Best Under Sink Water Heaters: Review and Buying Tips

Is an under sink water heater a good solution for your home hot water needs? Find top models to buy for point of use service with the main features. Check out the best-selling tank-type and tankless models including buying tips for a worry-free shopping experience.

Best Under Sink Water Heater

Under-sink water heaters, such as this Bosch Tronic 3000, are small electric appliance designed for instant water heating/delivery at home, office, condo, apartment, cottage, garage, RV, boat, and at the point of service. They are also known as instant water heaters or under a counter water heaters, where the main advantages include space, water, and energy savings when properly installed and used.

They work perfectly as single units, combined with the distant whole-house tank-type unit or installed in-line with an existing tankless water heater, as a buffer, reducing the “cold water sandwich” effect, delivering hot water fast.

Under Sink Water Heaters: Advantages and Benefits

There are two types of under sink water heaters that can be purchased; tank-type such as the Bosch mini-tank Tronic and tankless type such as EcoSmart or Stiebel Eltron that come with less power than the whole-house models but sufficient to heat and deliver water to one fixture/sink.

The tankless type does not contain the water storage tank but provides an endless supply of hot water, while the tank-type has a limited capacity.

One of the greatest advantages of under sink water heaters is instant hot water delivery, saving time, energy, and money. This way you don’t have to run long pipes from the central water heater; just plug this small water heater close to the faucet and enjoy an instant water delivery with a temperature that does not differs from the set one.

By buying high quality under sink water heaters as listed and reviewed here, the homeowner will enjoy the following benefits:

  • Up to 50% in heating cost reduction, including energy and water consumption.
  • These devices can save you money as they eliminate the need for expensive recirculating lines or pumps.
  • Under sink water heaters save water efficiently as they are used where needed, at the point of use; kitchen sink, bathroom, laundry, garage, small cabins, boats and RVs, offices…
  • The product serves one or two faucets max. mainly for doing dishes, hand washing, or shaving.
  • You can choose one of the two different types; tank-type or tankless. Tank type has a limited tank size, usually from 2 gallons, while tankless provides an unlimited water supply but with a restricted flow. Tankless models heat water instantaneously as water flows through the unit, and there is no standby heat loss.
  • Under sink water heaters are small, lightweight and compact that don’t occupy too much space.
  • They are easy to install due to the availability of a quick installation guide.
  • They can be wall mounting or floor standing.
  • The product is very reliable, safe, and energy-efficient.
  • They have compact bodies and other easy-to-use features.
  • They offer safety features for reliable and safe operation.
  • The desired temperature of the outgoing water can be set by using the temperature dial.
  • Cheap to buy.

Popular Under Sink Water Heaters to Buy

EcoSmart ECO 11

Ecosmart Eco 11 (photo:

EcoSmart ECO 11 is a tankless electric water heater that utilizes one high-power heating element, designed to provide up to 13 kW of heating power, and thanks to the advanced self-modulating technology, are able to control how much energy will be used.

The unit utilizes a control panel with the adjustment knob/temperature control so the users can easily set the temperature between 80 F and 140 F and the digital temperature display to check and monitor.

Due to its small size of 11.5″x8″x3.75″, lightweight design of 6.5 lbs, wall-mount installation, and water delivery of up to 2 GPM, the EcoSmart water heater is ideal for small homes and apartments – or point of use applications.

Looking at the user reviews, they were mainly positive (4.2 of 5). Users were happy with the unit’s performance, the consistent temperature of the outgoing water, and savings. For the proper work and to avoid hassle and failure, it is recommended to have all the electrical requirements met. As some users suggested, hot water is possible to get, but the water flow has to be reduced and incoming water not too cold, otherwise, it wouldn’t be high as expected. The unit is small, easy to install, even replace elements.

EcoSmart ECO 11 is a good buy, not only because of its great features, fancy look, and small size, but because it saves energy (up to 50%), offers a lifetime warranty, and has many positive reviews.

Bosch Tronic 3000 T

Bosch Tronic 3000 (photo:

Bosch Tronic 3000 T – model ES2.5 is one of the top-selling electric mini tank-type water heaters that are designed for installation under the sink or in cabinets, in small apartments, RVs, and boats, garages…

Here are the main features:

  • Attractive and modern look.
  • Small (13.75 “x13.75″x10.75”) and lightweight (15.5 lbs) design.
  • The single installation can also supplement a large tank-type water heater to deliver water fast or in-line with the tankless unit for continuous supply.
  • Simple 120 V plug-in connection.
  • Flexible floor, shelf, or wall mount installation.
  • It is equipped with an external dial for temperature control from 65 F to 145 F.
  • It uses one heating element with a power of 1440 W. Recovery rate is 6.8 gallons per hour.
  • 6-year warranty.

Pros and cons: Bosch Tronic 3000 T is an excellent solution for people who are looking to avoid long wait times from the distant water heater. It comes with a good manual which makes the hookup simple. The heater requires a dedicated electrical outlet. Hot water from a 2.5-gallon tank doesn’t last long (few minutes only), but it is good enough for small jobs such as hand and face washing – and it takes less than 10 minutes to warm it up again.

Buying Tips

When buying a quality under-sink water heater, first check the popular and well-known brands with a good reputation and years of experience, such as; Bosch, EcoStar, Stiebel Eltron, Rheem…

Also, take into consideration the following:

  • Water flow rate (bathroom faucet allows an average 0.5 GPM; shower 1.5 to 3.0 GPM)
  • Incoming groundwater temperature
  • Recovery rate
  • Activation flow rate
  • Heating power in kW
  • Available features such as the modulation, conveniently located thermostat, a relief valve for safety
  • Price and warranty

And, of course, make sure that your home has all the necessary hookups and meets the electrical requirements for installing the electric water heater.


Under sink water heater is a good buy for those homeowners who need hot water delivered fast, mainly for smaller water jobs such as hand washing or dishes, as it saves time, water, and energy.

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