Best Under Sink Tankless Water Heater Reviews 2021 – Buyers Guide

Trust me when I say there is nothing as cool as getting an endless supply of constant warm water from the kitchen or bathroom faucet all day. An under sink water heater will most times encourage the kids to do the dishes without being asked to. Which is why we came up with this list of under sink tankless water heater reviews.

Everyone loves warm or hot water and your reason for getting the best under sink water heater is fully backed up in this guide.

Under sink water heaters are also known as point of use water heaters. This device can only supply water at a point of use and will not go any further. So before purchasing one you should know what you are paying for. It can be installed in the kitchen and as well as the bathroom based on your target location.  Most household use these types of water heaters for the kitchen faucet and washing machine to supply instant hot water according to

Why use an under sink water heater?

First reason to even get a water heater for your home is to kill germs running from the taps. If by any chance you have a baby, this water heater will go a long way in ensuring your baby feeding bottles or any other thing that goes to their mouth is properly sterilized. This also applies to adults or kids living in the household as they say health is wealth so get the first thing that will keep you healthy.

Another reason to get these heaters is they are inexpensive as compared to the whole house tankless water heaters. But if a whole house water heater is what you need then go for it. Whole house water heaters are for large homes that need water supply at different locations at the same time within the house. This practically applies to an early morning situation where both you and the kids are taking your bath at different bathrooms.

An under sink water heater can be the end and also the beginning of your troubles if you pick the best based on an experts recommendation. That is why we are here to help you in making that perfect choice for your home. See our top 10 list of the best under sink tankless water heaters. Make your choice at this discounted rates amazon has to offer.

10 Best Under Sink Tankless Water Heater Reviews

DeviceModelFlow RateCustomer Rating(5)Check Price
Ecotouch Tankless Water Heater Ecotouch Tankless Water Heater1.5 GPM3.7check price
Ecosmart ECO MINI 2.5 Gallon 120V Ecosmart ECO MINI2.5 GPM4.3check price
Bosch Tronic 3000 T 2.5-Gallon Electric Bosch Tronic 30002.5 GPM4.4check price
Stiebel Eltron 074050 best Under Sink Tankless Water Heater Stiebel Eltron 0740500.5 GPM4.2check price
Stiebel Eltron 233219 under sink tankless water heater Stiebel Eltron 233219(Editors Choice)2.5 GPM4.5check price
Bosch tronic 3000 Bosch tronic 30002.5 GPM3.4check price
Thermoflow UT10 2.6 Gallons Water Heater Thermoflow UT102.6 GPM4.0check price
Bosch Ariston GL4S Electric Mini-Tank Bosch Ariston GL4S2 GPM3.9check price
Ecosmart POU 3.5 Electric Tankless Water Heater Ecosmart POU 3.5(Most Compact)0.5 GPM3.2check price
Eccotemp EM-2.5 ElectricEccotemp EM-2.5 Electric2.54.4check price

1. Ecotouch Tankless Water Heater – 1.5 GPM

Ecotouch Tankless Water Heater

This is a new model point of use tankless water heater with smart modulating heating. It supplies instant hot water at an optimal thermal efficiency of 98%, and energy cost is a bit minimized. Ecotouch under sink water heater supplies 67°F to 109°F to heat up 1.2GPM of water per minute. It is compact in size, weighing 5.97 pounds and will fit into any under sink. Your home décor is safe with this water heater as it will blend it easily. You can use it in places like strip malls, kitchen and bathroom sinks, doctor’s office, wet bars and a few more.

Features and Capability

Compared to tanked water heaters this device will supply hot water at a instant. It doesn’t store up water which results in bacteria growth and rust in most tanked water heaters. The smart modulating control ensures stable temperature while heating up. It adjusts exact power input according to power calculation based on flow rate.

Depending on your region this water heater will supply hot water based on the temperature of your environment So don’t be surprised if your water isn’t as hot as someone living in a colder region. You can check the flow rate of your location on ecotouch official website or this product page on amazon. It requires a 240V power supply and 10AWG wire size for installation. This sink is mainly for zinc and not for shower purposes. It requires battery to work.

This small tankless water heater requires works at 5.5KW and requires 10 gauge wire and a 30amp double pole breaker to work perfectly. You need brass pipe fitting: A ½ in hex nipple and ½ in coupling to make it easy to hook your cold kitchen line up to the intake.

  • It is compact in design and easy to install.
  • It is energy efficient.
  • It requires 240v power source for best performance.



