Does a Whole House Water Filter Soften Hard Water?

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Hard water is one of the most common and annoying water quality issues, so it would be helpful if a whole house water filter could soften water and filter out contaminants.

In this guide, we’ve answered the question, “Does a whole house water filter soften water?” We’ve also shared information on how whole house water filters work compared to traditional water softening methods.

πŸ“Œ Key Takeaways:

  • Whole house water filters DO NOT soften water.
  • The role of a water filtration system is to remove contaminants from water, and most filters aren’t designed to target hard water minerals.
  • If you have hard water, you’ll need an official water softener or water conditioner to treat the problem.

🚰 Do Whole House Water Filtration Systems Soften Hard Water?

No, whole house water filtration systems don’t soften hard water.

Whole house filters aren’t designed to tackle hard water. Instead, these systems use a filtration media to trap contaminants like chlorine, heavy metals, and nitrates.

Most whole home water filter systems combine several media types, including carbon filter media, KDF media, and submicron sediment media. None of these media can remove minerals from a hard water supply.

Can a whole house filter remove hard water

πŸ€” What Is Hard Water?

A lot of people know that hard water is bad without actually knowing what it is.

Actually, drinking hard water isn’t bad, or dangerous, or unhealthy in any way. Hard water simply has a high mineral content. The calcium and magnesium minerals in hard water give it a pleasant taste and contribute to your daily mineral requirements.

So why do so many people want to get rid of water hardness?

Because it’s incredibly damaging to plumbing and appliances.

Hard water minerals deposit a white, chalky residue known as scale on pipes and water-using appliances. This scale buildup reduces water flow rate and appliance efficiency, even shortening the lifespans of your appliances.

Plus, hard water also leaves mineral deposits on your skin and hair, which may cause them to dry out.

Hard water causes limescale deposits and dry and itchy skin

What Qualifies As Hard Water?

Water with more than 7 GPG (grains per gallon) or 120 PPM (parts per million) of calcium or magnesium is classed as hard water.

If your water has more minerals than this, it’s classed as very hard or extremely hard.

HardnessGrains per Gallon (GPG)Parts per Million (PPM) & mg/L
Soft<1 0 – 17
Slightly Hard1.5 – 517 – 60
Moderately Hard3.5 – 7 60 – 120
Hard7 – 10120 – 180
Very Hard>10>180

You’ll probably know if you have hard water because you’ll notice scale around your faucets, in your coffee pot, and on your showerhead. You might also notice that your water doesn’t lather well with soap.

Hard water is safe, but it causes a lot of damage around the home. That’s why so many people are keen to eliminate water hardness – and why some people assume that, as a water quality issue, hard water can be remedied with whole home water filters.

How is Hard Water Measured

πŸ’β€β™‚οΈ Why Don’t Whole House Water Filters Soften Hard Water?

A whole house water filtration system can’t soften water because it isn’t designed to remove calcium and magnesium minerals from a water supply.

Most point of entry water filters use several stages of filtration to thoroughly remove a selection of contaminants from a whole home water supply.

The systems use filter media that either blocks contaminants from passing through (due to their small pore size) or uses a chemical reaction like adsorption or oxidation-reduction to pull contaminants out of water. Neither of these methods is typically effective at removing hard water minerals.

A filter might remove a small amount of water hardness, depending on its media type and pore size. But you can’t rely on a whole house water filter system to treat water hardness.

The only way to effectively tackle this problem is with a water softener.

Springwell SS ion exchange water softener tanks

The only exception is a whole house reverse osmosis system. RO systems have a semi-permeable membrane that contains tiny pores (usually 0.0001 microns), which are small enough to reject most total dissolved solids, including hard minerals.

❗️ If you have moderately hard to very hard water, we wouldn’t recommend using a reverse osmosis system to produce soft water. The hard minerals will damage the membrane and significantly reduce its lifespan.

🧫 What CAN A Whole House Water Filter Remove?

We know now that a whole house water filter can’t treat hard water or remove calcium and magnesium minerals – so what CAN this water treatment system remove?

There are several types of whole house water filters, and they don’t all filter water to produce the same results.

