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The Top 5 Best Under Sink Water Heater Choices On the Market

Jennifer Hansen
Last Updated on
by Jennifer Hansen

If you’re looking for the best under sink water heater, our recommendations include products from different manufacturers and space-saving designs that fit well in even the most compact areas.

These under sink water heater reviews highlight efficient models that offer excellent performance and reliability with easy installation.

Best Under Sink Water Heater
  • Total Capcity (Gallons): 4
  • Dimensions (inches): 13.75 x 13.5 x 13.75
  • Weight (lbs): 17.3
  • Total Capcity (Gallons): 2.6
  • Dimensions (inches): 18 x 11 x 12.2
  • Weight (lbs): 14.72
  • Total Capcity (Gallons): 2.5
  • Dimensions (inches): 11.75 x 17.25 x 10.38
  • Weight (lbs): 20
  • Total Capcity (Gallons): 0.67
  • Dimensions (inches): 12.06 x 8.38 x 14.62
  • Weight (lbs): 7
  • Total Capcity (Gallons): 2.5
  • Dimensions (inches): 16.2 x 11 x 11
  • Weight (lbs): 15.8

The Best Under Sink Water Heaters We Recommend

1. Bosch Electric Mini-Tank Water Heater


The Bosch Electric Mini-Tank water heater is a visually appealing option and ideal for spaces where looks matter or where there are two sinks. It features a single dial for adjusting the temperature of your water and a 4-gallon tank for instant hot water. This unit is 98 percent efficient and measures 13.75 inches wide by 13.75 inches high and 13.5 inches deep, making it about the size of a milk crate.

The Bosch Mini water heater has a glass-lined interior to prevent water from leaking from the storage tank and help maintain efficiency. One drawback is that if this unit gets dropped, the glass lining could break, which would render the item unsuitable for installation.

You can get enough water from this device to supply up to two sinks with hot water, but once the hot water runs out, you’ll be relying on your whole-house water heater as usual. The insulation in this unit is CFC-free foam for added durability and excellent insulation.

  • Mounts to the wall or floor
  • Extra-long 36″ cord
  • Supports two sinks with hot water on demand
  • Glass-lined for a longer useful life
  • Connectors begin to wear out over time
  • Dropping this unit before installation can break the glass tank and cause leaks

2. Thermoflow UT10 2.6-Gallons Electric Under Sink Water Heater


The Thermoflow UT10 mini tank water heater makes DIY installation easy while also adding some safety features so you can feel confident the unit gets correctly installed. This device has an Active Protection Circuit that ensures a proper connection to the electric supply so the unit won’t overheat and become a fire hazard.

There is also a Thermostop function and an energy-saving standby mode that limits the power consumption and allows you to set the exact temperature for your water. In addition , there’s a frost protection mode that you can use in any season and a maximum temperature of 167-degrees Fahrenheit.

The safety valve on this mini water heater is newly designed, and you can mount this device to any wall or base cabinet since it weighs only 14 pounds.

You’ll need to fill this water heater with water before you connect it to an electrical source. There are comprehensive instructions included to walk you through the process of installation using the connectors, bushings, and valve that are part of the package.

  • A stainless steel tank and heating element
  • Energy-efficient standby mode
  • Upgraded relief valve for added safety
  • Active protection prevents the unit from overheating
  • Control dial options are unclear
  • Small capacity

3. Camplux ME25 Mini Tank Electric Water Heater


The Camplux Electric water heater is a versatile product suitable for indoor and select outdoor applications while also including several safety features.

This device is a good option for vacation homes and other unique applications as it features IPx24 waterproofing and freeze protection for added durability. You’ll also notice the added safety features that make this mini water heater a good choice, including a CSA listed temperature-and-pressure relief valve and an overheat protection feature.

The exterior of this mini water heater is mostly white with a silver operation panel, making it easy to blend into your existing decor. This heater measures 17.25 inches high by 11.75 inches long and 10.38 inches deep to fit in most compact spaces, and it weighs 20 pounds, so it’s easy to mount in a variety of locations.

