8 Best Under Sink Water Heater Reviews [Buying Guide Inside]

Under sink water heaters provide instant hot water supply. They are trendy, compact in design, highly portable, and pack all the punch to fulfill your hot water requirements daily. Ideal for both residential and commercial purposes, they can store up to 7 gallons of water and are energy-efficient. 

This article reviews the best under sink water heaters you can buy in 2023. Our in-house experts have spent hours researching, analyzing, and testing to get you the best deal in the market. We understand that choosing a unit out of the massive variety can be a tough task, which is why we have toiled to help you buy the heater that’s worth its promise. So, take a look.

Under sink hot water heaters are designed specifically to meet your sink or hand-washing requirements. These are small electrical units that can be wall or floor mounted and supply hot water uninterruptedly. They are also known as POU or point-of-use water heaters, which mean they offer hot water instantly.

Under the sink water heaters are excellent to use in the kitchen, garage, patio, and other areas of a house where a large water heater cannot be installed. Or, they can be used when there is more demand of hot water or immediate requirement of hot water.

These water heaters are compact than big water heaters and hence more energy efficiency. They require less energy and heat up small volume of water at a time. Using these under counter hot water heaters let you save money on your energy consumption or utility bills.

The mini water heaters under sink are available in two variants – Tank and Tankless.

• Water Heaters with Tank

A tank with water heater means it can heat up a small volume of water and store the same for later use. Such models can hold between 2.5 – 7 gallons of water at one time. It is an excellent option for those who want hot water to store in their heater.

Also, it means that there is less wastage of hot water. Such models are very easy to install and can be plugged into the standard electrical outlet. It is best to pick these models when a faucet is located nearby.

• Tankless Water Heaters

The other type of water heater is a tankless water heater. They are meant for use when no storage of hot water is needed. It instantly heats water and passes the same through the system as long as the water is running.

This water heater is an excellent option to save energy in the house as it regularly works hard to maintain hot water supply.

The hot water supply is availed till the water is flowing. The under sink tankless water heater is compact and smaller and does not require much space for installation. However, they need slight more setup than the tank version.

It is important to pick the right water heater under the sink to ensure that your entire requirements are met completely. Here are a few important considerations to ensure you pick the best under sink water heater.

1. Size of Heater: It is first essential to select the right size of the heater. It must fit appropriately in your preferred space. Hence, make sure you check the heater’s dimensions before you buy it. Buying a too big heater will expose it while a too small unit may not be able to serve you to the fullest.

2. GPM or Flow Rate: The flow rate of a water heater is estimated in GPM or Gallons per Minute. The higher flow rate of a heater, the more easily it can heat the water. If your water heater’s GPM is 1 it can heat 1 gallon water per minute. Hence, if you need more hot water, you want to purchase a heater with a higher GPM. It is best to pick the water heater with decent flow rate at least.

3. Capacity: If you are picking a tankless water heater, it is not necessary to consider the tank’s size. But if you wish to pick a heater with tank, you must check its tank size. The tank size of a heater must be between 2.5 – 7 gallons to avail of uninterrupted supply of hot water. A water heater with bigger tank is best to meet your various needs.

4. Voltage: It is important to consider the voltage of electrical equipment, which requires powering the unit. It is essential to check that the electrical outlet you use can efficiently handle the water heater’s voltage. Most water heaters use 120V outlets, but there are others that may need a higher voltage supply.

5. Recovery Rate: The recovery rate of a heater refers to the number of gallons of water that unit can heat. The standard increases the temperature by 90 degrees Fahrenheit in one hour. This recovery rate is estimates in gallons per hour or GPH.If recovery rate of a heater increases to 6.8 GPH, it can heat 6.8 gallons of water to 90F in one hour. A higher recovery rate is essential for a water heater to offer quick supply of hot water.

6. Heating Power: The heating power refers to the power a unit uses for heating the water. Units with lesser heating power cannot heat bigger water quantities. The volume of KW a heater requires depend on how much water you want to heat and the demand for total gallons per minute.Water heaters with higher KW can heat more volume of water at a faster pace and offer a higher boost in temperature.

7. Energy Efficiency: High energy efficiency is essential for a water heater. A heater with higher energy efficiency ensures there is less wastage of energy and storing huge volume of water is easy. Hence, check the energy efficiency rating for the unit.A water heater offering energy efficiency of 96-98% is a best pick as they cut down a huge amount of energy and lets you save a lot of money.

