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Water Softener After Water Heater Installation. Is It Necessary? What You Should Know!

Water Softener After Water Heater Installation. Is It Necessary? What You Should Know!

Home water quality and heating system decisions require many considerations, with tankless water heaters often chosen due to on-demand hot water availability as well as cost savings; yet an often forgotten aspect is whether to add an optional softener system with their tankless unit.

water softener and tankless water heater

This comprehensive guide explores all of the fundamental aspects of water softeners and their compatibility after tankless water heater installation in Greenville, SC, answering crucial questions such as “Does a tankless water heater need a water softener?”, “how does a water softener affect your hot water heater,” “Does a water softener ruin a water heater?” etc. Our goal is to equip you with all of this knowledge to make informed decisions regarding both home water quality and heating system management systems.

Let’s shift to our main topic!

Water Softener Systems and Their Function

Water softeners are designed to eliminate hardness minerals like calcium and magnesium from household water supplies, including those found in hard water sources like rivers. Hard water often contains high concentrations of these elements, which can contribute to issues like scale formation in plumbing fixtures and appliances, soap scum deposits on surfaces, and decreased efficiency for hot water heaters.

Water softeners serve a vital function by exchanging hardness minerals for sodium ions through an ion exchange process, eliminating hard water deposits from drinking supplies and improving overall taste and comfort.

Now, let’s address the primary question: Does a tankless water heater need a water softener?

Does a Tankless Water Heater Need a Water Softener?

Considerations when pairing water softeners and tankless water heaters depend upon various variables, including local water quality and personal preferences. Here, alongside the benefits of tankless water heater we examine their pros and cons so that you can make an informed decision.

Pros of Using a Water Softener with a Tankless Water Heater:

Scale Prevention: Installing a water softener will help avoid scale accumulation in your tankless water heater’s heat exchanger and thus protect its efficiency over time and potentially save costly repairs in the future.

Extended Lifespan: Softened water can protect internal components from corrosion and wear and tear, thus increasing their lifespan for better long-term value.

Improved Performance: Softened water heats more efficiently in tankless water heaters so that you reap all the advantages offered by their energy savings capabilities.

Reduced Maintenance Costs: With a water softener in place, your tankless water heater may experience reduced maintenance issues related to scale buildup, saving both time and money in the process. This may reduce maintenance needs over time.

Energy Savings: Because tankless water heaters operate more efficiently with softened water, you could experience significant energy savings on utility bills. Softened water enables faster heating times and reduced energy use compared to using hardened water as the basis of operation.

Hope now you have an answer to how a water softener affects your hot water heater. Let’s move to another section, i.e. cons of water softener installation.

Cons of Using a Water Softener with a Tankless Water Heater:

Initial Cost: Installing a water softener into your home involves upfront expenses for purchase, installation, and ongoing maintenance costs.

Sodium Content: Water softened with sodium may not be appropriate for people following diets with specific sodium restrictions.

Maintenance: Water softeners require regular upkeep, including adding salt to their brine tank and cleaning or replacing their resin bed on occasion.

Installing a Water Softener Before or After a Tankless Water Heater

Another important consideration is whether to install the water softener before or after the tankless water heater in your plumbing system. Again, the choice depends on several factors, including your water hardness levels as well as the specific needs of your household. This choice can be discussed with a professional water softener and tankless water heater expert in Greenville just like the Tri-State Plumbing. 

Installing Before the Tankless Water Heater:


  • Prevent scale buildup in your heat exchanger for efficient operation. 
  • Protect all appliances and fixtures using water throughout your home from possible harm caused by hard water conditions.
  • Softened drinking and bathing water.


  • Increased upfront installation costs.
  • Requires additional space.

Installing After the Tankless Water Heater:


  • Lower initial installation costs. 
  • Takes up less space when installed into plumbing setups. 
  • Protects tankless water heater but may not necessarily shield other fixtures.


  • The tankless water heater may still accumulate scale, potentially alleviating efficiency.
  • Water softening or appliances, as well as fixtures downstream from the unit, may not be as efficacious.

Closing the Faucet on Doubts

As you consider adding a water softener system to your tankless water heater, be sure to assess water hardness levels, select an appropriate type, and decide where you would like it installed, either before or after. By making informed choices, you can help guarantee years of efficient hot water on demand from your heater. Plumbers in Greenville, SC at Tri-State Plumbing can help you make the right decision regarding water softeners with tankless water heaters. Contact us now if you have any doubts!

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