6 best water heaters for hard water in 2020 reviews

If you have hard water at home, you’ve probably wondered what the best hard water heater is. We have done some research for you. Here you will find reviews of several water heaters that work well with hard water and are a significant asset to your home.

Water heater for hard water

1.Electric instantaneous water heater EcoSmart ECO 11

With this water heater you can save up to 60 percent of your water heating costs. This EcoSmart water heater features patented self-modulating technology and design, making it 99.8 percent energy efficient.

The ECO 11 series is ideal for small apartments or small point-of-use applications. The company designed it to heat up to 2 gallons of water per minute and is optimal at temperatures of 67 degrees and above.

Save money and energy by buying a water heater that only turns on when you need hot water. The slim design on the wall creates space for more storage space!


  • Heats up to 2 gallons of water per minute
  • Slim wall design
  • Turns on only when you need hot water
  • Lifetime guarantee


  • It is difficult to contact customer service

2. Bosch Tronic 3000 T 7-gallon electric mini tank water heater

This is an electric mini tank water heater that fits right under your sink. It delivers hot water when you need it and can store up to 7 gallons of hot water.

This tank can be installed either vertically or horizontally and it can also be mounted on the wall or on the floor. Operating water pressure increases to 150 psi (pounds per square inch), giving you the maximum pressure for your sink or shower. Don’t waste your time with inefficient large water heaters when a small water tank does the job when needed.


  • Mini tank design
  • Stores up to 7 gallons of water
  • Taps directly into the cold water supply line
  • Wall or floor mounting


  • Does not provide enough pressure for a shower or a booster for a tankless heater

3. Ariston Andris 2.5 gallon cable mini tank water heater

The compact design of this mini water heater immediately delivers hot water on site. It can hold up to 2.5 gallons of water and can be wall or floor mounted.

This corded tank can be easily connected to a standard 120 volt outlet. With a 6-year limited warranty on the tank, this water heater will provide you with hot water when you need it when you need it.


  • 2.5 gallon capacity
  • Cable for connection to a standard 120 volt socket
  • 6 year limited warranty on the tank


  • Installation instructions are not very clear

4. Rinnai V65iN high performance water heater, natural gas

The Rinnai V65iN is a water heater that runs on natural gas. This heater is for indoor use only and can deliver hot water flow rates of up to 6.5 GPM (gallons per minute).

You can control this sophisticated instantaneous water heater from a mobile application that allows you to set timers and schedules throughout the day. You can even put the system into vacation mode when you are away from home for several days. If you want endless hot water for your entire home, you should consider this instantaneous water heater!


  • 10 year guarantee on the heat exchanger
  • 5 year parts guarantee
  • Works with natural gas
  • Delivers up to 6.5 GPM


  • Requires a special ventilation system for the natural gas

5. Stiebel Eltron instantaneous water heater Tempra 24 Plus, electrical

The technology for this instantaneous water heater automatically maintains the water temperature to ensure even comfort. The water flow is slightly reduced if the hot water requirement exceeds the capacity. This prevents the hot water from being interrupted in the middle of the shower.

There is a digital temperature display on the front of the tank with preset temperature storage buttons. This particular model requires a recommended household electrical power supply of at least 150 amps and offers water temperatures of up to 140 degrees.

With 7 years of leakage and 3 years of parts warranty, this instantaneous water heater is a must for your home.


  • Digital temperature display with preset buttons
  • Automatically reduces water flow when hot water demand exceeds capacity
  • Small, slim profile
  • No ventilation required


  • Not recommended for hot water supply throughout the house

6. Ariston GL4S electric mini tank water heater

This is a 4 gallon mini tank water heater that instantly delivers hot water to your sink faucet. Fixed cabling is not required. You can simply plug it into an electrical outlet. This tank can be installed independently or as a booster for a larger water heating source.

This mini tank comes with a 1-year parts warranty and a 6-year heat exchanger warranty. If you need a simple hot water solution for a sink, this mini tank is inexpensive and takes up little space.


  • 4 gallon capacity
  • No fixed wiring required
  • 6 year limited warranty for heat exchangers
  • 1 year limited parts warranty


  • The warranty requires an installer authorized by Bosch to diagnose the problem

frequently asked Questions

F: What is the best type of water heater for hard water?

A: If you are worried about mineral deposits in your water heater, the best solution is to use a water heater. With instantaneous water heaters, there is no storage container for storing heated water. Therefore, there is no room for mineral deposits and no concerns about damage to the water heater.

Another option is a conventional water heater with a tank. However, you need to treat the water and clean the tank regularly to remove mineral deposits.

F: What size of water tanks should i buy?

A: The size of the tank required depends on your hot water consumption. Instantaneous water heaters are the most commonly used, but are generally not energy efficient. Instantaneous water heaters are more energy efficient, but may not supply enough hot water for multiple use points at the same time. Determine what your typical usage pattern is and this will help you decide which type of tank you want to buy.


When it comes to water heaters, there are many options on the market. If you want to get the best hard water heater, the bottom line is to consider a tank-less option, as there is no reservoir where mineral deposits can accumulate.

Best water heater for hard water

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