  • An extra-long 43.3-inch power cord
  • Thermostat control for better energy savings and safety
  • Mount it to the wall or set it on the floor or a shelf
  • Includes a Temperature and Pressure relief valve for added safety
  • Limited online support for this product via the Camplux website
  • Too small for larger kitchens or bathrooms

4. InSinkErator HOT150 in Satin Nickel


The InSinkErator HOT150 instant hot water dispenser is an ideal addition for areas of your home where you need hot water for making beverages or other light applications. This device can produce up to 200 cups of water that is 200-degrees Fahrenheit or near-boiling, and it comes with a 1-year-in-home limited warranty.

The installation process for this product claims to be tool-free and certified to be frustration-free or as easy as possible. Still, the packaging may not contain all of the necessary parts that you’ll need for a successful installation.

The spout measures 6.25 inches tall and reaches out just over 5 inches from the base, so it’s a rather compact presence on your countertop and can sit discreetly next to a sink faucet. The portion of the unit that sits under your sink measures 12.06 x 8.38 x 14.62 inches and weighs around seven pounds.

  • Can produce up to 200 cups of near-boiling water per hour
  • The installation requires no tools
  • Easy to adjust the temperature using a single dial
  • Easy to use spout with a satin nickel finish
  • The packaging does not include all the parts you’ll need for installation
  • Sputters before hot water comes out

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


The Ecosmart ECO Mini electric water heater sits comfortably under any of your sinks and features a single dial that allows you to set the water’s temperature. An indicator light on the front of the device lets you know when it’s heating your water, and you can get up to 6 full gallons of hot water before it needs some time to reheat.

You can also control the flow on this under sink water heater and power it on either a dedicated 15-amp circuit or a 20-amp shared circuit. After you install this water heater, it will provide you with hot water on demand until it runs out, and then the hot water comes from your whole-house water heater as usual.

  • 8% energy efficient
  • Manufactured in the United States
  • Easy to adjust settings with a single dial
  • Does not work on a 12-volt battery system
  • Can be an additional expense if you do not have a grounded socket to plug into

The Advantages of Under Sink Heaters

There are many distinct advantages to using an under sink water heater, and a hidden water heater will efficiently heat your water without taking up a lot of space. However, the benefits don’t stop there, and under sink water heaters are quickly becoming more popular for a variety of reasons.

Energy Efficiency

The Energy Star website lists water heaters as the second most demanding source of energy consumption in your home, which means that getting a more efficient water heater could improve your energy usage and lower your utility bills.

These small devices are more energy-efficient than large heaters with a tank and take seconds to heat your water. Under sink heaters also result in less wasted water since the water that comes out of your tap is heated closer to the faucet and gets hotter sooner.

With a traditional water heater, the water has to travel through your pipes for some distance, and this can cool the water more during colder months. As the water travels through your pipes, there is also a higher risk of picking up contaminants and other impurities that can impact its quality.

When you opt for an under counter water heater, you aren’t settling for lesser performance, and these units are compatible with a variety of fuel types. With periodic maintenance, you can also enjoy your tankless unit with a minimal amount of efficiency lost.

Tankless heaters also don’t have a pressure relief valve, which means a higher amount of thermal efficiency and safety with less energy consumed overall.

Get Hot Water Fast

With an under sink water heater, you can enjoy almost unlimited hot water without the risk of contamination that is possible with heaters that have a water storage tank. Since the water heats up in seconds, you’ll also waste less water waiting for hot water to come out of the tap, and you can save on water heating costs in the process.

If there’s a place in your home where you frequently use hot water, an under counter water heater can save you time and money. Many use these compact units in their kitchen to get instant hot water for dishes, cooking, and making hot beverages.

These units also make sense in other areas of the home, including wet bars, bathrooms, utility rooms, and laundry rooms. If your laundry room is in your basement or on the first floor of your home, the ideal location for a larger tankless water heater is the second floor. Still, these smaller models can go anywhere without sacrificing efficiency.

Some under counter water heater options feature a faucet that sits above the counter and to the side of your current sink. These models are ideal for filling cups or mugs with hot beverages without changing how you use your current faucet.