8. Maintenance and Installation: Different kinds of water heaters involve different types of maintenance and installation. There are plug-in style models available, which are very easy to install. A few water heaters required additional hard wiring or plumbing and electrical work.It is best to hire an electrician or plumber for installing complex models. Make sure you go through all the maintenance requirements and instructions before purchasing the heater.

9. Safety: It is of utmost importance to check the safety features of a water heater. Units with advanced safety features are easier and safer to use. There are water heaters with thermostat that makes it convenient to regulate the water temperature.

10. Modulation: It is another safety feature to consider for a water heater. This feature ensures that a unit can alter the heat output against the flow rate of water through the unit. It also keeps the water temperature regulated even if the flow rate is varying.Water heaters with pressure relief valve prevent damage from happening because of excessive pressure of water. When the pressure is extremely high, the valve relieves pressure and makes it safer for use.

11. Price: Price is a major factor to consider when picking a water heater. Also, it is important to consider the use of water heater and the volume of water heater needed.

12. Warranty: The warranty of a water heater is another aspect to consider. There are some manufacturers that offer long-term warranty on exterior body while some offer warranty only on the internal components. It is best to pick a manufacturer that offers warranty on both internal and external components of a heater.

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1. EcoSmart Eco 11 Tankless Water Heater Electric

USP: Excellent Energy Efficiency

Based on the brilliant ECOSMART tankless heating technology and holding energy efficiency of up to 99.8%, the ECO 11 water heater ensures you never run out of hot water even when it is extremely hot. It comes with patented self-modulating technology allowing the units to have complete control over the energy output for delivering optimal water heating.

It is an excellent product for small apartments and can efficiently heat up to 2 gallons in one minute and is ideal for weather of 67 Degree Fahrenheit and above. It can handle two sinks simultaneously in colder regions. It is a compact design when installed properly can save money to a great extent.

It saves up to 50% heating costs. Also, the modern, sleek, and wall-mounted design takes very less space freeing up the floor space for storing things. It is integrated with numerous advanced features and uses only the needed volume of energy.

Specifications

Flow Rate – 2.6 GPM

Voltage – 220

Recovery Rate – 6.8 GPH

Weight – 6.5lbs

Size – 11.5 x 8 x 3.75 inches

Heating Power – 13KW

Pros

Space saving design

Excellent energy efficiency

Self-modulating technology

Tankless heating mechanism

Can supply hot water to two showers simultaneously

Heats up to 2-gallon water in one minute

Cons

May develop leak overtime

It does not stores water

2. Bosch Electric Water Heater Mini-Tank

USP: Instant Hot Water

Next, we have electric water heater by Bosch, which can heat up to 2.5 gallon using the point-of-use technology. It perfectly fits under the sink of all sizes and delivers hot water instantly. With a thermal efficiency of 98%, it is a compact design, which can be mounted on the floor and wall.

It is a great instant water heating source useful for one sink at a time. You can use it as sole source for water heating or buffer installed in-line with tankless water heaters experiencing intermittent cold water. With pressure and temperature relief valve, it supplies water where needed. The thick CFC-free foam insulation offers maximum energy efficiency while tank with glass lining enhances durability.

In addition to independent installation, it offers fast recovery rate, and hence, eliminates long waiting for hot water at the sink. It comes with brackets and can be easily mounted on the floor or wall. Once installed, you only have to switch on the hot water supply and you will get immediate hot water supply.

Specifications

Flow Rate – 2.5 GPM

Voltage – 120V

Recovery Rate – 6.8 GPH

Weight – 15.5 pounds

Size – 2.5 gallons

Heating Power – 1.44 KW

Pros

Long-lasting quality

Great recovery rate

Easily mounted

Instant hot water supply

Integrated with Bosch Thermo Technology

Point-of-Use mini tank heater

Cons

It anode may require frequent inspection.

Excessive use may lead to leaks at the bottom.

3. Stiebel Eltron 1300W 233219 Mini-Tank Water Heater

USP: Water and Electricity Saving

Designed in Germany, the Stiebel Eltron mini-tank water heater is an electricity and water saving design that supplies hot water right where you need it for convenient, fast, and energy-efficient use. It comes in an attractive and sleek design perfectly complementing modern décor. It can be used as a stand-alone unit or bugger tank for running hot water supply while minimizing delays.

