Best Under Sink Water Heaters of 2022

Under sink water heaters can save energy and provide instant hot water without needing to run the tap first.

Water heaters are expensive to replace and can easily burn a hole through your pocket if you don’t choose a reliable brand.

We’ve done our due diligence on under sink water heaters to help you find the best in terms of price, quality, size, and many other factors.

If you want to ensure you buy right the first time and save money, these are the best under sink water heaters you won’t want to miss out on.

Our Top Picks

Sensible Digs earns a commission through the following independently chosen links at no additional cost to you.
Product Comparison Table

Product Image of the Bosch Electric Mini-Tank Water Heater Tronic 3000 T 4-Gallon (ES4) - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted
Best for Low Hot Water Demands
Bosch Electric Mini-Tank
  • Made of glass-lined material
  • CFC-free foam insulation
  • Energy-efficient
Product Image of the EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology
Best for Energy Efficiency
EcoSmart ECO 11
  • 99.8% energy efficient
  • Patented self-modulating technology
  • Digital display & thermostat
Product Image of the Thermoflow UT10 2.5 Gallons 110~120V Corded Electric Mini Tank Water Heater for Under Sinks 110V ~ 120V, 1.5kW Point of Use
Best for Colder Regions
Thermoflow UT10
  • Frost protection mode
  • EPS foaming heat system
  • Automatic thermostop function
Product Image of the Camplux ME25 Mini Tank Electric Water Heater 2.5-Gallon with Cord Plug,1.5kW at 120 Volts
Best for Outdoor Living
Camplux ME25
  • 2.5 gal glass-lined tank
  • Heat rate of 6.8 gal/hr
  • Easy-to-use thermostat
Product Image of the Ariston GL6+S Electric Mini-Tank Water Heater
Best for High Hot Water Demands
Ariston GL6+S
  • 6+ gallon water tank
  • Easy to install
  • 6-year warranty

Why Buy an Under Sink Water Heater?

An under sink water heater is not here to replace your current, larger heater. Rather, it’s here to provide you with that extra hot water for the last few dishes.

Under sink water heaters are primarily designed to provide sufficient hot water for your smaller uses. This could be for your kitchen faucet or an extra shower. They help you save the money otherwise wasted on keeping your larger water heater going.

These water heaters are small electrical appliances that you can install nearly anywhere. Many people install one in their boat, RV, cottage, apartment, office, or garage.

You may also know them as “under counter” water heaters or “instant” water heaters. Some of the main advantages of these appliances are that they save water, energy, and space.

Keep In Mind

Under sink water heaters are not replacements for your larger unit. Either connect them directly to your sink or shower or use them in-line with your current unit.

Let’s have a look at some more benefits of under sink water heaters.

  • Fast and efficient: The average under sink tankless water heater will bring you hot water in an instant. A tank-type heater will take a couple of minutes.
  • Less environmental impact: With a hot water “on-demand” system, you’re reducing your impact on the environment.
  • Compact size: Because an under counter water heater is small and compact, you can place it anywhere in a cabinet or under the sink.
  • Easy to install: Also, thanks to its compact size, the installation cost is less — if you’re handy, you can quickly do it yourself.
  • Cleaner water: Under sink water heaters have more of a “point-delivery system.” So there’s less chance of contamination which often strikes larger units (1).

Types of Under Sink Water Heaters

In general, there are two types of under sink water heaters — tank-type and tankless type. Both have their pros and cons, but let’s take a zoomed-in look at both.

Tankless Water Heater

Product Image of the EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology

An under sink tankless water heater is the smallest heater you’ll come across. The average length is about the same as a laptop.

These heat the water without using a storage tank, meaning that you’ll get what you need. As soon as you open up the hot water tap, warm water will stream until you switch it off.

Because there’s no large tank included, these are super easy to fit under the sink or where you may need it. These are also the most cost-efficient, seeing that they don’t use much energy or water. Most also come with a turning dial or remote control to set the right temperature.

However, they’re not the best choice if your hot water demands are high, for instance, if you have a large family (2). Doing several demanding tasks at the same time can become too much for the tankless water heater.