2. Ecosmart ECO MINI 2.5 Gallon 120V (Amazons Choice)

Ecosmart ECO MINI 2.5 Gallon 120V

This point of use under sink heater is a great choice when buying a water heater. It doesn’t require any expensive installation like costly re-circulating lines and pumps. Just tap into the water line and install directly at the sink. It is light weight and weighs about 15.8pounds, plus it is very compact, which makes it fit into any location. The device comes with a digital output temperature display so you can easy monitor its temperature. It requires just 110V outlet with an amperage capacity of 12Amps to function perfectly. It is the best 110v Tankless Water heater.

Features and Capability

All ecosmart water heaters are 98% energy efficient and this unit is no exception. It comes with a 5 years warranty, so you are safe for the next 5 years. It has a stainless steel tank coated with anti-corrosion and glass lined which allows durability and more extended use. Installation can be a pain if you lack the technical know-how. You can get a professional plumber to install this device for you or call ecosmart to be on a safer side. The manual is quite basic.

The unit requires an extra purchase of a ½ to ½ FIP-MIP brass couplers for water connections or a 2 90 degree ½ female to ½ male adapter. It has a pressure relief valve which eliminates damage during excessive heat and pressure.

  • It requires just 110v outlet to work fine.
  • It is light weight and compact.
  • The unit is a great energy saver.
  • It not easy to install.
  • The manual is quite basic.


3. Bosch Tronic 3000 T 2.5-Gallon Electric Mini-tank Water Heater (Best rated under sink water heater)

Bosch Tronic 3000 T 2.5-Gallon Electric

This point of use water heater has the best features most regular water heaters lack. It is light weight (15.5 pounds) and can easily be hung with its wall bracket, on the shelf or the floor. The water heater has a sleek design which makes it fit into small spaces like under any sink or a cabinet space, plus it will blend with your home décor with ease.

Features and Capability

It provides instant hot water to your zinc and comes with a temperature/pressure relief valve. This release valve is a safety valve that prevents hot water from exploding, thereby regulating its temperature. It comes with an external dial which allows you to adjust it to your desired temperature.

A few people have reported this device leaking water which can be avoided if you follow the instructions carefully. Connect the pressure relief valve for drainage, but if slight moisture escapes the valve you can just use a drain pan or vessel to capture the moisture. If you are using a newer type of faucet, the connection may require an adapter. It does not supply an endless supply of hot water just the 2.5 gallons per use. On the other hand it will reduce lag time while waiting for water to heat up from a distant faucet. Do not turn the thermostat all the way up or it will overheat and turn off automatically. Try using it halfway and it will work just fine.

Energy Efficiency

The water heater has a thick CFC-free foam insulator for maximum energy efficiency and a glass line tank to make it durable. This water heater can also be used in addition to a primary water heating source.  It will save you a lot on electricity bills as it requires just 120V outlet to perform at its best. With a thermal efficiency of 98% and 6 years warranty, you are good to go.

The water heater can be used in a van camper for outdoor activities. Installation is very easy and runs off a standard electric plug.

  • It is energy efficient.
  • It is very durable, up to 6 years.
  • The water heater is very light and fits small spaces with ease.
  • It leaks a little moisture after prolonged use just like an Ac.
  • Does not produce endless supply of hot water.



4. Stiebel Eltron 074050 Under Sink Tankless Water Heater (Best For Smaller Homes)

Stiebel Eltron 074050 best Under Sink Tankless Water Heater

The Stiebel Eltron 074050 tankless water heater is a residential and commercial use type of heater. This heater is German made and built to be solid. It supplies instant hot water while saving you a lot of energy. It requires just 120V outlet to work perfectly. The under sink tankless water heater is light weight (4.6pounds) and can therefore easily fit into any location.

Features and Capability

The heater is maintained by a flow switch, manual reset switch, as well as a thermostat with scaldguard, which ensures water temperature is regulated for safety. It includes a 3 year warranty and can be used in places like residential homes, hotels and motels, restaurants, gas stations, office kitchen and a few more. It doesn’t make noise due to hydraulics installed within it.

This small tankless water heater can only run one shower at a time without problem. Ensure you have a soft or no-soft water softener or the unit might fail.

It requires no maintenance and doesn’t go cold while in use. It has been reported to have lasted for 8 years by a customer. The device has a copper heating coil and a design that is all copper which ensure trouble free service and performance.

  • It weighs just 4.6pounds.
  • It saves you a lot on electric bills.
  • The water heater has a 3 year warranty and lasts a whole lot longer.
  • It can run just one shower at a time perfectly.
  • It requires a water softener for longevity.



