best water softener for tankless water heater

Top 9 Best Water Softeners for Your Tankless Water Heater in 2023 – A Review & Buying Guide!

Are you looking for the best water softener for your tankless water heater? Hard water can wreak havoc on our homes and appliances, and tankless water heaters are no exception.

If you’re experiencing problems like mineral buildup, scale buildup, and reduced efficiency, then it’s time to invest in a high-quality water softener.

Hard water contains high levels of minerals like calcium and magnesium, among others known to cause scales and buildup inside the water heater – later translating to expensive repairs and replacements.

For people in a hurry – The best water softener for your tankless water heaters is the Whirlpool WHES40E if budget is not the concern. It’s big enough to serve a family of up to 6. If you have well water then the dedicated solution is PRO+AQUA BNDL-WEL which is bundled RO+Filter that is the one-stop solution for your healthy water. If you are on a budget then try this non-traditional and affordable descaler by Yarna.

Fortunately, with the right water softener, you can protect your investment and ensure that your tankless water heater performs optimally for years to come.

In this article, we’ve compiled a list of the top 9 water softeners for tankless water heaters. We’ll go over each one in detail, explaining their features, pros, and cons, and ultimately help you decide which water softener is right for your specific needs.

As a bonus, we have also glued a brief buying guide for an instant crash course on water softeners.

So, whether you’re a homeowner, a plumber, or a DIY enthusiast, read on to learn more about the best water softeners for tankless water heaters on the market today.

REVIEWS: Top 9 water softeners for tankless water heaters

1. Whirlpool WHES40E

Whirlpool WHES40E

40,000 Grain Water Softener

  • Capacity: 40,000 grains
  • Efficiency: Uses up to 75% less salt
  • Household size: Upto 6+ people
  • Maximum water hardness: 125 grains per gallon (GPG)
  • Iron removal: 10 parts per million (ppm)
  • Regeneration:: Demand initiated
  • Flow rate: Super high up to 1-1/4 super high flow valve
  • Water used during regeneration: 3.0 gallons/1,000 grains

The Whirlpool WHES40E super water softener comes first in our list of the best water softener for tankless water heaters. This water softener is a top-quality product designed to combat hard water problems. It comes packed with a range of features, making it an excellent choice for anyone looking for an effective and reliable water-softening solution.

One of the critical features of the Whirlpool WHES40E water softener is its high capacity. It can remove up to 125 grains per gallon of hardness minerals like calcium and magnesium, which makes it perfect for large households or families. The space-saving design of the softener will only take up a little space in your home.

Furthermore, the water softener has an intelligent demand-initiated regeneration system that only regenerates when needed. It helps you save water and salt, making it a more efficient and cost-effective option in the long run.

The Whirlpool WHES40E is relatively easy to install for DIY homeowners with basic plumbing skills. Besides, it’s also compatible with most household plumbing, which makes it an excellent choice for anyone looking for a hassle-free installation process.

Overall, I highly recommend the Whirlpool WHES40E water softener to anyone looking to improve their water quality and reduce the harmful effects of hard water. It’s a must for large households with hard water problems.

  • Highly effective at removing hard water minerals, significantly improving water quality.
  • Affordable compared to other water softeners on the market, making it a budget-friendly option.
  • Easy to install and use, with a user-friendly interface and intuitive controls.
  • Compact and space-saving design, making it ideal for apartments.
  • Some customers have reported occasional leaks or malfunctions, though these are rare occurrences.

2. Aquasure Harmony 64,000 Grains

Aquasure Harmony Series

Water softener for super-hard water

  • High capacity resin
  • Removes up to 64,000 grains of hardness
  • Suitable for households with harder-than-average water
  • User-friendly LCD control panel
  • Easy to install
  • Suitable for families with up to 4 bathrooms

If, for some reason, you aren’t impressed with the Whirlpool softener that we talked about earlier, then check this one out. The Aquasure Harmony 64,000-grain water softener is a reliable and efficient solution for hard water problems. It can reduce the damage to your tankless water heater from the hardest of water. The softener uses advanced technology to remove up to 64,000 grains of hardness, making it ideal for larger households. Whirlpool is designed to provide soft and clean water for all your domestic needs, from showering to laundry.

