Water Filtration vs Water Softener – Differences and Which to Use When

Author: Rory Mullan - Published: 2021/08/13 - Updated: 2022/11/08

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Due to the misinformation spread by some manufacturers, people are confused about the roles of water softeners and water filters. While it’s true that water filters remove contaminants from (drinking) water, the same cannot be said about softeners.

In fact, water softeners do little to nothing when it comes to filtering water. What they do is remove hard water minerals. The goal: Producing soft water.

Meanwhile, another common misconception is that water filters can soften water, removing said hardness minerals. Again, this is due to untrue claims and confusing language used by some companies.

Since this uncertainty can lead to you making the wrong buying decision, we explain the difference between both types of appliances and guide you on choosing the right option for your particular circumstances.

So, here is our guide on water softeners vs water filters!


  • Test the water in your home.
  • You are dealing with water hardness and need a softening system if you’ve found excessive calcium and other mineral levels.
  • Water softeners help you save money on maintenance and repairs by avoiding the buildup of limescale in your plumbing and home appliances.
  • A water filter is required if your water has an undesirable taste or odor, or if you are exposed to harmful impurities that should be eliminated.
  • Lead, arsenic, and PFOA are just a few of the toxins that can be effectively removed by water filters. If having potable water is your main priority, then these are perfect for you.

Water Filtration vs Softening: The Difference Between a Softener and a Whole House Filter

Water Softener vs Water Filter Thumbnail

Water softener vs water filter – to put it simply, water filters purify water. Depending on the type, they remove dirt particles, hazardous chemicals, heavy metals and more. On the other hand, water softeners primarily remove hard minerals, namely calcium and magnesium, from water, making it softer.

What is Hard Water?

First off, it’s important to understand why hard water is a problem. On a larger scope, hard water does not have any health effects. However, it can be a nuisance for your kitchen electronics, washing machine, dishwasher, your clothes, and even your hair and skin.[1]

That’s because hard water contains high levels of calcium and possibly other minerals. When left untreated, the minerals deposit as limescale buildup on surfaces of your entire plumbing system including water-using appliances. This can cause clogging which results in a drop in water pressure and flow, and could eventually lead to leakages and other costly maintenance and repair works.

Hard water also leaves ugly stains and spots on your shower head and door, on faucets and taps, toilets, sink – any kind of fixture basically. Plus, it can ruin your clothes making them rough and look faded. And on top of that some people’s hair and skin gets irritated when washed with hard water.

What Do Water Softeners Do?

Water softeners are merely aimed at softening water to prevent all the problems listed above; eliminating limescale buildup in pipes and appliances being the main focus. Water softeners do this in one of two ways:

  1. They apply a salt-based mechanism that entirely removes all traces of calcium from the water. The principle of ion exchange is at play here, replacing mineral ions with sodium ions.
  2. They work without the addition of salt and rather ‘condition’ water by altering the behavior of the mineral ions, lessening their tendency to stick or deposit on surfaces. The benefit of this method is the absence of excess sodium in the water, which is good for people with several health conditions. What’s more, salt-free water softeners don’t need to regenerate which saves a lot of water. But eliminating the scaling effects of hardness minerals this way doesn’t solve staining and neither does it benefit your hair, skin and laundry.

Both methods work, although the salt-based mechanism has the upper hand.

By the way, since water softeners are point-of-entry systems, they are installed at the main water line. As a result, they soften the water coming to every faucet in the house.

To summarize: Along with increasing the longevity of your plumbing, water softening also increases the lifespan of dishwashers, washing machines, and other appliances, such as your coffee machine, by removing hard minerals entirely or just their scaling effects.

Does a Water Softener Filter Water?

No, water softeners do not filter water. They only remove hard minerals. Some may also be suitable to remove low levels of ferrous iron, but that’s about it. Water softeners do not remove microorganisms, or heavy metals, or chemicals, or other contaminants from water.

What Do Water Filters Do?

Water filters are designed to remove contaminants from water and thus make it suited for one or more specific purposes.

  • This could be direct consumption through drinking which requires the water to be microbiologically-safe and free from other hazardous-to-health contaminants. Good taste and no unpleasant odor are other common criteria.
  • Or you might need a whole house water filter to rid your water from iron which leaves stains in your sinks and toilets and also damages your appliances.

two water filter cartridges dropped in water

The most common types of water filters include activated carbon filters, sediment filters, KDF filters and more specialized systems for removing certain heavy metals, sulfur, arsenic, or to neutralize acidic water.

