4 Best Under Sink Tankless Water Heater Reviews & Guides

The under sink tankless water heater is a device that is designed mainly for installing under your sink. You can get this water heater for kitchen or bathroom sink. You can also mount this unit anywhere on the wall of your house. These units provide a very low water flow rate, which means these can only supply hot water to just one bathroom at a time. There are a few models that can support just one faucet. 

These units are also called under counter tankless water heater. You can widely use such under sink water heater for dishwasher or washing machine. The climate or weather hardly influences the water flow rate of such a point of use water heater. Most of the units designed for kitchen are electric Tankless Water Heater types. It is very easy to install them mainly because you don’t need to install any venting before that. The battery-operated design makes it easy to utilize.

We have compiled a list of different models for really helping you out in getting the best instant water heater for kitchen or bathroom. Please check it out to make a final decision on which one should you get.

Top 4 Best Under Sink Tankless Water Heaters

Atmor 27kW240VAtmor 27kW/240V4.5
Bosch Tronic 2.5-GallonBosch Tronic 2.5-Gallon4.6
Ecosmart POU 3.5 Point of UseEcosmart POU 3.5 Point of Use4.3
PrecisionTemp RV-550PrecisionTemp RV-5504.5

Top Reviews About Under Sink Tankless Water Heaters:

The following are a few of the models that you can really consider getting. Keep on reading for knowing more about them and make a final decision. 

1. Atmor 27kW/240V Electric Tankless Water Heater:

You can directly install this water heater under kitchen counter or the wall of your bathroom. This tankless water heater provides the temp range between ninety 90-135 degrees Fahrenheit. This unit is very small and can save a lot of space. For setting the temp, it comes with a digital temperature control system. With the help of this system, you can really adjust the suitable temp in hand washing or bathing. 

The ThermoPro self-modulating mechanism will automatically regulate the energy needed for heating up the water, and it can heat up the water just when you require hot water. This under sink tankless water heater can detect water flow automatically. For lowering the water consumption and eradicating the wasted water flow, this device automatically switches on/off. 

However, you will have to fit a pressure relief device, and you will have to purchase it only from the manufacturer. As for the internal material, the durable stainless steel, which also has corrosion resistance, can also prolong this unit’s life expectancy.

under sink tankless water heater
under sink tankless water heater


  • Digital temp control
  • Light-weighted, just seventeen pounds
  • Self-adjusting system 
  • Energy efficient
  • Small footprint
  • Detects water flow automatically


  • Have to fit a pressure relief

2. Bosch Tronic Electric 2.5 GPM Mini-Tank Water Heater:

This tank water heater can only store a small amount of water in its small tank. It has a small and compact shape, which makes it easy for you to install it anywhere in your house. You should rally install in under your sink for having the fast heating time. This Bosch under sink water heater provides with 2.5 GPM of water flow rate. This model is suitable just for a sink, not for bathing. You can put it on the floor or mount it on your wall. Installing this device is straightforward and very easy. 

Operating this unit is also very easy. You just have to plug it into an outlet, and it will start working immediately. You will not have to sue any complicated machinery for making it work. However, the only problem with this model is that it lacks consistency in the temp of the water. Whenever you turn off the tap, you have to wait another few secs to heat the water up.

best undercounter tankless water heaters
best undercounter tankless water heaters


  • Simple to be installed
  • Compact design
  • GPM water flow rate
  • Short waiting time for the heated water
  • Low price


  • It is not right for the large home use.
  • Lack of consistency on the water temp

3. Ecosmart POU 3.5 Electric Point of Use Tankless Water Heater:

This model is one of the best point of use tankless water heaters that are available in the market. You can directly install this unit under your kitchen or bathroom sink for faucet use only. It provides with max 0.5 GPM of water flow rate. This water flow rate is very low, but still, it can fulfill the hot water demand of faucets. Even though it has a small shape, it still comes with other amazing features such as the advanced flow control. 

According to the flow rate change, the water temp will automatically adjust. It can really save up sixty percent on the water heating bills for long-term usage. It is the smallest unit in the Ecosmart tankless devices and can provide hot water to only one faucet at a time.

