Best Under Sink Water Heaters of 2021 – Ultimate Review

| Last Updated: June 29, 2021

Having access to hot water at any time of day sounds great, doesn’t it?

While instant hot water might seem like a dream, it is now a possibility with an under sink water heater. These heaters are portable and very easy to use.

They provide you maximum comfort and relaxation. Let’s have a look at some of them along with their features, pros, and cons so you can choose one that meets your needs. 

Comparison Chart of the Best Under Sink Water Heaters

IMAGEPRODUCT
  • Made of high-quality materials to be long-lasting
  • Unit size of this heater is 4 gallons
  • 36” to 37” long card and 98% thermal efficiency
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  • Has a capacity of 60 cups per hour
  • Features a therma fuse (self-resetting)
  • Contains a stainless tank made of steel
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  • Best for the money
  • Contains EPS foaming technology and the latest Thermostop facility
  • Active safety circuit for protection
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  • Best under sink tankless heater
  • Has self-modulating technology and a 0.98 energy factor
  • Comes with a warranty for a lifetime
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  • Best under sink electric heater
  • Adjusts the power according to the water flow and temperature
  • Touch system for temperature control
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  • Best under sink on-demand water heater
  • Works on the latest German flow control technology
  • Has a 7-year warranty for leakage issues and a 3-year warranty for parts and purchases
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  • Best small under sink water heater
  • Energy efficiency of this heater is 99.8%
  • Can plug into an outlet of 110 Volts
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What is an Under Sink Water Heater?

Under sink water heaters are small and compact heaters, as the name suggests. You can fit them under your sink to heat the water within a few seconds. They are also known as point-of-use heaters. They provide hot water to the faucets directly.

You can heat the water in two ways, either by connecting the main pipeline to them or by using a storage tank heater. For tankless heaters, you need to connect them with the main cold water pipeline. They heat the water when the user sets the temperature. When they open the tap, hot water will pour in. For storage tank heaters, you need to fill water in their tanks. They heat it, and the user can use it whenever they want. These heaters are very helpful for instant heating.

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How Does an Under Sink Water Heater Work?

These heaters are very easy to use. You can install them without any difficulty by using the instruction manual. Users need to install them beneath their sinks (kitchen, washroom, and garages). They heat the water of the main supply, which is connected to it. Afterward, they supply this hot water to the faucets.

Using these heaters, you don’t need to wait for a long time. They consume less power and energy. These heaters need an outlet so that you can connect the plug for operating the heater.

Why Did These Models Make Our List?

If you buy these water heaters, then they will provide you with a lot of advantages. They contain the latest technologies and innovative features that make them worth buying. Some of the excellent qualities are:

Instant Heating

These under sink water heaters are a great replacement to the manual heating methods. You just need to install them under your sinks and near a power outlet. There is no need to use long recirculating pipes or tanks. They have a connection with the main hot water source. They heat the water within a few minutes using electricity.  

Less Space

Bosch Electric Mini-Tank Water Heater

These heaters consume less space because they are very small and low in weight. You can carry them anywhere. Under sink water heaters have a compact and simple design. They have attractive features like the latest thermostat and architecture. Thus, you can fit them under your sinks without worrying about the looks or compatibility.

Energy Efficient

You must be thinking that these heaters will consume a lot of energy and will increase your electricity bill drastically. But let us tell you that this is not the case. They are almost 50 percent energy-efficient.

They save your electricity bill because they operate only when you need hot water. They automatically turn off when the water is hot enough.

Review of the Best Under Sink Water Heaters

Are you searching for an under sink heater?

You don’t need to worry at all. We are here to sort out your problem. We have listed the best under sink water heaters so that you can select one for yourself.

Best Overall

Bosch Electric Mini-Tank Water Heater

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

Specifications

Max Water Flow (GPM): N/A

Energy Factor (EF): 98%

Dimensions: 13.75 W x 13.75 H x 13.5 D Inches

Water Temp Range: 65-145 Degrees F

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What Recent Buyers Report

According to recent buyers, this mini-tank water heater is great. It has excellent insulation and durability. It provides instant hot water for showering and washing. You can install and use it without any difficulty. It prevents water wastage and provides hot water for two sinks, at least.

Why it Stands Out to Us

This mini-tank water heater stands out to us because of its beautiful Italian design. It is 98% thermally efficient and very light in weight. It can work with many types of hardware. You can fit it on walls, floors, and sinks by using the brackets. Moreover, its glass lining provides a longer life expectancy.