5. Stiebel Eltron 233219 2.5 gallon 1300w, 120v SHC (Best Value For The Money)

Stiebel Eltron 233219 under sink tankless water heater

Stiebel electron 233219 water heater is a German made water heater built to stand the test of time. It delivers hot water almost instantly. The water heater is a great energy saving heater that requires 110/120V outlet to work at its best. It is sleek in design and very attractive, fitting into any home décor with ease. The unit Weighs at about 15.9lbs when it is empty, and 38.6lb with water. It can be used in bathroom sinks, laundry areas, cabins, gas stations, food trucks, kitchen sinks and a few more.

Features and Capability

Its tank is built with a world class insulator and requires an 11amp current draw. The water heater has a thermostat dial located at the top for easy temperature adjustment from 86-140°F. You can as well maintain its internal tank temperature above freezing with its special frost protection. Tested and certified by WQA against NSF/ANSI 372 for lead free compliance. Thereby, your safety is guaranteed. It has the fastest recovery time of 18 minutes.

The anode must be replaced every 6 months to enjoy this unit. A few customers have reported it lasted them for up to 10 years without issues

  • It is made in Germany and built to last long.
  • It can use a minimum of 110v outlet.
  • The unit is quite durable.
  • Single point of use water heater.
  • The anode needs to be replaced every 6 months.



6. Bosch tronic 3000 under sink tankless water heater

Bosch tronic 3000

This is another great best under sink tankless water heater that supplies hot water instantly. It is small (5 lb), compact and has a nice design. Bosch tronic 3000 will blend with your home décor with ease. It is also 98% energy sufficient and doesn’t need a relief valve to maintain its temperature and pressure. To enjoy this tankless water heater, make sure it is hard-lined by a professional.

Features and Capability

The electric tankless hot water heater requires a 120V outlet to perform at its best, saving you a little on electric bills. Saving energy due to the fact that it doesn’t store up water at all but rather heats water as it passes through it instantly. It can be used in places like half bathrooms and powder rooms, laundry rooms, garages, pool houses, RVs or boats, kitchenettes, patio sinks and a few others. It is backed up by a limited 5 year warranty on heating element and just 1 year on other components. Less overall maintenance is required.

This unit requires a cold supply line and a water filter attached to it for effective use. Do not try using it for your shower except it is just 1gpm. The small tankless water heater is not thermostatic and so you will always get the same temperature rise. Try not to attach it to a hot water line as a booster. The temperature will drop while running a shower and kitchen sink at the same time.

It supplies clean hot water by using a dual chambered copper heat exchange to supply instant hot water.

  • It supplies hot water instantly.
  • The water heater is light weight, weighing just 5lbs.
  • It is energy efficient as it heats water without storing.
  • Its temperature drops a bit during the cold seasons.
  • It is not thermostatic.



7. Thermoflow UT10 2.6 Gallons Water Heater

Thermoflow UT10 is one of the best under sink water heater to install in your home. This water heater is also German made, which means it will last you for a very long while. It will save you energy and money. It is ideal for places like RVs and Boats, doctor’s office, garage, kitchenettes, small apartments and a few more. The temperature ranges from about 45°F to 167°F, with a frost protection mode suitable for any season.

Features and Capability

The German water heater doesn’t need maintenance to work fine due to its stainless steel tank and EPS foam heating system. This stainless steel has a high efficiency for heating and as a result saves you electricity bills. Has a storage capacity of 2.6 gallons of water to supply hot water quickly with minimum stand-by loss. It weighs 14lbs and is sleek in design, which makes it fit into any location. It wasn’t designed for just under sink application, but can as well be used as a supplement to an existing heater located far from the sink and a buffer for cold water sandwiching.

The unit does not include a breaker and wire so you need to add this to your purchase. On no account should you open the heater cover or the unit while it is still on, this could be harmful. It is hard to install for an average home owner, so get a professional to install this device for you.

Auto cut-off protection

Auto cut-off protection is included in its features as well. This feature will cut off the electric supply to the heater if the hot water temperature is higher than the set temperature to prevent overheating. It will ensure your water heater lasts longer. A safety valve is not needed to install this device. It requires a 120V outlet for work just fine.

If you still prefer a tankless version I advise you go for the Thermoflow Tankless Water heater which works just as perfect as this one.

  • It has an auto cut-off protection feature to prevent overheating.
  • It is quite durable.
  • Can save you a lot on electric bills
  • It does not come with a breaker or wire.
  • Not easy to install by an average home owner.