The lowest inlet water temp is fifty-seven degrees Fahrenheit, which means it will activate just when the inlet water temp is above fifty-seven degrees Fahrenheit. Because of the lightweight design and small shape of this device, it can be perfectly utilized for offices, boats, and recreational vehicles (RVs).

best undercounter tankless water heater reviews
best undercounter tankless water heater


  • High energy efficient
  • Can save up to sixty percent on the water heating charges
  • Flow control system
  • Perfect for the under-sink use
  • Compact shape


  • The waiting time for is quite long

4. PrecisionTemp RV-550 Tankless Water Heater:

It is another type of tankless water heater for instant hot water at the sink. You may not just use this model for your tiny house, but it can also be used for the mobile washing services, trailers, and RVs. It uses propane as the main source of energy. You will just need twenty pounds of propane for making it work, and you can have ninety gallons of heated water. 

For the warmer regions or normal conditions, this tankless device just needs approximately 1.5 AMP. But in the winter season, you might require three AMPs for activating it. Its weight is about thirty-two pounds. This tankless unit can take up the half-space size and can weigh 1/3 as much as the ten-gallon tank.

best tankless water heater for sink
best tankless water heater for sink

This machine’s per hour hot water output is 55000 BTU. The free protection system permits the burner to fire, and all its electrical elements are then activated once it senses the wintry weather so as for taking the action on protecting the device.


  • Free protection system
  • Wide range of applications
  • Automatic gas modulation
  • Space saver
  • Energy efficient


  • The waiting time is a little long, takes about one minute

Under Sink Tankless Water Heater Features:

The following are some of the features that the tankless water heater designed specifically designed for under sink installation comes with:

Under Sink Tankless Water Heater Features
  • Faucet Use Only:

The power of this machine is quite small, as it is a low flow rate tankless water heater. Also, this tankless unit isn’t capable of supporting full bathroom use. If you want to utilize this system for bathing, you have to get a tankless water heating unit for a shower or simply order a whole-house unit. The max water flow rate of the under sink tankless water heating device is just 2.5 gallons per minute, which denotes you can utilize it for the faucet use only.

  • Simple Installation:

These under sink tankless water heating systems are usually the electric types. There is no complicated machinery added. And the installation procedure is quite straightforward and easy. You can totally fit it by yourself, and it takes just a little time.

  • Small And Compact Size:

The tankless water heater is usually designed compact and small, you can fit it practically anywhere that’s convenient, but surely the most commonplace is to for it under the sink. Thus this device can save much space in the house, particularly for the small or tiny studios.

  • Constant Supply:

For the under sink tankless water heating system for the kitchen use, you have to switch on/off the tap frequently in the washing dishes, or while doing laundries, therefore, it’s capable adequate for providing the constant heated water and can heat up the water instantaneously for meeting the urgent hot water requirements.

  • Fast Heating Time:

As this device is fitted right near or under the application fixture, the distance between the tap and heater is short; thus, the heated water flows fast to the destination spots.

Frequently Asked Questions Section:

  • Are Tankless Water Heaters Good For Restaurants?

Restaurants require a great sum of heated water and have got to heat water in a sec for meeting the urgent and busy requirements, you can get numerous under sink tankless water heating machines for the restaurants use only, but the charges are obviously not a small deal.

  •  Can The Under Sink Tankless Water Heater Be Used For Bathing?

A few of the large water flow rate and large power under sink tankless water heating units can be utilized as the bathing heater. But a few of these are quite low in power. If you want to use it for a bath, it can’t provide you with enough heated water. Therefore, if you desire a tankless water heating system for the shower, you can go for the large flow rate one.

Atmor 27kW/240V Tankless Water Heater is the best under sink type.

Atmor 27kW240V

Bosch Tronic 2.5 GPM Mini-Tank Water Heater is the best point of use one.

Bosch Tronic 2.5-Gallon

PrecisionTemp RV-550 Tankless Water Heater is the best unit for the RV use.

PrecisionTemp RV-550


All the products mentioned above can be regarded as the best under sink tankless water heater for the washing machine, for the kitchen, and also for your sink. They are created pretty small and compact, and that is the reason why they are suitable for tiny studio use. For summing it all up, we have picked three best ones according to diverse requirements for the sake of ease for you:

There’re also a lot of types of under sink tankless water heating systems available in the market, for having one in the most trustworthy way, Amazon can be the best option. You can also get a discount as there are constant discounts available on different products all the time. If you are interested in getting the item, then feel free to check out Amazon.