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Water Filtration vs. Water Softening – Differences and What to Use When


Some people falsely believe that the water softening system they’ve installed in their home will protect them from harmful contaminants that might be present in their tap water. Truth is, water softeners have virtually zero effect on water quality in terms of purity. Other people are convinced that a water filter makes a great choice for treating hard water issues. Wrong again.

As there seems to be a lot of confusion about when to apply a water softener and when a water filter, we are going to point out what the differences between them are, and explain under what conditions one is better suited that the other.

On this page you will learn:

What’s the Difference Between a Water Filter and a Water Softener?

What Does a Water Filter Remove From Water?

A water filter is a system designed to remove contaminants or impurities from water, like heavy metals (lead, copper, cadmium, mercury), pesticides (herbicide, insecticides), dirt, and sediment. The reason why water utilities and individuals try to remove these substances is because they can make water taste and/or smell unpleasant, and they can also pose a threat to the health of everybody that gets in contact with them be it through direct consumption (drinking and cooking) or skin contact (showering).

The group of water filters includes mainly reverse osmosis (RO) systems, activated carbon filters, and microporous filters. Depending on which type is used, contaminants are either trapped in a system and then removed by cleansing or filter cartridge replacement, or they get flushed down the drain straight away.

Water Filter Removal Chart

Calcium Yes, RO (might damage membrane)
Magnesium Yes, RO (might damage membrane)
Sodium Yes, RO
Chlorine Yes, carbon filter (learn more)
Fluoride Yes, RO → learn more about fluoride removal
Iron Yes, RO
Lead Yes, RO & Some Carbon Filters → learn more

What Are You Waiting For? Find Our Reviews For the Best Reverse Osmosis Water Filter Systems Here!

What Does a Water Softener Remove From Water?

When softening water, the primary goal is not to remove certain contaminants as hard water does not pose a health risk. Quite the contrary, its mineral content is healthy for your body. Rather the purpose of a water softener is to prevent the build-up of limescale, and ultimately increase the lifespan of your house’s plumbing system, dishwasher, washing machine, and all other household appliances that use water. This goes especially for your water heater, which cannot work efficiently, when pipes are clogged.

Water softening can either happen by removing calcium and magnesium ions (hardness minerals), or by altering the behavior of these ions to reduce their affinity to attach themselves to surfaces. If the latter is the case, we also talk about ‘water conditioning’.

Softeners that remove hardness minerals from water are salt-based systems, which add either sodium or potassium to the water they treat. Regarding water conditioners or ‘salt-free softeners’, there are different types available; some apply magnetism, others are based on chelation, where the hardness minerals are bound to a chelating agent and as a result get suspended in the water.

Water Softener Removal Chart

Calcium Yes
Magnesium Yes
Sodium No, even adds more
Chlorine No
Fluoride No
Iron Only ferrous iron → learn more
Lead No

On a side note, if you are looking for a water softener to solve your hard-water problems, we provide many detailed water softener system reviews on this site. Simply follow this link:

Should You Install a Water Softener OR Water Filter in Your Home?

Deciding on a water filter or softener should depend on the current condition of your water. On the one hand, if there is a lot of calcium and magnesium dissolved in it and your household appliances start to build up scale, you are obviously dealing with hard water and a softening system is probably the best solution.

On the other hand, especially if you use your tap water for drinking and it has a strange taste to it or smells odd, it’s likely that it contains too many contaminants, which better be removed. In this case, a filter system is the right choice.

A Water Softener Protects Your Possessions, a Water Filter Protects Your Health.

How about addressing the problem from a different angle? Think about whether you want to use water from a specific water line for drinking and cooking, or not. If you are planning on drinking the water, it’s always better to install a proper filter unit, like an RO system. If the water is only used for example to do the laundry, install a softener.

Only a Test Can Give Reliable Insights


If you live in an urban area, the tap water you receive is likely to contain high amounts of chlorine. It’s a very common contaminant that both alters the taste and smell of water. Chlorination is used by water utilities to kill waterborne pathogens, which is a good thing. The bad thing though is that once the chlorine has dissolved into the water, it is very difficult to get back out.

For all you people from the countryside, this sounds like good news. You receive your water from a well and chlorine levels are presumably low. However, you should not underestimate the impact our agriculture has on groundwater

To boil it down, over 200 contaminants could be present in your tap water right now. The majority of them is highly dangerous and cannot be perceived with our eyes, nose or mouth. That’s why only a test conducted by an independent lab can provide reliable insights into the current status of your water.

Luckily, you don’t have to commission this test yourself. In fact, somebody already did that for you – for free! Almost every water utility in the United States has to annually provide a water quality report listing all the contaminants that were found in their water the previous year. All you have to do now is find out where you receive your water from and request a copy of the report.

tractor spraying pesticides


There are marks that hard water leaves in your home, such as stains on glasses and cutlery. But only by directly testing your water for hardness grains can you be certain about the level of hardness you are facing. You can get more info on how to test your water for hardness following this link:

Filtering Softened Water and Removing Sodium

If you struggle with hard water and also impurities that you wished would disappear, you have the option to use both a water softener plus a filter system. By the way, this is also our recommended order to set up the devices. First you have your softener that removes calcium and magnesium from water. Then you have for example a reverse osmosis filter system that removes up to 99 percent off all impurities including the sodium added in the softening process, which many consumers are concerned about anyway.

Through the use of a softener, you can also extend the lifespan of the RO membrane at the heart of the filter system. You have to know that these membranes are fragile and when facing very hard water, they tend to foul. As you can see, using a combination of a water softener and a water filter is a win-win situation!

You don’t have the money to buy a softening plus a filtering system? No problem! There is always the option to rent a water softener, which you can learn more about here.

Reverse Osmosis for Hard Water

Like we said, very hard water that contains high amounts of calcium and magnesium may cause a reverse osmosis membrane to start fouling. Therefore, the preferred method should always be to soften water first and let it run through an RO system subsequently.

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If you have any questions or thoughts about water filters, water softeners or similarities and differences between the two, please don’t hesitate to leave a comment below!

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