The Best Water Heater for Hard Water

Water Heater
Water Heater

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

The Best Water Heater for Hard Water

Top 6  Reviews

1. EcoSmart ECO 11 Electric Tankless Water Heater

This tankless water heater will help you save up to 60 percent on 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 any small point-of-use application. The company designed it to heat up to 2 gallons of water per minute and is optimal in temperatures of 67 degrees and above.

Save money and energy by getting a water heater that only turns on when you need hot water. The sleek, wall-mounted design will free up floor space for more storage!


  • Heats up to 2 gallons of water per minute
  • Sleek, wall-mounted design
  • Only turns on when you need hot water
  • Lifetime warranty


  • 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 designed to fit directly under your sink. It provides hot water on demand 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 wall-mounted or floor-mounted. The operating water pressure goes up to 150-psi (pounds per square inch) so you can get maximum pressure for your sink or shower. Don’t waste your time with inefficient large water heaters when a small on-demand water tank will do the job.


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


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

3. Ariston Andris 2.5-Gallon Corded Mini-Tank Electric Water Heater

The compact design of this mini-tank water heater provides instant hot water at the point of use. It can hold up to 2.5 gallons of water and can be mounted on the wall or on the floor.

This corded tank easily connects to a standard 120-volt outlet. With a 6-year limited warranty on the tank, this water heater will provide you with on-demand hot water when you need it at your point-of-use location.


  • 2.5-Gallon capacity
  • Corded for connecting to a standard 120-volt outlet
  • 6-year limited warranty on the tank


  • Installation instructions are not very clear

4. Rinnai V65iN High-Efficiency Tankless Hot Water Heater, Natural Gas

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

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


  • 10-year warranty on the heat exchanger
  • 5-year warranty on parts
  • Operates with natural gas
  • Delivers up to 6.5-GPM


  • Requires a special vent system for the natural gas

5. Stiebel Eltron Tankless Water Heater Tempra 24 Plus, Electric

The technology for this tankless water heater automatically maintains water temperature for consistent comfort. It will reduce the water flow slightly if the hot water demand exceeds the capacity. This prevents the hot water from being interrupted in the middle of your shower.

There is a digital temperature display on the front of the tank which includes preset temperature memory buttons. This specific model requires a minimum recommended household electric service of 150-amps and offers water temperatures up to 140 degrees.

With 7-year leakage and 3-year parts warranties, this tankless water heater is a must-have for your home.


  • Digital temperature display with preset buttons
  • Automatically reduces water flow if hot water demand exceeds the capacity
  • Small, sleek profile
  • No venting required


  • Not recommended for a full-house hot water supply

6. Ariston GL4S Electric Mini-Tank Point of Use Water Heater

This is a 4-gallon mini-tank water heater that provides instant hot water for your sink’s faucet. There is no hard wiring required. You can simply plug it into an electrical outlet. This tank can be installed independently or it can be installed as a booster to a larger water heating source.

This mini-tank comes with a 1-year limited parts warranty and a 6-year limited heat exchanger warranty. If you need a simple hot water solution for a sink, this mini-tank is cost-effective and has a small footprint.


  • 4-gallon capacity
  • No hard wiring needed
  • 6-year limited heat exchanger warranty
  • 1-year limited parts warranty


  • The warranty requires a Bosch-authorized plumber to diagnose the problem

Frequently Asked Questions

Q: What Is The Best Type of Water Heater for Hard Water?

A: If you are concerned about mineral deposits in your hot water heater, then the best solution is to go with a tankless heater. With tankless heaters, there is no reservoir for storing heated water. Therefore, there is no place for mineral deposits to settle and no concerns about damage to the water heater.

Another option is a traditional hot water heater with a tank, but you will need to treat the water and periodically clean out the tank to get rid of mineral deposits.

Q: What Size Water Tanks Should I Buy?

A: The size of the tank you need depends on your hot water usage volume. Tankless water heaters are the most common but are typically not energy efficient. Tankless 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 the type of tank to purchase.


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

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