Available with a standard 120 volt outlet, it offers convenient installation. The pipe runs are reduced along with the use of energy and water. The compact tank comes with world-class insulation. The lowest stand-by loss saves money and reduces energy requirements. The best thing is that this product is engineered using all high-quality products.

It comes with a unique flat back design allowing convenient mounting on the wall. There is a simple thermostat dial located on the top allowing easy temperature adjustment. Also, it comes with a unique frost protection setting, which is perfect to maintain internal tank temperature above freezing. The tank delivers hot water instantly and ensures you gain complete comfort while using it.

Specifications

Flow Rate – 2.5 GPM

Voltage – 120V

Recovery Rate – 6.8 GPH

Weight – 15.9 pounds

Size – 18.7 x 11 x 10.7 inches

Heating Power – 1.3 KW

Pros

Convenient temperature adjustment

Flat back offers easy installation

Get immediate hot water

Saves electricity and water to great extent

Can be used as buffer tank and standalone unit

Ideal for point-of-use applications

Cons

Recovery rate reduces with increase in volume of water

Slightly heavy design

4. Camplux ME25 2.5 Gallon Mini Tank Water Heater

USP: Efficient Outdoor Unit

Belonging to the famous JAL group, Camplux electric water heater is an efficient outdoor unit offering long-lasting functionality. Based on the point-of-use technology, its mini water tank stores up to 2.5 Gallons of water and supplies hot water under basin or sink when you need. It is an ideal unit for patio, basement, kitchen station, garage, attic, and other places.

This water heater is not only easy to install, but it eliminates the hot water wastage by reducing heat loss. It comes with glass-lined water tank offering absolute durability and great insulation along with quick recovery rate eliminating long waits for the hot water. The external dial design offers complete control over temperature range, while the pressure and temperature relief valve enhances safety.

This is a stylish design that blends perfectly in your home décor. It is equipped with adjustable thermostat that automatically sets the water temperature control. Also, it comes with a thermostat knob for extended protection to guard water against freezing. The high efficient heating element involves low maintenance and saves your energy bills to a great extent.

Specifications

Flow Rate – 2.5 GPM

Voltage – 120V

Recovery Rate – 6.8 GPH

Weight – 17.16 pounds

Size – 11.75 x 17.25 x 10.38 inches

Heating Power – 1.4 KW

Pros

Easy to install plug-in style

Available in both wall mount and floor mount design

Quick recovery rate

Advanced thermostat function

Freeze protection technology

Temperature control mechanism

Cons

It requires professional assistance for installation.

It offers hot water supply only for one shower at a time.

5. Ariston Mini-Tank GL4S Electric Water Heater

USP: Super Convenient Installation

The Ariston point-of-use electric water heater comes with a mini-tank and is one of the best under sink water heaters. It eliminates the hot water wait time to a great extent and heats 4 gallons of water in very less time. The heater can be installed independently or in-line with a bigger water heating source.

It requires no hard wiring to power the unit and can be plugged into any standard outlet. Its glass-lined tank offers long service life while superior insulation offers fast recovery and better energy efficiency. With a weight of 17 pounds, it is an aesthetically pleasing design that will perfectly fit into your contemporary décor.

The heater is backed with long-term warranty and can be positioned right where you require it. Offering superior insulation, it provides greater efficiency and can even be installed independently with a bigger water-heating source. Go for this water heater if you want instant supply of hot water for your sink’s faucet.

Specifications

Flow Rate – 2 GPM

Voltage – 120V

Recovery Rate – 6.8 GPH

Weight – 23 pounds

Size – 13.8 x 13.5 x 13.8 inches

Heating Power – 1.5KW

Pros

Point-of-use water heating technology

Offers instant hot water supply

Can be installed with a bigger water-heating source or independently

Backed with long-term warranty

Big size 4 gallon water tank

Requires no extra hardwiring

Cons

Slightly expensive than its counterparts

The wait time for hot water may be quite long

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6. ATMOR AT-900-03 0.5 GPM Sink Aerator

With the Atmor water heater, you can easily save money, water, and energy. It is a convenient and efficient water heating solution based on the point-of-use functionality offering unlimited supply of hot water without ever running out. It is specifically designed for single sinks in regions with a minimum of 57 Degree Fahrenheit water temperature. It is a compact design that can be installed on the wall or floor. However, it needs a 30 Amp dedicated single-phase breaker.