One of the best things about this water softener is its high-capacity resin. This resin can remove high hardness, iron, and other contaminants from the water supply. It also has a user-friendly LCD control panel that allows you to monitor the system and set up customized preferences. The Aquasure Harmony is also easy to install. You can do it yourself if you have some basic plumbing knowledge.

However, with higher capacity comes a hefty price tag. The Aquasure Harmony 64,000 Grains is expensive compared to other models. However, the cost is justified by its high-capacity resin and advanced features.

The Aquasure Harmony Series 64,000 Grains Water Softener is a reliable and efficient solution for hard water problems. While it may be expensive, its advanced features, high-capacity resin, and positive customer reviews make it a top choice for larger households, especially for super-hard water.

  • Perfect for tough water problems.
  • High-capacity resin for efficient water softening
  • Removes iron and other contaminants from the water supply
  • User-friendly LCD control panel
  • Easy to install
  • It is expensive compared to other models.
  • It may require more frequent resin replacement, depending on the quality of the water supply.



Portable Water Softener – For RV & Small Homes

  • Capacity: 16,000 grains
  • Regeneration time: 30 minutes
  • Flow rate: 4 gallons per minute
  • Resin: High Capacity 8% Crosslink
  • Compatibility: Suitable for RVs, boats, and camping
  • Features: Comes with a handle for easy transport

The On The Go OTG4-VM-DBLSOFT is a portable, compact water softener perfect for RVs, boats, and camping. It helps prevent scale buildup and damage to your motorhome’s tankless water heater and other fixtures.

The water softener comes with a standard double-capacity resin with a total capacity of 16,000 grains, making it suitable for small- to medium-sized families. The resin can also regenerate up to 20 times, meaning you can use it for extended periods without worrying about replacing it. The softener also features a high-flow rate of 4 gallons per minute, so you can quickly fill your water tanks without any delays.

Overall, the On The Go OTG4-VM-DBLSOFT is an excellent portable, compact water softener option. Its double standard resin capacity and high flow rate suit small- to medium-sized families. However, it is expensive and not suitable for larger households.

  • Portable design for travel/camping
  • Protects mobile home tankless heater from lime buildup
  • Reduces hard water minerals, improves water quality
  • Quick, easy regeneration with salt/special solution
  • No electricity or complex plumbing needed
  • Includes quality fittings/connectors for easy setup
  • May not suit big families or long trips.
  • Not recommended for hot water; limiting for some users.
  • Price point may be high.

4. Tier1 Essential 48,000 Grain

Tier1 Digital Whole House Water Softener System

High-Efficiency Digital Water Softener

  • Grain Capacity: 48,000
  • Control Type: Digital
  • Efficiency: High
  • Tech: Ion Exchange
  • Regeneration Type: Metered
  • Salt Saving Technology: Yes
  • Certification: NSF/ANSI Standard 44

Need something affordable yet high capacity without compromising on quality? The Tier 1 Essential Series is the name of the game. This 48,000-grain high-efficiency digital water softener is an excellent option to improve the quality of your home’s water. Designed to remove hard water minerals like calcium and magnesium, the Tier1 48,000-grain capacity softener is sufficient for a medium-sized household of up to 5 people.

One of the things that I liked about this relatively affordable softener is its digital control panel, which makes it easy to program and adjust the settings to fit your specific needs. Besides, the inbuilt bypass valve allows for easy maintenance and regeneration.

The Tier 1 Essential Series effectively solves the common problem of hard water, which can cause skin irritation and dry hair and lead to premature wear and tear on appliances, including your tankless water heater. 

By removing the minerals that cause hard water, this water softener can help extend the life of your pipes and water-using appliances and improve the overall quality of your home’s water.

While it may not be the most affordable option, it removes hard water minerals effectively. It has valuable features like a digital control panel and a bypass valve. However, potential buyers should be aware of the reported issues with leaks and malfunctions and consider professional installation.