Who Will Use This Most

Since this heater is portable, you can take it for RVing and picnic. You can fit it under your sink to heat the water. You can also use it for bathing, washing the dishes, and cooking. This heater provides enough water for 2 rooms. Thus, you can use it for two purposes at a single time.

Bottom Line

If you don’t want to wait long for hot water, then you must install this heater to heat the water quickly. You can use it for different purposes. It is very small, which makes it easy to carry. It has a temperature control system and a long power cord as well.

Pros

It is durable, compact, and small in size

Includes a bracket thus you can mount it anywhere like floor, wall, shelf, and sink

Very easy to use and maintain with glass lining material for increasing the lifespan

You can install it near a voltage outlet or in the line along with a source of hot water

No need to wait for hot water anymore, it can supply water to 2 sinks at a single time

Cons

There is an excessive build-up of calcium in the heater

You should include a ground circuit to avoid any electric shock

Starts leaking from below (valve of pressure relief) or inside after a few months

Runner-up

Waste King AH – 1300-C

Waste King AH-1300-C Quick and Hot Instant Hot Water Tank

Specifications

Max Water Flow (GPM): N/A

Energy Factor (EF): N/A

Dimensions: 8.1 x 6.8 x 11.2 inches

Water Temp Range: N/A

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What Recent Buyers Report

Customers have written in their reviews that they love taking showers using this heater. It provides hot water within a few minutes. It is a great replacement for the older versions of the heater. Despite its tendency to overheat, users are in awe of its features. It is much easier to install this heater than the previous unit.

Why it Stands Out to Us

This heater is present on our list because of its amazing specifications. It can heat 60 cups of water in one hour. You can also replace the heater if some faults or defects occur in it. Moreover, it has a fingertip thermostat through which you can set the temperature according to your needs.

Who Will Use This Most

People can use this heater to heat the water within a few seconds. You can also connect this heater with your hot tap. Users can use hot water for bathing, cooking, making tea, and coffee. People can install it in their cafes and restaurants as well.

Bottom Line

Summing it up, this mini tank heater is a perfect choice for heating the water quickly. It can provide you 60 cups of hot water per hour. It contains the latest thermostat technology. You can set the temperature using your finger. These heaters are worth buying to prevent corrosion.

Pros

Has a 1-year policy for replacement

Includes a compatible faucet and stainless tank

Can produce 60 cups of instant hot water per hour

Simple fingertip knob for adjusting the temperature

Comes with a lot of safety precautions for setting the temperature

Cons

Tends to overheat

Due to leakage, it can destroy your cabinet

To install it, you need extra space for the tap on the sink and an outlet in the cabinet below

Best for the Money

Thermoflow UT10

Thermoflow UT10 2.5 Gallons 110~120V Corded Electric Mini Tank Water Heater for Under Sinks 110V ~ 120V, 1.5kW Point of Use

Specifications

Max Water Flow (GPM): N/A

Energy Factor (EF): N/A

Dimensions: 18H x 12.2W x 11D inches

Water Temp Range: 45-167 Degrees F

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What Recent Buyers Report

You can use and install this heater without any difficulty as per the user reviews. Customers are very happy with their results. They like the precautionary measures and the latest technologies that are present in this heater. The temperature control knob is quite impressive. It has a great size and shape. People are satisfied with this heater.

Why it Stands Out to Us

This mini-tank heater is outstanding because it contains all of the features that are necessary for a water heater. It is affordable for everyone. This heater has the latest technologies and features. It can work on two modes, which means you can use it in every type of season.

Who Will Use This Most

This water heater is user-friendly. You can use it in your wet bars in the basement. People can carry it by themselves for RVing and boating. Anyone can use this heater in their offices to get hot water whenever they need it. You can also use them in your garages and kitchens.

Bottom Line

In a nutshell, this mini heater is perfect for many applications. It is not a burden on your pocket. It is equipped with excellent features. In other words, this heater is a must-have product for chilly areas. It is worth buying. It has amazing safety measures that will protect you from mishaps.

Pros

Two modes: energy saving and frost protection

EPS foaming technology provides faster and instant heating of water

Safety circuit that will turn off the heater whenever the water isn’t getting hot to prevent short circuits

Element and tank are made up of stainless steel, which provides durability, efficiency, and consistency

Thermostop function helps in using less power as it turns the heater off automatically when the water is hot enough

Cons

Not suitable for taking showers

Not compatible with small sinks

Pressure relief valves cause problems

Best Under Sink Tankless Water Heater

EcoSmart ECO 11

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

Specifications

Max Water Flow (GPM): 3.1

Energy Factor (EF): 0.98

Dimensions: 3.8 x 8 x 11.5

Water Temp Range: N/A

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What Recent Buyers Report

According to some recent reviewers, it is a perfect heater up till now. It consumes very little energy and fitting space. It is an affordable and easy-to-fix electric tankless heater. It gives endless warm water to the users. The performance and features of this heater are quite impressive.