  • Instant hot water — powerful GPM (gallons per minute).
  • Economical energy cost.
  • Small, compact size, easy to install.
  • Requires less maintenance.


  • They’re generally pricier than tank-type instant water heaters.
  • Not for people with higher water output.

Tank Water Heater

Product Image of the Bosch Electric Mini-Tank Water Heater Tronic 3000 T 4-Gallon (ES4) - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted

These are the affordable choice for many, seeing that they don’t cost as much and use less water. They usually come with a mini tank that can hold 2 to 2.5 gallons of water. Some may have larger tanks, ranging up to 7 gallons.

Similar to the tankless type, this one is also straightforward to install. Most allow you to mount them on the wall, under your sink, or directly onto the floor. However, you will need a bit more space for the mini tank.

These are a great choice if you own an RV, boat, or small apartment. Although it has a tank, there’s no need to install extra pipes around your house. Just install it where you need it.


  • Most affordable choice.
  • Works well even if you have a larger water output.
  • Provides an adequate amount of hot water for smaller uses such as washing hands and doing a few dishes.


How to Choose the Best Under Sink Water Heater

There are a couple of things to look for and consider before buying an under sink water heater. It all depends on your water usage and where you need it the most.


Water heater size is probably one of the most important factors to consider. The reason why many opt for these water heaters is that they have less space available.

Although not as much as your regular unit, water heaters with tanks take up more space than tankless. Take a good look at the area where you want the unit to be and decide accordingly.


Some instant electric water heaters have a high electricity demand. You need to be sure how much your power circuit at home can take.

How many volts the instant heater needs depends on the model. Some take around 120 volts, while others require 240 volts.

Hot Water Demand

Calculating approximately how much hot water you need per minute will help you make an informed decision.

All under sink heaters have a fixed flow per minute of hot water. It’s estimated that the average American uses around 2.1 gallons of water per minute for an 8.2-minute shower (3). Although for some it might be as little as 1 gallon or perhaps more than 2.5 gallons.

Your Location

The temperature of the incoming water differs between North and South, East and West. Temperatures are generally warmer further South, then they are up North. This means that if you live in Texas, for example, you don’t need a water heater as powerful as one living in Alaska.

It’s of course totally up to you, but making the right choice here could perhaps save you some money. Choosing a water heater that’s too powerful while your inlet water is already warm, could cause your electricity bill to rise. A stronger heater uses more energy.

You Might Also Like
Home tankless gas water heater5 Best Tankless Gas Water Heaters (2021 Reviews)

The Best Under Sink Water Heaters of 2022

Here are 5 excellent under sink water heaters to choose from.

1. Bosch Electric Mini-Tank Under Sink Water Heater

Best for Low Hot Water Demands

The Tronic 3000 T is a point-of-use mini-tank water heater with three sizes available, but we chose the 4-gallon tank. For those with lower hot water demand, this is the better choice—for example, a single sink far away from your other unit.

This under sink water heater is made with premium glass-lined material. It’s insulated with a layer of thick CFC-free foam, providing supreme energy efficiency.

Thanks to the compact size of this water heater, it fits perfectly under the sink. You can choose to simply mount it on the wall or a shelf using the included bracket. It has a sleek design that easily blends in with most decor.

It comes with a fitted thermostat where you can choose between “ideal,” “max,” and “min.”

The Pros

Perfect for the Smaller Uses

Thanks to the 4-gallon mini-tank, this water heater provides enough hot water for your everyday small uses. This could be that sink at the other end of your house.

Energy Efficient

On the inside, it’s lined with CFC-free foam. It’s a thick layer, which means that the water heater uses less energy. It uses minimum power, even on the highest setting.

Short Waiting Time

After you install it under your sink, it provides hot water in an instant. It takes under a minute to heat the water, and after you close the faucet, it stores the leftover hot water.

The Cons

Thermostat Is Too Simple

Some users pointed out that the thermostat is too simple. It’s difficult to figure out the exact temperature since the range is quite broad.

Can’t Place It Directly on the Floor

Although the manufacturer claims that you can easily mount it on the floor, the bottom is curved. This means that you’ll need a stabilizer underneath to keep it from moving.