  • Digital panel for easy settings adjustment
  • 48k-grain capacity, great for households
  • Includes bypass valve for easy maintenance
  • Efficiently removes hard water minerals, improving water quality
  • Reported leaks and malfunctions by some users.
  • Professional installation recommended, adding to cost.

5. Aquasure AS-HS48D

Aquasure AS-HS48D

Drinking Water Softener + RO and Filter System

  • Soft, scale-free water
  • Built-in RO and filter
  • All-in-one water problem solution
  • Removes up to 99% of contaminants
  • Digital control console
  • Precise backwashing
  • Treats up to 48,000 grains
  • Ideal for 2-4 bathrooms
  • Can efficiently accommodate up to 5 people

The Aquasure AS-HS48D is a powerful water softener with a reverse osmosis and filter system designed to provide soft, scale-free, and spot-free water for the entire household. It can treat up to 48,000 grains of hardness, making it ideal for that fragile tankless water heater to run smoothly for years.

Its digital control is instrumental for parameter controls like time delay, metering, and manual double backwash for superior regeneration, cleaning, and performance. 

As for the RO and filtering, the built-in reverse osmosis and filter system removes up to 99% of water contaminants, ensuring clean, healthy, and crisp-tasting drinking water for the entire family.

Overall, the Aquasure AS-HS48D is an effective and reliable water softener that provides the entire household with soft, scale-free, and spot-free water. The built-in reverse osmosis and filter system ensures clean, healthy, and crisp-tasting drinking water. While the unit may be relatively expensive and difficult to install, its advanced features and high customer satisfaction rating make it a worthy investment for individuals looking for a reliable water softener and filter system for their tankless water heater and other expensive appliances.

  • Soft, scale-free water for the entire household
  • Built-in reverse osmosis removes up to 99% of contaminants
  • Crisp-tasting drinking water
  • Advanced digital control console allows precise backwashing
  • Treats up to 48,000 grains of hardness, suitable for households with 2-4 bathrooms and up to 5 people
  • Expensive compared to other softeners.
  • Professional installation may be necessary.


GE Water Softener System GE Water Softener System

40K Grain Water Softener

  • Capacity: 40,000 grains
  • System type: Salt-based ion exchange
  • Control type: Electronic
  • Regeneration type: Time-initiated, meter-delayed
  • Resin: High-capacity
  • Brine tank: Included
  • Voltage: 110-120V

Based on our study and analysis, the GE GXSH40V water softener ranks 6th in this list of the nine best water softeners for tankless water heaters. However, it still offers some great features and benefits worth considering.

GE uses a resin tank and a brine tank to remove the lime and minerals, which can cause damage to pipes, appliances, and clothing. The water softener can remove up to 95 grains per gallon of hardness, making it ideal for households with fairly hard water up to the 7.0 GPG range. Besides, an equipped bypass valve makes it easy to switch between soft and hard water.

One of the main highlights of the GE GXSH40V is its capacity. The softener has an ability of 40,000 grains, allowing softened water for a household of up to 4 people. The product has a regeneration cycle you can customize based on your household’s water usage. The product can adjust to your specific needs and optimize its performance.

Furthermore, this model also comes with digital controls allowing for convenient handling and real-time information about the water softener’s status. GE also has a built-in WiFi feature that makes it a “smart appliance” and allows you to monitor and control the water softener from your phone or tablet.

The GE GXSH40V Water Softener is an excellent product that can soften hard water for tankless water heaters. While it is higher priced than other water softeners on the market, it offers unique features like WiFi control that may appeal to some buyers.

  • Effective at removing hardness from water
  • Large capacity suitable for households of up to 4 people
  • Customizable regeneration cycle
  • Innovative technology with WiFi connectivity
  • Easy to use and install
  • Higher price compared to some competitors
  • Requires regular resin and brine tank maintenance and replacement
  • May need additional plumbing and electrical work for installation

7. Kenmore 350, 32,000 Grain

Kenmore 350 Water Softener With High Flow Valve

Ultra High-Efficiency Water Softener

  • Grain Capacity: 32,000
  • Type: Single-tank system
  • Resin: High-capacity resin
  • Salt Saving Technology: IntelliSoft2
  • Compact design
  • Certification: NSF International certified to reduce hard water minerals

The Kenmore 350 is another excellent option that you can consider for households of 1-4 people who are seeking an effective solution to hard water problems. 