Why it Stands Out to Us

This heater provides you endless warm water. You can use it for many applications. It is the perfect replacement for the storage tank heaters. It also comes with a lifetime guarantee. You don’t need to worry about the maintenance cost. Plus, it requires less power, time, and space to provide hot water.

Who Will Use This Most

People can fix this heater under their kitchen and bathroom sinks for washing and cleaning. They can also use it to wash their vehicles, pets, and gardens. People can use it in their laundry and salons also. In salons, they can use it for hair treatments, pedicures, and manicures.

Bottom Line

Wrapping it up, this tankless heater is an ideal choice for your regular use. It consumes less space, time, and energy than storage tank heaters. They are compact and lower in weight. You can use it for various purposes. Go and grab one for yourself.

Pros

Uses less energy and can provide hot water for two rooms

Requires very less space for installations due to its small size

Saves 60 percent of the heating cost for water from the utility bills

Since the heater has a lifetime warranty, you don’t need to worry about the repair or maintenance cost

Self-modulating feature provides only a specific amount of energy that is necessary for heating the water

Cons

You need to clean the elements after every four months

It works using electricity, which means no electricity so no hot water

Best Under Sink Electric Water Heater

ECOTOUCH Electric Tankless Water Heater

Tankless Water Heater Electric 5.5kw 240V, ECOTOUCH Point-of-Use Hot Water Heater Digital Display,Electric Instant Hot Water Heater with Self-modulating,Overheating Protection,White

Specifications

Max Water Flow (GPM): 1.2

Energy Factor (EF): 98%

Dimensions: 11″ x 7.5″ x 2.35″

Water Temp Range: 67-109 Degrees F

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What Recent Buyers Report

Customers have mentioned in their reviews that this heater deserves a lot of appreciation. It will never disappoint you with its result. It also comes backed by customer service. The quality of this heater is worth praising. It is very easy to install. It is a good solution for laundry and dishwashers.

Why it Stands Out to Us

This electric tankless heater stands out to us because it provides maximum safety to the customers. It has a sleek design, which makes it easy for you to install the heater near any outlet. It has the latest technology for temperature control. The power adjustment feature is quite impressive.

Who Will Use This Most

This heater is useful for small residential areas and factories. Industries that use hot water in their product-making process can use it too. It will save their utility bills and time. People can use it to heat up the water within a few minutes.

Bottom Line

In a nutshell, this is the best electric under sink heater available on the market. It provides you with hot water instantly, along with 100 percent safety. It will also keep your bill to the minimum. You can use it without any stress. Overall, it is perfect in terms of quality and performance.

Pros

Separate lines for electricity and water that prevent leakage or any sort of harm

Remote control system through which you can manage the installation process

Compact and sleek design, making it easier for you to install it anywhere closer to the outlet

Smart and intelligent temperature control mechanism and you can easily adjust the temperature

Smart self-power adjusting facility where input power depends upon the temperature and water flow, thus less wastage of energy

Cons

Mounting is not strong enough

Pressure of hot water is not good

Does not provide continuous water if the flow rate is above 2.5 GPM

Best Under Sink On Demand Water Heater

Stiebel Eltron Tankless Water Heater

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White, 20.2

Specifications

Max Water Flow (GPM): N/A

Energy Factor (EF): N/A

Dimensions: 4.63 x 16.63 x 14.5 inches

Water Temp Range: 68-140 Degrees F

$527.02 On Amazon

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What Recent Buyers Report

Customers are in love with this unit. This is because it provides hot water continuously without any hindrance. The reviews state that everyone must buy this heater for taking a soothing hot shower. They report using this heater in their homes and have no complaints about it.

Why it Stands Out to Us

This under sink heater stands out to us because of its high demand on the market. People love to use it in their homes. It utilizes very little power and provides hot water depending upon your settings. You can use it for various purposes. Every single penny that you will spend on it is worth it.

Who Will Use This Most

You can use this amazing heater for commercial and residential purposes. You can also fit it in your garage for washing out the car. Chefs can also use it to wash the greasy and dirty dishes without any difficulty. People who don’t have any access to gas can buy and use this product in their homes for cleaning, washing, and laundry uses.

