5 GPMTanklessLimited Lifetime
Bosch Tronic 3000T (ES2.5)6.8 GPH2.5 Gallons6-year for heater unit, 2-year for parts
EcoSmart ECO 182.5 GPMTanklessLimited Lifetime
Bosch Tronic 3000T (ES4)6.8 GPH4 Gallons6-year for heater unit, 2-year for parts
Stiebel Eltron Tempra 36 Plus7.5 GPMTankless7-year for leakage, 3-year for parts

1. EcoSmart ECO 27: Best to Buy in 2021

As always, our selection for the “Best to Buy” category must be a well-rounded product that is balanced in every aspect: performance, reliability, aesthetics, and affordability. The EcoSmart ECO 27 fits this requirement very well as one of the best rated tankless electric water heaters on selling charts.

EcoSmart ECO 27 Electric Tankless Water Heater


  • Affordable
  • Great performance
  • High energy efficiency
  • Digital control interface
  • Durable design
  • Comprehensive warranty


  • Underperforms in cold weather

In terms of performance, the EcoSmart ECO27’s offering is among the best in its pricing range. At its maximum capacity, it can generate 6.5 gallons per minute (GPM) of hot water. To give you a better idea of this heater’s sizing, 6.5 GPM is enough hot water to feed four showerheads along with a bathroom sink. 

The performance of the heater can be affected by the weather temperature in your area. If you live in a warm area, the pipe water will already be lukewarm or moderate when it’s fed into the unit, so it doesn’t have to work a lot to bring it up to the temperature that you want. For the ECO27, the best temperature range is 68°F and above.

However, if you live in a cold area with a temperature around 32°F or below, the flow rate of the heater will be halved. Instead of getting 6.5 GPM, you can only get about 3 GPM. This is another point worth considering: if you live in a cold area, make sure to take that into account when you size your heater.

The heater’s control interfaces are modern and digitized. All of the information is displayed on a digital LCD screen at the front of the unit. You can adjust all of the settings with the array of buttons on the front. There is a standard temperature adjusting knob that you can use to change the water temperature by 1-degree increments.

 The heater also has a special computer that helps it self-regulate and achieves a 99.8% energy efficiency. Despite this impressive number, for some reason, the ECO 27 does not have an Energy Star.

When it comes to installation, you will need to work with not just a plumber but also an electrician to rewire your house’s electrical system to feed the heater. The ECO 27 requires a constant supply of 240 volts, and it has three heating elements, each of which consumes 27 kilowatts to operate. At its peak performance, the unit will have an amperage draw of 113 amps. Make sure to consult with your electrician about all of these numbers to ensure that the heater will work optimally when it is turned on.

In the case of electrical failures, the ECO 27 has overloading and overheating prevention mechanisms to protect both itself and the house. The moment it detects something going wrong, it automatically shuts itself off.

It needs surprisingly little maintenance too. You only need to install it correctly: plug it into your water system, connect it to a suitable electrical system, and store it in a dry place, and it will work well for years. The primary reason for its low-maintenance is that all of the significant components in the heater are made from durable metals like copper and stainless steel. They are rust-resistant and hardened against high temperature and pressure, so you won’t have to swap out parts now and then like with other heaters.

A limited lifetime warranty policy covers the EcoSmart ECO 27. Whenever you run into problems, you can always call them up, and they will sort everything out for you.

2. Bosch Tronic 3000T (ES2.5): Best Value Electric Water Heater

The Bosch Tronic 3000T (ES2.5) is extremely compact for an electric storage heater, which makes it a convenient point-of-use heater to fit underneath your sink or next to a showerhead. Not to mention, it is affordable and won’t break the bank if you’re looking for a low-cost water heating solution.

Bosch Electric Mini-Tank Water Heater


  • Affordable
  • Great performance for Point-of-Use
  • Simple to use
  • Compact, easy to store


  • Small capacity

Before we go any deeper into this heater’s details, we would like to highlight the fact that the Bosch Tronic 3000T (ES2.5) is a point-of-use heater. This means that it cannot supply hot water to the entirety of the house. Instead, it is only intended to generate hot water for one appliance at a time, like one bathroom sink or one showerhead—no more than that. If a whole-house electric water heater is what you’re looking for, we suggest that you look at other options.

The Tronic 3000T (ES2.5) has a 2.5 gallon integrated water tank. The tank is glass-lined and built with a layer of CFC-free insulation foam to prevent as much heat loss as possible. 

Customers state that the insulation capability of the tank is excellent. According to the specification sheet, the thermal efficiency of the tank is 98%. But it is not just thermal performance that the glass lining provides for the 3000T (ES2.5). It also makes it more durable and reduces maintenance as a result.