Maintenance and Longevity

You also don’t have to clean an under sink water heater as often as a traditional water heater, and the installation is far less complicated. In about an hour and with some basic tools on hand, you can install your own under counter water heater and enjoy using up to 25 percent less water in many situations.

Maintaining your under sink water heater is an easy process, and you can clean the exterior of the device with a damp cloth as needed, but there’s no need to flush the water out of it once a year like you would with conventional water heaters. If your water is hard, you may need to check various parts of the water heater more than once a year, but it is easy to do.

You’ll want to look at the electrical parts of the under sink water heater to verify they are still attached, clean, and undamaged. You’ll also look for evidence of water leaks near the unit where the pipes join together as these are the weak points of the system.

Lastly, pipe blockages do happen more often with hard water, and you might need to flush the pipes with a cleaner or water softener product a few times a year if you experience problems. To clear a blockage, you can also use a plumbers snake or drain cleaner, but blockages are less common if your water gets treated with a softener.

Large tankless heaters meant to heat water for your whole house have a lifespan of about 20 years, and traditional heaters with a tank have a lifespan of around 8 to 12 years, but these smaller units don’t last as long with regular use.

The warranty on these devices is 2-3 years in most cases and covers parts that are the most likely to need attention. Despite this shorter lifespan, these units are cost-effective and highly reliable even if you need to replace them every 3-5 years.


Types of Under Sink Heaters System

Under sink heaters come with tanks or without, and you can also find on-demand hot heaters that feature a spigot that installs next to your current faucet. The housing of these water heaters will vary based on their type and the brand, and the size also varies.

Some of these heaters feature a spigot that is ideal for single servings of hot water for beverages, while others have a higher capacity that makes them ideal for use in bathrooms and cooking. These models sometimes feature the name Point of Use or POU models.


Important Pre-Purchase Considerations

As you consider your buying options for the right under sink water heater, take a look at our list of considerations to evaluate the best features and options for your needs.

Tank or Tankless Designs

Some mini hot water heaters meant to sit under your sink come with a tank while others will be tankless and heat your water on demand. Even heaters with a tank will heat water on demand, but they also store the water at a higher temperature than your home to make getting hot water faster and easier.

Tankless designs tend to be pricier than designs with a storage tank, but don’t let this dissuade you from choosing one of these models. Many individuals find tankless designs small enough to fit in more compact areas of their homes. They also like the additional energy savings they get from not maintaining the water tank’s temperature.

Water heaters for under sink applications frequently have a small tank, and this will allow you to have hot water still even when you have no power in your home.

These water heaters use the water left in the tank, and if you choose one with a power source other than electricity, you can enjoy your hot water out of the tap even when your power is out.

There are also some visual differences between a mini water heater with a tank and one without a tank. The tankless heaters tend to be smaller and more compact, making them ideal for areas where they might be seen or not hidden in a cabinet. However, heaters with a tank also feature pretty exteriors that can blend well into any decor.

Sizing and Your Space

Before selecting a mini heater, you’ll want to see what kind of space you have under your sink, and how much of that area you are willing to dedicate to this device.

Keep in mind that some under sink heaters require a specific amount of clearance to prevent fire hazards and other issues. You can generally find this information on the product page for that item or online.

The size of an under sink heater will vary from brand to brand, and you must get one with a tank that not only fits your space but also delivers the amount of hot water you need to save time and energy. Mini hot water heaters can have tanks that range from around two gallons to seven gallons on average, although all sizes are readily available.

You’ll also want to consider what else you’ll be putting near the water heater. These devices do handle electricity and water, so it’s a good idea to move items that can be damaged by the device.

It’s not uncommon for older water heaters reaching the end of their useful life to leak, and you’ll want to keep items clear to avoid water damage.

Flow Rate and Capacity

If your hot water heater for under your sink has a tank, you’ll want to think carefully about the size of the tank that you choose and opt for one that is large enough for your use, but not so large that you negate the cost and energy savings.

Larger capacity water heaters can have tanks that hold around seven gallons, and these are ideal for sinks that are shared with multiple people, or utilized by more than one sink.