Bottom Line

Summing it up, this heater is a perfect house tool. You can use it to do multiple tasks. It saves both energy and money. It won’t produce any sort of noise or vibration. The heater operates on advanced technology. After buying this, there won’t be any need to heat the water manually.

Pros

Does not produce any noise during usage

Digital display and preset memory button for temperature

No need for any venting or large space for storing hot water

Reduces the flow if demand is higher than the holding capacity

Latest German technology helps in controlling the flow of hot water

Small heater that consumes very little energy because of the auto modulation technique

Cons

It can cause fire and sparks

Does not provide enough warm water

Best Small Under Sink Water Heater

Ecosmart ECO MINI 2.5 2.5-Gallon Tank Water Heater

Ecosmart ECO MINI 2.5 2.5-Gallon 120V Electric Mini Tank Water Heater

Specifications

Max Water Flow (GPM): N/A

Energy Factor (EF): 99.8

Dimensions: 16.2 x 11 x 11 inches

Water Temp Range: N/A

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What Recent Buyers Report

According to some recent reviews, it is a great heater so far. It uses less energy and space. It is inexpensive and easy to install. They term it as an electric heater that provides endless hot water to people. The performance and specifications of this heater are very impressive and have been loved by all.

Why it Stands Out to Us

This heater provides you endless hot water. You can use it for many purposes. It is an excellent replacement for storage tank heaters. It consumes less power and space and comes with a lifetime guarantee. You don’t need to worry about the repair expense as well.

Who Will Use This Most

People can install this heater under their kitchen and washroom sinks for washing and rinsing. They can also use it for their cars and pets. Moreover, it can be used in cold areas for taking steam and hot baths. People can install it for washing clothes as well.

Bottom Line

Wrapping it up, this tankless heater is perfect for your daily use. It consumes less energy and power than storage tank heaters. It is small and has very little weight. You can install it under small sinks as well. What more can we ask for from an electric heater?

Pros

Lightweight and has lower energy consumption

No need to install long and expensive recirculating lines

In summer, it can heat the water for two sinks simultaneously

Eliminates the need for waiting and manually heating the water

Consumes little space as there is no requirement of pump or storage tank

Cons

Power buttons stop working after some time

Nearly impossible to mount it on a normal host

You cannot install it without any professional help

Advantages and Disadvantages of Under The Sink Water Heaters

Everything has some pros and cons. Similarly, under sink water heaters have some advantages and disadvantages. It’s essential to know of these before making a purchase. 

Advantages

These heaters are very helpful in many ways. Let’s have a look at some of its advantages.

Pocket-Friendly

These heaters are budget-friendly. They provide excellent performance at an affordable rate. It uses less energy; thus, it will also decrease the heating cost in your utility bills. They are energy efficient and save up to 50% of your energy consumption. Those under sink heaters eliminate the need for recirculating pipes and pumps. So it will save the installation cost too.

Avoids Wastage of Water

These under-sink heaters prevent wastage of water. They heat the ongoing water through the pipe. They do not require any extra storage tank. You just need to connect the ongoing water pipelines to the heater (main hot water source).

Desirable Heating

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How to Install an Under The Sink Water Heater

Installing an under sink water heater is not difficult at all. You need to follow these steps to install the heater and get hot water as soon as possible. These are the basic steps that need your consideration for installing a heater.

1. First of all, unbox the heater and take out all the accessories and equipment.

2. Now you need to think and prepare the place where you will fit this heater. You need to make sure that this place has a gas connection or a power outlet. Clean that place and make enough space for the heater. Go through the instruction manual to understand the connections of hoses.

3. Take out the compression vessel and pressure valve. Place everything at their respective places. Make sure that the pipes are straight before inserting the clips.

4. Now connect one end of the hose to the cold water supply and other to the faucet. Do consider the connections shown in the manual. Connect them according to the instructions given.

5. Connect the hot water source to the heater and mount the heater on the wall or floor. Plug it into the electric supply or connect it with the gas supply.

6. Don’t forget to connect all the breakers and safety measures. Then set the temperature according to your needs. Turn on the heater, and it will heat the water quickly.

Conclusion

Under sink water heaters is a perfect tool for those who need hot water quickly. People can use it for washing, cleaning, showering, and many more purposes. These heaters provide hot water within a few minutes. They are affordable and energy-efficient. For ease, you can select one heater from the top ones we have reviewed above. Any of these will surely make a great investment.



My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.