The water softener uses intuitive IntelliSoft2 technology that adjusts to your household’s water needs, saving you money on salt, water, and energy bills and, best of all, on costly water heater repair.  Do you know how much electricity that tankless water heater of yours uses? The findings will surprise you!

It also features a salt monitor for ultimate efficiency, a high-flow valve that ensures your water pressure remains strong, and a compact single-tank design that provides salt storage and softening in the exact location. 

The Kenmore 350 is NSF International certified to reduce hard water minerals, effectively reducing stains, scale buildup, and clear water iron.

Most people have reported that the Kenmore 350 water softener significantly reduces hard water minerals, stains, and scale buildup, resulting in softer hair and skin and less buildup on fixtures and appliances. 

On top of that, the system is competitively priced, making it an affordable option for households on a budget. But while there have been isolated incidents with the system’s valve, customers have generally been satisfied with the Kenmore 350’s effectiveness, affordability, and ease of installation. 

  • Compact and reliable system
  • Intuitive technology saves money on salt, water, and energy bills
  • NSF International certified to reduce hard water minerals
  • Easy to install
  • Affordable water softening solution that protects your tankless heater.
  • It may not be suitable for households with more than four people
  • Some customers have reported issues with the system’s valve


 PRO+AQUA water softener

Protects Tankless Water Heater from Well Water

  • Resin Capacity: 80,000 grains
  • 5-Stage Water Filtration System
  • Reverse Osmosis Technology
  • Removes 99% of contaminants
  • LED Display for convenient access
  • Compact Design
  • Easy Installation
  • NSF Certified

The well water can be one of the harshest in some US states, costing thousands to repair your lime-affected plumbing and appliances. But no worries anymore. The PRO+AQUA BNDL-WEL is the perfect solution for people looking to remove well water hardness and protect the expensive water heaters. The softener plus RO bundle has an extensive high water flow rate ideal for larger households. Its 80,000 grains of raisin capacity ensures reliable hard water treatment with ease.

The PRO+AQUA BNDL-WEL has a resin tank, brine tank, and control head. The control head is easy to use, and the system is designed for simple installation, with no need for professional help. Its resin tank is made of durable, high-quality materials that ensure long-lasting use.

One of the best things about this water softener bundle is its affordability. Despite its many features, it is reasonably priced and offers excellent value. Customers have reported high satisfaction with this product, with many praising its ease of use and effectiveness.

Overall, the PRO+AQUA BNDL-WEL is an excellent choice for anyone looking for a reliable, effective, and complete water-softening solution for their tankless water heater. Its high water flow rate, large resin capacity, and easy installation make it a popular choice among customers.

  • High water flow rate
  • Large 80,000 grains of resin capacity
  • Reasonably priced water softener and RO bundle
  • Effective at removing hard water minerals
  • Positive customer reviews and high satisfaction ratings
  • It may not be suitable for small households with low water usage
  • Some customers have reported issues with leaks and malfunctions

The most suitable tankless water heaters for well water – if you plan to buy a new heater!

9. Yarna CWD24 Electronic Water Descaler System

Capacitive Electronic Water Descaler System

ALTERNATIVE to Water Softener

  • Weight: 1.05 pounds
  • Water Capacity: Up to 1 inch of the pipe diameter
  • Technology: Capacitive electronic descaling
  • It’s a descaler and not a softener
  • Power Consumption: Less than 5 watts
  • Easy and non-invasive installation
  • Whopping 1-year return policy for 100% return

And there comes the final candidate in our list of the best water softeners for tankless water heaters. It is not precisely a softener either but a descaler (more on this in a minute). If you’re looking for a water softener that works perfectly with your tankless water heater, the Capacitive CWD24 Electronic Water Descaler System is a great option.