Additional Specs

Tank volume 4 gallons
Voltage 120 V
Recovery rate 6.8 GPH
Temperature range 65 to 145 degrees Fahrenheit
Weight 17.4 pounds
Dimensions 13.75 inches by 13.75 inches by 13.5 inches

2. EcoSmart ECO 11 Tankless Under Sink Water Heater

Best for Energy Efficiency

The EcoSmart ECO 11 is great if you’re looking to take some of the load off your current water heating unit, and save energy. This tankless instant water heater from EcoSmart is just what any eco-conscious homeowner needs.

With this water heater, you’re likely to save money on your water and electricity usage by as much as 50 percent. EcoSmart claims that their tankless water heaters have a uniform energy factor of 0.98. This unit is a whopping 99.8 percent energy efficient.

EcoSmart’s range of tankless water heaters is designed with patented self-modulating technology. This allows each unit to regulate the energy output, ultimately ensuring optimal performance.

It’s conveniently compact, yet very sleek to look at. It has a thermostat and a digital screen displaying the exact temperature.

The Pros

Saves Loads of Energy

EcoSmart was really eco-smart while producing this water heater. It’s 99.8 percent energy efficient, producing only hot water according to need. It heats up instantly as you need it, and turns off when not in use.

Small, Convenient Size

It measures around 11.5 inches by 8 inches. It’s very lightweight, weighing only 6.5 pounds. You can mount it on nearly any wall, but it’s best close to the water source.

Digital Display and Thermostat

One of the greatest features is the digital display that clearly shows how hot the water becomes. The easy-to-use thermostat makes it even easier to operate. It’s smooth to turn, giving a bit of that smart-tech feel.

Included Lifetime Warranty

This isn’t really something that you’ll see with every product, so it’s a definite plus. However, the warranty is limited, in that it doesn’t cover any incidental damages.

The Cons

Not for Higher Hot Water Demands

EcoSmart designed this specific model for smaller uses. It works best if it’s close to the water outlet, such as a sink or shower. This means if you’re multiple people using hot water simultaneously, the water will run cold.

Won’t Perform as Well in Colder Regions

EcoSmart warns that the water heater works best if temperatures stay above 67 degrees Fahrenheit.

Additional Specs

Tank volume Tankless
Voltage 240 V
Recovery rate 2 GPM
Temperature range 80 to 140 degrees Fahrenheit
Weight 6.5 pounds
Dimensions 11.5 inches by 8 inches by 3.75 inches

3. Thermoflow UT10 2.6-Gallon Mini-Tank Under Sink Water Heater

Best for Colder Regions

Living in colder regions, under sink water heaters aren’t optimal. This model from Thermoflow, however, will surprise you.

What makes it great for colder regions is its frost protection mode. It will start as soon as the temperature drops too low. Still, avoid placing it where there’s a risk of freezing.

Its second mode is an energy-saving mode. The tank itself is made from stainless steel and lined with an EPS foaming heat system. The foam lining helps to heat up the water quicker, eliminating long waiting times while saving energy.

To save extra energy, this instant water heater has something called a “thermostop” function. This means that when the unit reaches the set temperature, it stops heating automatically until you need it again.

The Pros

Frost Protection Mode

Thanks to this helpful feature, even those living up North can benefit from using this heater. Normally, under sink water heaters will perform quite badly in colder weather. Fortunately, this one seems to be the answer — thanks, Germany!

Energy Efficiency

This heater works fast and efficiently without wasting excessive energy. This is mostly thanks to the EPS foaming heat system and the thermostop function.

Stainless-Steel Material

The tank is made from stainless steel, which means it’s quite resistant to rust and abrasion. Thermoflow even claims that it doesn’t require any maintenance.

The Cons

Installing May Take Some Plumbing Know-How

Quite a few users noted that it’s difficult to install. It seems to require different sized wires and pipes. These are available in the U.S., but you may have to consult a plumber.

Additional Specs

Tank volume 2.6 gallons
Voltage 120 V
Recovery rate 2.6 GPM
Temperature range 45 to 167 degrees Fahrenheit
Weight 14 pounds
Dimensions 18 inches by 12.2 inches by 11 inches

4. Camplux ME25 Electric Under Sink Water Heater

Best for Outdoor Living

Camplux provides a perfect example for those enjoying the great outdoors. This small under sink water heater fits perfectly in any RV, boat, or even the patio kitchen station.