POE systems for city water use typically remove contaminants that are common in a municipal water supply, including:

  • Lead
  • Chlorine
  • Pesticides
  • Herbicides
  • Nitrates and nitrites
  • Some VOCs
  • Some disinfection byproducts
  • Heavy metals

Specialist filters can also remove fluoride, arsenic, and chloramine. Whole home water filters for well water may remove some or all of the following contaminants:

  • Sediment
  • Iron
  • Sulfur
  • Manganese
  • Other heavy metals
  • Nitrates and nitrites
  • Turbidity
  • Tannins
Water contaminants

The contaminants removed by a whole house water filtration system depend on the system type and the filter media involved.

If you want to go all-out and remove as many contaminants as possible, you could upgrade to a whole house reverse osmosis system, which removes up to 99.99% of all total dissolved solids in drinking water. Whole home RO systems are expensive, though, and often require pre-treatment.

Note that you don’t have this sort of flexibility with a water softener. No matter what type of water softener you buy, it’ll treat the same water quality issue every time.

Some water softeners can treat low iron levels, too, but for the most part, the majority of water softeners achieve the same end result. 

βœ… The Best Way To Soften Hard Water

The best whole house system to soften water is a water softener.

Like whole house filter systems, water softeners are installed as point of entry systems and are designed to treat the water supply in your entire home.

πŸ“Œ How are water softeners different from water filters? They’re designed with the sole intention of removing hard water ions and preventing mineral buildup.

While a water filtration system blocks or pulls contaminants out of water, a water softener uses a unique process called ion exchange to produce soft water.

During ion exchange, water flows through a tank containing charged resin beads, which are loaded with ions with an opposite charge (usually sodium). As water travels through the resin, the calcium and magnesium ions are attracted to, and stick to, the beads. This triggers the release of sodium ions into the water to balance out its charge.

water softening process

The outcome? All the calcium and magnesium ions are swapped with sodium ions, resulting in soft water.

As long as you set your water softener properly and use good salt, you can virtually eliminate all hardness minerals with a water softener.

πŸ†š Which Is Right For Me: A Water Softener or Whole House Water Filter?

Many people choose to install both soft water systems and water filter systems in their homes to tackle hard water and remove contaminants. Here are our favorite filter + softener combo systems if you want to learn more.

By the way, if you don’t like the sound of adding salt to your water, you can use a salt-free water conditioner instead of a water softener. Salt-free water conditioner systems use a natural, salt-free process called Template Assisted Crystallization (TAC) to crystallize hard water minerals, preventing them from sticking to surfaces as scale.

Whole home water filter vs water softener system


Can a whole house water filter help with hard water?

A whole house water filter might help with mildly hard water, depending on the media used in the system. However, if you have moderately hard to very hard water, the only way to properly address the problem is with a water softener system.

Does a whole house filter replace a water softener?

No, a whole house water filter doesn’t replace a water softener. Filters and water softeners have their own individual processes, purposes, and outcomes. Filtration systems filter water, while water softeners soften water. You can’t interchange a water filter and a water softener and expect the same results.

Does hard water damage a water filter?

Yes. If you have hard or very hard water, the minerals will leave scale deposits in the filter media, just as they do in your pipes and appliances. This scale will coat the filter media and clog the pores, preventing water particles from passing through. You might find that you have to replace your filter more frequently due to a reduced media lifespan as a result of treating hard water. The best way to prevent hard water damage to a filter is to install a water softener before the filter system.

Is there such thing as a hard water filter?

No, hard water filters don’t exist. If you read advice on the internet telling you to buy a water filter for hard water, it’s probably been written by someone who doesn’t know much about the water treatment industry and/or is actually referring to a water softener. The only exception is some shower filters, which have limited scale controlling abilities. But the best solution to hard water is a water softener.

  • Laura Shallcross
    Senior Editor

    Laura is a passionate residential water treatment journalist who holds an undergraduate degree in Print Journalism and a master’s degree in Creative Writing. Over a span of 5 years she's written on a range of topics including water softening, well water treatment, and purification processes.

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