The Yarna CWD24 electronic water descaler system helps prevent the buildup of limescale, rust, and other minerals that can damage your tankless water heater and other plumbing fixtures. It uses capacitive electronic descaling technology to soften the water and make it more gentle on your appliances.

One of the key benefits of this descaler system is that it is highly effective. Many people using it have reported significant improvements in water quality, including softer skin and hair, brighter clothes, and reduced scale buildup in their appliances. The system is also more affordable than traditional water softeners, making it an excellent option for those on a budget.

Installation is quick and easy; you can install the system on pipes up to 1 inch in diameter. It is also energy-efficient, with a power consumption of fewer than 5 watts. It is essential to consider a tankless water heater, as it is an energy-efficient appliance. You want to ensure the descaler system you choose doesn’t cancel out those benefits.

Overall, the Yarna CWD24 is an excellent option for those looking for an affordable and effective alternative to traditional water softeners, specifically for use with their tankless water heater. While it may not be as effective for harder than 7 GPG water, it is an excellent choice for those with moderately hard water who want to prevent damage to their plumbing fixtures and appliances.

  • Effective at treating hard water and preventing scale buildup
  • Affordable alternative to traditional water softeners
  • Easy to install on pipes up to 1 inch in diameter
  • Energy-efficient with low power consumption
  • One-year full-blown return policy for 100% return
  • Results may take a few weeks to become noticeable
  • It may not be as effective for tough water with 10+ GPG hardness
  • It does not remove minerals from water; it only prevents the buildup

Save more electricity with these 74 creative ideas that should save you at least a couple of hundred bucks a year.

GUIDE: How to choose the best water softener for your tankless water heater

hard water problems

Choosing the best water softener for your tankless water heater can be confusing. So I wrote you this quick crash course that will hopefully make you reasonably knowledgeable in a minute or two. 

Here are some helpful tips to make the process easier:

  1. Look for a compact and lightweight softener that won’t take up too much space.
  2. Consider the type of regeneration system it uses. A demand-initiated regeneration system triggered by water usage is more efficient than time-based regeneration.
  3. Check the grain capacity of the softener, which determines how much hardness it can remove before needing to regenerate.
  4. Determine if you want a salt-based or salt-free softener. Salt-based softeners are more effective but require regular maintenance to add salt. In contrast, salt-free softeners are low maintenance but are less effective.
  5. Look for a softener that can prevent mineral buildup and clogs, which can damage your tankless water heater.

That said, there are two main water softeners: salt-based and salt-free. Salt-based softeners use ion exchange to remove minerals from the water. Salt-free softeners use a different process called template-assisted crystallization to change the structure of the minerals so they can’t stick to surfaces.

Furthermore, common concerns related to water softeners and tankless water heaters include installation, maintenance, and compatibility. You will want to choose a softener that is easy to install and maintain and compatible with your specific type of tankless water heater.  Just know that even after installing a softener, you should still descale your heater. Less often but still.

Make sure to read reviews and do your research before purchasing to ensure you get the best water softener for your tankless water heater.

Over to you!

Using a water softener is vital for those who have a tankless water heater, as hard water can cause mineral buildup, leading to costly repairs and replacements. 

Among the 9 best water softeners for tankless water heaters we’ve discussed, the Whirlpool WHES40E is an excellent choice for those who want a reliable and efficient water softener. The Aquasure Harmony Series 48,000 is perfect for those with a large household or high water usage. The Go Portable Double Standard Water Softener is ideal for campers who need a portable option. If you need a bundled solution with an RO system, then the Aquasure Fortitude V Series is worth a look. Lastly, the Yarna capacitive electronic water descaler system is a budget-friendly alternative to traditional water softeners.

Each product has unique features, capacity, and price range to cater to different needs and budgets.

I hope this guide on the best water softeners for tankless water heaters helped you make the right choice. Share your experience and questions in the comment below. I am always eager to learn from wonderful readers like yourself.

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