The water heater has a 2.5 gallon, glass-lined water tank with extra insulation. This tank is all about efficiency, heating around 6.8 gallons per hour. It comes with an easy-to-use thermostat.

On the thermostat dial, look out for the little snowflake image. When the heater isn’t in use for longer periods, mostly in the winter, turn the dial to the snowflake. This is a freeze-protection setting preventing any remaining water from freezing.

Another great feature is overheating protection. This will give you that extra assurance that you and your family are safe.

The Pros

Easy-To-Use Thermostat

The thermostat is straightforward to use. Turn it to high, medium, or low, and let it work.

Freeze Protection

If you’re installing this unit in your RV or boat, this feature is essential. Not many people spend the winter in their RV or boat, so this will keep it protected.

Overheat Protection

With this under-sink water heater, you’ll also have some assurance that it won’t cause a fire. It has overheat protection which prevents the unit from overheating.

The Cons

Dimensions Stated Are a Bit Misleading

Some users pointed out that when you measure to see if this can fit in a cabinet, you have to add at least 4 inches. This is due to the pipes.

Additional Specs

Tank volume 2.5 gallons
Voltage 120 V
Recovery rate 6.8 GPH
Temperature range 77 to 140 degrees Fahrenheit
Weight 20 pounds
Dimensions 17.25 inches by 11.75 inches by 10.38 inches

5. Ariston GL6+S Electric Under Sink Water Heater

Best for High Hot Water Demands

Bosch is one of our all-time favorite brands, and this is one of their larger under sink water heaters. It provides enough hot water for a big family. This is perfect if you’re like me and the water always runs cold before mom gets to finish her shower.

This Ariston water heater consists of a 6+ gallon water tank. It’s quite large, measuring 14.5 inches by 17.5 inches and weighs approximately 30 pounds.

It’s also super easy to install. Simply place it under your sink, connect to the water pipes, and plug it into a standard outlet. Similar to our earlier example from Bosch, this Ariston also has a glass-lined tank.

The Pros

Works Perfectly for Higher Hot Water Consumption

This Ariston under sink water heater is perfect for those needing that extra hot water. It has a large 6-gallon mini-tank that will store the hot water until you need it.

Easy to Install

The installation is a relatively straightforward process. You don’t need any hard wiring, just connect it to the water source and plug it in.

Comes With a 6-Year Warranty

Along with the amazing under-sink water heater, you’ll also get a 6-year warranty.

The Cons

Takes a Little Longer to Heat Up

But a few users pointed out that its recovery time was a little longer than the average under sink water heater. This might be due to the larger water tank. It takes about 10 minutes to heat up.

Additional Specs

Tank volume 6+ gallons
Voltage 120 V
Recovery rate 6.8 GPH
Temperature range 65 to 145 degrees Fahrenheit
Weight 29.5 pounds
Dimensions 17.5 inches by 17.5 inches by 14.5 inches

Under Sink Water Heater Comparison Chart

Product Award Volume Voltage Recovery Rate Temp Range Weight Dimensions
Bosch Electric Mini-Tank Low Hot Water Demands 4 gal 120 V 6.8 GPH 65 – 145 F 17.4 lbs 13.75″ x 13.75″ x 13.5″
EcoSmart ECO Energy Efficiency N/A 240 V 2 GPH 80 – 140 F 6.5 lbs 11.5″ x 8″ x 3.75″
Thermoflow UT10 Colder Regions 2.6 gal 120 V 2.6 GPH 45 – 167 F 14 lbs 18″ x 12.2″ x 11″
Camplux ME25 Outdoor Living 2.5 gal 120 V 6.9 GPH 77 – 140 F 20 lbs 17.25″ x 11.75″ x 10.38″
Ariston GL6+S High Hot Water Demands 6+ gal 120 V 6.8 GPH 65 – 145 F 29.5 lbs 17.5″ x 17.5″ x 14.5″

Headshot of Peter Gray

About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.