8. Bosch Ariston GL4S Electric Mini-Tank

Bosch Ariston GL4S Electric Mini-Tank

This is a nice improvement on the Ariston GL4 mini tank water heater that can supply hot water at a go. It is compact in design, weighing 17 pounds and easy to install. Simply tap into the cold water line and install the water heater directly at under the sink. It works with a 120V outlet which makes it an energy saver. This water heater keeps 4 gallons of hot water ready to go and draws just 12.5Amps. A pressure relief valve comes with this bosch heater.

Features and Capability

Bosch Ariston GL4S comes with a thermostat that features a new sensing probe attached to it. This added feature enables it to adjust temperature quicker and maintain consistent heat flow. The installation is quite easy and needs to hard wiring to power it up. It will last you for over 6 years thanks to the glass-lined inner tank used to make it.

Ensure you employ a bosch professional to install this heater to make your warranty guaranteed. The thermostat might pose a little problem when you try to set it. The manual is quite basic. You need to use dielectric water connections to the unit and anode might have to be replaced every 9months.

It works just like a tankless hot water heater by supplying hot water at an instant. The unit works perfectly for kitchen use but I can’t say about showers. It is inexpensive and worth the money.

  • It has a thermostat for easy regulation.
  • It is inexpensive.
  • The unit supplies hot water instantly.
  • It has a 6years warranty which makes it very durable.
  • The manual is too basic.



9. Ecosmart POU 3.5 Electric Tankless Water Heater (Smallest under sink water heater)

Ecosmart POU 3.5 Electric Tankless Water Heater

This is an awesome point of use water heater that can fit into any home. It has a single application and maximum flow rate of 0.5 Gallon per minute (gpm) with a 0.5gpm sink aerator. This aerator will create a non splashing stream while delivering a mixture of water and air. With this water heater you will get an endless supply of instant hot water.

Features and Capability

The hot water temperature might reduce if you don’t slow down the flow of water. It has a one year warranty. It doesn’t work perfectly in a shower due to its low flow rate. The impeller might stop working at some point if it takes in a little dust during installation. You might have to re install it again if this happens. Better still run your water inside the unit to flush any foreign object out before installing it. Ensure you do some semi-annual flushing to keep this unit in good shape. The lowest flow rate the unit allows is 0.45GPM, any lower rate will automatically shut off the heating element. Temperature cannot be manually adjusted.

An added feature is the flow control which enables it to adjust its temperature according to flow rate. It is light weight, weighing about 4 pounds, and the smallest size under sink tankless water heater. It can be used in places like Doctors office, wet bars, boats, bathroom sinks, RV’s and a few others.

The water heater requires a minimum of 100 amp electrical panel for installation with one 30amp single hole breaker which should be connected to a 10 AWG wire. The Ecosmart POU 3.5 requires just a 120V outlet to work perfectly and as a result it saves energy.

  • It saves energy and electric bills.
  • It is the smallest under sink tankless water heater.
  • It requires a 30amp breaker.
  • It can work at just one unit at a time.
  • Not ideal for bathrooms.



10. Eccotemp EM-2.5 Electric

Eccotemp EM-2.5 Electric

This is also a mini tank water heater with a 2.5 gallons capacity, supplying instant hot water to any faucet without waiting. It is small and light weight, which makes it very effective for residential, commercial and industrial uses. The water heater weighs 20pounds.  It can supply hot water for up to two sinks at a time or plumbed to your existing hot water system. It has a manual adjustable temperature control with a 20 minutes recovery time. The temperature ranges from 50°F to 140°F.

Feature and Capabilty

Eccotemp EM 2.5 can operate at a maximum of 150psi water pressure. It can be easily installed and mounted on a wall. A 120volts outlet is all it needs to perform at its best. The unit can be used in places like laundry room, utility sink, garage, office, RVs and a few more. Re-circulating lines and pumps are not needed for its installation. It comes with a temperature and pressure relief valve and an instructional manual.

If you need one for taking showers, I advice you buy the Eccotemp EM 4 gallons unit. This small tankless water heater was designed for just under sinks only. The fittings are made of plastic so handle them with care. The power cable is very short so ensure your outlet is very close to the unit.

  • Can supply hot water at two different locations.
  • It doesn’t require re-circulating lines and pumps.
  • It is quite durable.
  • It has a short power cable.




This top 10 best under sink water heaters are the best ones to choose from for your home. If you are in need of just an under sink tankless water heater which never store up water and supplies hot water instantly go for the Stiebel Eltron 074050 Under Sink Tankless Water Heater. If durability or longevity is what you need, buy the Stiebel Eltron 233219 2.5 gallon 1300w, 120v SHC. On the other hand, if you want something very small based on how small your kitchen is then I advice you go for the Ecosmart POU 3.5 Point Of Use Electric Tankless Water Heater.

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