It is a full-capacity design integrated with the Atmor patented canister technology holding an exclusive mechanism for identifying water pressure and flow. The plastic based canister composes of plastic and glass fiber, which is safe to use against electric shock. The canister offers better insulation for convection and higher energy efficiency. It offers a maximum flow rate of .5 GPM, which reduces at higher temperature.

It offers endless and instant hot water supply on demand without worrying about water running out. With a 0.5 GPM Aerator for pressure relief device and sink faucet, it ensures that you optimally meet your hot water supply requirements.

Specifications

Flow Rate – 0.5 GPM

Voltage – 110V

Recovery Rate – 6.8 GPH

Weight – 4.19 pounds

Size – 11.95 x 8.7 x 4.2 inches

Heating Power – 3KW

Pros

Let you save water to a great extent

Compact unit can be installed on the floor or against wall

Comes with advanced sink aerator

Excellent unit for hand washing sinks

Endless and instant hot water supply

Ideal for commercial and residential use

Cons

It is not a plug-in style and requires 30 Amp single-phase breaker

The flow rate may reduce when more water is heated

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7. Ecotemp EM2.5 Mini Tank Water Heater

The Ecotemp 2.5 is a point-of-use water heater with a 2.5 gallons tank capacity. It is designed to offer on-demand hot water to a faucet and is a compact, lightweight, and small design allowing ideal use for commercial, residential, and commercial applications. It supplies hot water up to two sinks and can be installed with the existing hot water system ensuring immediate hot water whenever required.

The water heater is incorporated with accessible and easy temperature controls offering a minimum recovery time of 20 minutes. It is engineered to function at a water pressure of 150 psi. Convenient installation allows the unit to be mounted free-standing or on wall. It offers instant hot water on places that are difficult to reach and can be installed under the sink in your laundry room, kitchen, office, or utility sink.

It is an ETL certified product that holds 20 minute recovery time. The adjustable temperature ranges from 50F – 140F. It comes with pressure and temperature relief valve and mounting bracket. The sleek and compact design ensures that you can gain endless supply of hot water with ease.

Specifications

Flow Rate – 2.5 GPM

Voltage – 120V

Recovery Rate – 6 GPH

Weight – 20 pounds

Size – 14.75 x 13.25 x 11 inches

Heating Power – 1440 Watts

Pros

Compact design fits anywhere

Ready to install

Adjustable temperature control up to 140 degree

Wall and floor mountable design

45 minutes recovery time

Requires no expensive re-circulating pumps and lines

Cons

The fittings are plastic made.

The unit will not work up to mark during extreme winters.

8. Thermoflow Electric Mini-Tank UT10 Water Heater

USP: Minimal Standby Loss

The Thermoflow UT10 mini-tank water heater works on point-of-use technology thereby optimally meeting your instant hot water supply needs. Whether you use it as a buffer tank, standalone unit, or a supplement, it reduces standby loss to a great extent. It comes with auto cut-off protection feature that cut off electricity when the water overheats than the set temperature. As a result, the damage to the heater is also reduced to a great extent.

It comes with a stainless steel tank, which is highly durable and easy to maintain. It is highly energy-efficient thereby saving energy, water, and your utility bills. The plug-in style makes it extremely easy to install. You can install it in the basement wet bar, garage, patio kitchen station, attic, boat, or an RV to gain hot water immediately. It perfectly fits under the sink and supply hot water in just a few seconds.

The short distance ensures your hot water wait is reduced to great extent. It is a premium product that reduces standby water loss. With 2.6 gallons capacity, it provides hot water whenever and wherever you require. The fast recovery rate alleviates long waits for hot water and can serve 2 sinks at a time. It is a lightweight and compact design perfect for small spaces.

Specifications

Flow Rate – 2.6 GPM

Voltage – 120V

Recovery Rate – 6.8 GPH

Weight – 1.8lbs

Size – 18 x 12.2 x 11 inches

Heating Power – 1.5 KW

Pros

Low Standby Loss Power Consumption

Quick supply of hot water

Blend seamlessly with small spaces

Plug-in style, easy to install and use

Maintenance free high-quality stainless steel tank

Auto cut-off for safety

Cons

It comes only with floor mounting option.

The temperature control knob looks slightly odd.