At a 90°F rise, the heater can gradually replenish the tank at a rate of about 6.8 gallons per hour (GPH). Time your consumption with this information in mind so that you won’t find yourself without hot water.

 The setting up process is simpler and more straightforward than whole-house heaters. It uses a standard electric cord that can be plugged into a household 120-volt outlet. The only other wiring job that you need to do is to get a water hose and plug it into the appliance that you plan on using the heater for.

The manual indicates that the heater can provide ample hot water for up to two sinks at a time, and it seems like Bosch primarily designs this heater with sinks in mind. However, customers have hooked it up to showerheads, and remark that the heater performs just as excellently.

Having a dimension of 13.75 x 13.75 x 10.75 inches, the heater is small enough to fit in a cupboard. It can be mounted on the wall or a shelf if you want to feed hot water to a bathroom’s showerhead. The small size of the heater also makes it a favorite among RV-ers and sailors who need hot water on the go as well.

This model is covered with a 6-year warranty on the unit and a 2-year warranty period for parts from the time of purchase.

3. EcoSmart ECO 18: Best Tankless Electric Water Heater

The EcoSmart ECO 18 is advertised as a mid-range water heater, and its performance reflects this marketing message well. The performance allows it to service most families of two or three with daily hot water needs. Meanwhile, offering excellent durability, usability, and ease of maintenance.

Ecosmart ECO 18 Electric Tankless Water Heater


  • Relatively affordable
  • Energy-efficient
  • Digital control interface
  • Easy to store
  • Comprehensive warranty


  • Bad cold weather performance

Just like the ECO 27, the ECO 18’s performance will be affected by water temperature. The colder the water is at your residence, the less effective the heater is going to be at producing hot water.

The ECO 18 is capable of generating 2.5 GPM at its maximum capacity and at the optimal temperature (inflow water temperature of 62°F and the heater’s outflow temperature is set for 105°F.) This flow rate will allow it to supply hot water for one full-flow showerhead. For best usage, we recommend using a water-saving showerhead rated for 1.5 GPM, and the excess hot water flow can be used to run an additional bathroom sink.

The heater has a digital screen that displays relevant information and the current temperature setting. There is a knob that allows you to change the temperature by 1-degree increments. ECO 18 is also equipped with an automatic computer to control energy efficiency, clocking in at 99.8%. However, just like the ECO 27, it does not have an Energy Star.

The electrical requirements are a little bit lighter in comparison to the ECO 27. The maximum amperage draw of the ECO 18 is 75 amps, and the heater works on a 240-volt grid. It’s got three heating elements, each of which uses up 9 kW per factory setting. However, you can adjust this number in the settings accessible through the heater’s control panel.

Make sure that your electrical grid is up to date before you start up the heater (for that, consult with your electrician as well as your plumber.)

The heater is covered under a limited lifetime warranty policy. Specifically, on the electronics, exchanger, and the heating elements. The warranty card mentions that in case of labor or incidental damages, the warranty is voided.

4. Bosch Tronic 3000T (ES4): Best Small Electric Water Heater

While the 2.5 gallon version is far smaller and more compact, we think that 4 gallons is a perfect match for most small household needs. You will get the durability and longevity, as well as the performance to boot.

Bosch Electric ES4 Tronic 3000 T Mini-Tank Water Heater


  • Affordable
  • Great performance for Point-of-Use
  • Simple to use
  • Compact, easy to store


  • Small capacity

Even though the tank capacity is larger, it is still wholly a “point-of-use” water heater. While 4 gallons will be able to provide hot water for a complete bathroom with one full-size showerhead and a sink, you should not expect from it the kind of performance that a full-size household heater can give you. 

The internal 4 gallon water tank is covered with a layer of insulating CFC-free foam as well as glass lining. Both of these details combined give the heater a 98% thermal efficiency along with a reduced need for maintenance. The recovery rate of the 3000T (ES4) with a temperature rise at 90°F is 6.8 GPH.

The overall dimensions of the design still give it a very compact profile and small footprint. At 13.75 x 13.75 x 13.5 inches, the 3000T (ES4) will always be able to fit inside small cupboards and underneath sinks or counters. If you’re an RV-er or sailor wanting to have hot water on your boat, it will still be relatively easy to find a good space to put the heater unit in your place.

The 3000T (ES4) is a plug-in heater, meaning it comes with a standard electrical cord that you can plug into any 120-volt outlet, and it will begin its job without fuss. Just attach it to a water system, and you will have hot water in no time at all.

The entire unit has warranty coverage for six years. For parts, you have two years from the date of purchase.