The flow rate of your device will determine how much hot water is released and how quickly the hot water heater will need to replenish its water supply.

Many tankless water heaters offer an unlimited supply of hot water without relying on your whole-house water heater. Still, heaters with a tank will eventually empty, and you’ll be using hot water from the larger water heater for your home.

Higher flow rates will allow you to get more hot water at any given time, but that might also require your under sink hot water heater to re-warm water more frequently, and this requires additional energy.

Tankless water heaters will heat the water when you need it, which is more efficient, but they also require a greater amount of clearance and are usually more costly.

Energy Efficiency Rating

Most water heaters meant for under your sink will come with an energy efficiency rating, and you can use this to determine how well your device will use energy to maintain or produce hot water.

The standard for most appliances is the EnergyStar rating, which gives your device a score, so you know how efficient it is, and generally, small heaters rank highly.


Most water heaters that fit under your sink will have a single dial for simple controls to adjust their setting and operation. In most cases, all you’ll need to alter on your mini water heater is the temperature of the water that it produces, and a simple dial performs this task nicely.

Some water heaters will also feature an indicator light, so you know when they are on and heating up water. This light is helpful when you’ve used up all the hot water and want to know what the device is doing. Many heaters also feature an array of safety features and ways to prevent the water from freezing when the heater is not in use.

Warranty and Durability

In general, you’ll want to select a mini water heater with a longer warranty as this often speaks to its overall durability. You should avoid devices with a single year warranty or a highly limited warranty as they may fail earlier than a unit with a warranty of 2-3 years. Some of the best warranty units feature up to a 6 year timespan. There are also some units that have lifetime warranty coverage that may give you great peace of mind.

You may pay more for an extended warranty, but this small price difference is often negligible when you compare it to the luxury of unlimited hot water in your home where you need it. Most users do not regret paying slightly more for a higher quality under the sink water heater, but there are other factors to consider, such as the type of materials used.

Many under sink hot water heater designs feature a glass tank, which is excellent for preventing leaks and provides additional longevity to the unit. Unfortunately, if you drop this unit while installing it, the tank can break and render the unit unusable.

Before purchasing a unit with a glass tank, carefully inspect it to ensure that it is intact and not shattered. Once installed, the glass tank should last longer than a stainless steel tank and provide better insulation.

Others Things to Consider

It’s useful to understand the type of heating system that the unit you’re considering is leveraging. There are different heating system designs and they do make an impact when it to the unit acting as an instant water heater. The instant water feature might be something you really would enjoy and become a requirement. Especially if you are impatient with water temperature taking too long to reach your desired state.

It’s also good to note the tank type, such as those that feature a glass lined tank. Obviously, with an under sink tankless water heater, this point is moot. Obviously, if compact design means a smaller gallon mini tank. This should, necessarily, impact the gallons per minute that the overall system is capable of providing to you.

However, you certainly should understand the recovery rate, waiting time, and temperature control to make sure that the system is going to meet your fundamental expectations and needs.

Brands, as always, are something to pay attention to, as well. Some names are well known in the industry, such as Bosch and Stiebel Eltron. And, they are market some features unique to their brand, such as Bosch Tronic or tronic 3000.

Also, you’ll need to decide if the electric tankless water heater you put under your kitchen sink needs hard wriring or if it can be simply plugged into an outlet under your kitchen sink area. If hard wiring is required, that may mean it won’t be a DIY project and you’ll need some professional help for the installation.

Final Thoughts

Selecting the best under sink water heater for your home can help save you time, water, and money, but most people tend to notice how luxurious it is to have instant hot water.

Although these units come in many capacities and shapes, these types of units are reliable, perform well, and are appliances you can install yourself. Consider these under sink water heater reviews to get you started.

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About Jennifer Hansen
Jennifer Hansen
Jennifer is a mother of 2 and has always been a careful shopper, determined to make the best buying decisions for her family. She loves researching the marketplace to find the right products for her household. She leads a small but mighty team of writers in bringing you WaterFilterSpot.
Jennifer Hansen
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