Do I Need a Water Softener?

Do I Need A Water Softener If I Have A Whole House Filter?

If you are using a whole house filter, you might have asked yourself a couple of times: Do I need a water softener if I have a whole house filter? I will slightly tweak a question there. How do I know, I need a softener with your whole house filter? In this article, we will this out together.

Whole house water filters are not capable of softening water unless they come in a system with a softener. So, if you regularly notice limescale on your appliances, a water softener is definitely a smart investment. Before, invest into softener make sure to check the hardness of your water.

I will explain the difference between whole house filters and softeners, as these two systems have completely separate purpose. Also, we will have a look at what they can and can’t do and at the end, evaluate whether you need both or not.

Whole House Filter

Since you own a whole house filter, you probably know what the purpose of it is, but let’s make a short recap.

Typically, whole house filters have a couple of stages, but this might not necessarily be the rule. You can install the as simple system as one stage or go for a fancy unit with five stages.

For the sake of simplicity, let’s take an average system with three stages.

These usually have sediment filters and carbon block cartridges. Some filters have KDF cartridges, which is just a more advanced version of coconut carbon that prevents bacteria from inhibiting inside the filter.

The main purpose of whole house filters is to treat water and remove harmful contaminants from it.

What Whole House Filters Remove?

Now, systems are great at removing following contaminants:

  • Chlorine and Chloramine
  • Heavy Metals
  • Rust
  • Sediment
  • Arsenic
  • Lead
  • Iron
  • Pesticides
  • Other harmful substances

I have only included the most common contaminants that are typically present in water, but the list could be much longer.

Now, this being said, whole house units are doing a great job at filtering water, but what they cannot do is to soften it.

The issue is that cartridges used to treat water are not capable of removing minerals typically present in hard water.

These typically are:

  • Calcium
  • Magnesium

These are the minerals responsible for limescale on your appliances and other annoying things such as laundry, skin irritation etc.

The thing is that these minerals are smaller than cartridge pores, which allows them to pass the treatment process easily.

Let’s have a look on softeners.


There are two types of softeners: salt based and salt-free.

Salt-based softeners are real softeners in terms of softening water.

Let me explain.

Softeners that are using salt as softening medium, actually remove minerals of water. The principle is simple, softener resin replaces ions of earlier mentioned minerals with ions of sodium. Water after softener is soft and even sometimes we refer to it as silky.

On the other hand, salt-free units are not precisely softeners, even though companies often refer to them this way. The correct term for these would be conditioners. What they do is that they prevent minerals from adhering to appliances and create limescale.

However, they don’t remove these minerals from water, and they are not efficient with very hard water.

Can Water Softeners Filter Water?

Let’s talk about softeners ability to filter the water, and bust some myths around it.

I will make it clear from the beginning that salt-free softeners use certain pre-filter that will do some very very basic treatment. However, I don’t believe that this is enough to substitute a proper filter.

Now, salt-based softeners are capable of removing small levels of iron. Apart from that, the main purpose of the softener is to make water soft, and they are not a substitute for filters.

Difference Between Filters and Softeners

I am under the impression that you have got the idea about both systems and their purpose, but let me recap again.

Whole house filters will not soften your water, and their primary purpose is to make water free of contaminants. Although they might slightly reduce the occurrence of minerals in the water, the change is so small that you won’t notice the difference.

Similarly, softeners are designed to soften the water, and filtration is not their purpose. However, salt-based softeners are capable of removing a small amount of iron from water.

So, this is clear, but now the question occurs whether do you need both or not?

Do You Need Both?

Now, this section will be helpful for people who already have a whole house filter installed as well as people who are only planning to.

I believe that if you live in a house where well is the main source of water, you will almost always need both systems.

Let me explain:

Groundwater is usually not processed in any way, and chances are, that it’s going to be exposed to contaminants typical to the local environment.

This could involve all sorts of runoffs, including agricultural, industrial, or commercial.

These are getting into the ground and eventually end up in the water. For this reason, the whole house filter is a necessity for house owners.

The softener is also almost a necessity for people connected to the well.

The thing is, well water is naturally rich in minerals which is the cause of its hardness.

Hard water causes a lot of troubles, especially for your appliances, laundry, and skin. So, the softener is definitely a good solution which raises another question on which one to select?

Salt-Free vs Salt-Based

I have explained the difference between these two already.

But what is the most important thing for you to know is when to select these.

In short, salt-free softeners won’t be very efficient with very hard water. However, if you are looking to soften moderately soft water, this is a good option.

Salt-based softeners are a good option for very hard water.

I know what is running through your mind right now. What is moderately and very hard water? How could I determine it?

No worries about this as I got you covered.

The best way to determine the hardness of water is to use TDS meter.

TDS meters calculate total dissolved solids in water and will give you a number which is a measure of hardness.

To better understand the level of hardness, just check the table below I have created for you.

Milligrams per liter (mg/l) and parts per million (ppm)U.S. Geological Survey Classification
<17.1 soft
17.1 - 60 soft
60 - 120 moderately hard
120 - 180 hard
180> very hard


The bottom line is that you need to test your water to establish level of hardness.

Although if there is clear buildup, and you are replacing a washing machine every year, then it’s apparent that your water is hard and softener will benefit you.

I hope you have found everything you have been looking for in this article and you haven’t got any questions left. If you do though, don’t be afraid to reach out to me via comments below.

  • What whole house water filter do you currently use?
  • Which softener are you planning to use?

Share your insights in the comment section below.

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