5. Stiebel Eltron Tempra 36 Plus: Best Whole House Electric Water Heater

The Stiebel Eltron Tempra 36 Plus has raw performance on its side. Even though it is a tankless electric water heater, its performance puts it on par with gas-running heaters on the market. The Tempra 36 Plus also benefits from having a beautiful, compact design as well as great ease of use and maintainability, making it a great candidate for a whole house electric water heater.

Stiebel Eltron Tempra 36 Plus Water Heater


  • Exceptionally powerful
  • Highly energy-efficient
  • Digital control interface
  • Various safety sensors
  • Great warranty policy


  • Expensive unit cost

At optimal water temperature (above 72°F), the heater can generate a steady flow of hot water at 7.5 GPM. With this flow rate, you can run about four water-saving showerheads (1.5 GPM each) as well as two bathroom sinks simultaneously. But even if you live in colder areas with water temperature below 42°F, the Tempra 36 Plus will still have enough performance in it to supply two showerheads and a sink.

It has a near-absolute EF rating at 0.99 thanks to the computer packed inside that can automatically adjust the heater’s energy consumption. Nearly all of the electricity that the heater unit draws will be used to heat the water or run the heater’s system. This will save you a hefty amount on the utility bill at the end of each month.

The Advanced Flow Control function inside the computer can keep the water temperature constant (eliminating the sudden shifts in water temperature commonly seen in other heaters.) It will also reduce water consumption too, which is another cost-saving method.

For best operation, the heater must be plugged into a stable electrical grid running 240 volts. All of the heating elements combined use 36 kW and have a maximum amperage draw of 150 amps.

The controls are digitized with a display screen that shows you all of the essential data like the water temperature and power information. There’s a temperature adjusting knob for you to alter the temperature setting. Memory buttons are available to set the preferred temperature for the entire family. Program the settings you want to one button and pushing it will automatically switch the heater to the desired settings without requiring you to go through all of the complex set-ups.

From the date of purchase, the heater has a 7-year warranty period on leakage and a 3-year period for parts.

How to Properly Maintain Your Electric Water Heater

Even though water heaters are designed to be reliable for decades, you can reduce maintenance costs and the stress on the heater by doing the few simple steps below.

Lower Your Thermostat

Heaters are often programmed from the factory to have a default temperature setting at 130°F. However, just ask any plumber, and they will tell you that the best temperature to set your heater at is from 115°F to 120°F. This will not only save you as much as 5% on the utility bill, but it will also reduce the risk of the unit becoming overheated.

Additionally, you won’t feel that much of a difference in warmth between 130°F and 120°F.

Check the Pressure Relief Valve

This is an important step to take if you have a storage heater. If the pressure relief valve doesn’t work correctly and vent excess pressure, the heater can explode. Fortunately, you can check whether your heater’s valve is working or not reasonably easily without needing to call a plumber.

Consult your user’s manual and find the relief valve. Once you do, turn the valve halfway up and let it snap back into place. Listen carefully to the sound that the heater makes. If it makes a gurgling sound, then the valve is working correctly as it is sending excess water back into the drain. If you hear nothing, chances are, the valve has malfunctioned, and you should contact your local plumber immediately for them to check it out and replace the faulty valve for a new one.

Flush the Heater

Mineral scales can build up inside the heater or water tank after using for a while. These solid masses of condensed minerals can destroy the tank and reduce the heater’s performance. Flushing the tank and the heater can help a fair bit with removing these harmful clogs.

Shut down the heater and remove it from the power, use a circuit breaker if you can for safety reasons.

After that, put an empty bucket underneath the drain valve (you can check the user’s manual to see where it is.) Alternatively, if you have a water hose you can use, connect it to the drain valve, and lead the hose somewhere safe outside of the house.

Turn the valve counter-clockwise to open it up. Keep in mind that the water coming out can be extremely hot, so keep as much distance as possible and be careful.

After about 1 to 2 gallons have been flushed from out of the unit, shut off the valve again by turning it clockwise.

That’s about it. You can turn the power back on and use your heater as usual.

Use a Thermal Blanket to Insulate the Heater

For the heater to be as efficient as possible, it needs to be insulated from the surrounding environment to discourage thermal loss. It will also lessen the stress on the heater because it won’t need to work as hard to heat the water. 

This is highly recommended if you live in a cold region.

One way you can do this is to get thermal blankets and wrap them around the heater unit, the storage tank, or the pipes. 

If you are unsure about anything you can send us a message, look to the user’s manual, or call your trusted plumber. 


That’s it for our buying guide and reviews of the best electric hot water heaters in 2021! We hope that you have found the information to be useful and, more importantly, found the heater that works for you!

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