All these water filter types may have a different working mechanism, but the end result is always the same – cleaner water.

And unlike water softeners, water filters can be installed pretty much anywhere. Sure, whole house water filters go on the main water supply line. But you can keep a point-of-use water filter on your countertop or install it under your sink. Some filters also attach to the faucet, making it easier for single-person households to have access to clean drinking water.

Does a Water Filter Soften Water?

Does a water filter soften water?

Let’s look at the question from a different angle. Do water filters remove hard minerals? The short answer is No.

Granted, some models may remove some particles of calcium and magnesium from hard water, but these bits will soon end up clogging the pores, rendering the filter useless for its primary functioning of cleansing water.

The bottom line is, water filters do not soften water, just like water softeners do not filter water.

Water Softener vs Water Filter – Which to Choose

Now, let’s come to the million-dollar question of which of the two you should choose for your home: A whole house water filter or a water softener? That depends on the following factors:

  • Water hardness
  • Water purity

If the water in your home contains a high amount of magnesium, calcium, and other hard minerals, you should opt for a softening system.

Meanwhile, if overall TDS, pesticides, lead, chromium[2], chlorine, arsenic, and other impurities are abundant in your water that you might even plan on drinking, you need to get a water filter for your home.

How to Identify Water Hardness?

Limescale can’t hide even if it tries to, so it will be easy for you to figure out you’re dealing with a hard water problem. You will notice scale deposits on your kitchen appliances, faucets, sinks, and tubs.

Moreover, even after passing through the dishwasher, your cutlery and dishes will have white spots on them. You’ll notice the same with your laundry. Clothes will start to lose their shine over time.

In this case, you must get a water softener, or you’ll end up paying a lot of money for appliance replacement and repair.

How to Identify Water Contamination?

different water filter stages

If there are harmful contaminants in your water, its taste and odor may give it away. Chlorine has a characteristic smell that will make it unbearable for you to drink the water directly from the faucet.

Likewise, some other contaminants are colored, so you will spot them easily in the water.

However, not all heavy metals and organics etc. affect water aesthetics. For example, this is the case for one of the most dangerous water contaminants there is: Lead. So, relying on your senses to identify underlying water contamination may not be a good idea.

Thus, the easiest and safest way to measure water purity reliably is to get your drinking water tested. Fortunately, you can get the reports for free as your local government has to provide you a quality report for the impurities found in your area’s water.

Alternatively, you can send a sample of water from your home to a local laboratory, and they’ll give you a report in a day or two.

Finally, there are some testing kits in the market that let you DIY the testing process. However, we won’t recommend this method since these tests are not always accurate and don’t test for all contaminants.

Do I Need a Water Softener if I Have a Whole House Water Filter and the Other Way Around?

Do you need a water softener if you already have a whole house water filter? And do you need a whole house water filter if you already own a water softener?

If your home gets unclean hard water, then you need to get both a water softener and a water filter.

In this case, here’s what we suggest. Install the water softener before the water filter. It will remove hardness from your water first. Then, the water will pass through the filter and get cleansed.

The main reason for installing the softener before the filter is to remove the sodium added during the softening process. A reverse osmosis filter can effectively remove almost all sodium from water, making it ready for drinking.

Also, calcium and magnesium are hard ions that can damage a reverse osmosis membrane. By softening the water prior to filtering, you increase the lifespan of the RO membrane.

If your water is chock-full of sand, rust or other dirt, though, we would suggest adding a pre-filter before the softener to trap any large sediment that may hinder the softening process or clog the softening system. Small sediment filters are really affordable and easy to install.

With this setup, you now have clean and soft water ready for use. It’s good for your health and appliances. It’s a win-win.


There is a misunderstanding about what water softeners do and what they can be used for. The same holds true for water filters.

A water softener removes hard water minerals and solves associated problems, first and foremost scaling.

A whole house water filter or POU system filters contaminants to make the water fit for a specific use, usually drinking.

Neither does a water softener free water from contaminants, nor does a water filter removes hardness minerals.

When you’re in doubt about which type of system you need, you should test your water quality. It’s also possible that you need both.

Further Reading


Meet Rory Mullan

Rory Mullan Rory has joined the Water Masterz team as a contributing writer. He has covered all sorts of topics in the last several years.

Outside of his writing work, Rory enjoys photographing the Irish landscape and making music!

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