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Home » Water Filtration Systems » How Do Whole House Water Filters Work?

How Do Whole House Water Filters Work?

By: Craig Smith
Last Updated:
How Do Whole House Water Filters Work

Even the clearest water that comes into your home will have at least some contaminants in it that may be undesirable to drink or detrimental to you and your family’s health.

This is the reason why so many people choose to install whole house filtration systems in their homes. That way 100% of the water that comes into their home will have many problematic impurities removed from it.

It’s a great way for you to be proactive as far as taking care of you and your family’s health along with eliminating some nuisance water-related problems too.

So exactly how do whole house water filters work? 

That’s what I will cover in greater detail in this article.

I will also talk about what a whole house filter is, the different types that are available, and some of the lesser-known benefits of having them in place on your incoming water line and working for you.

What Is a Whole House Water Filter?

There are two ways that you can choose when it comes to removing contaminants from the tap water that comes into your home. One is by removing impurities at your drinking water source. Aptly named point of use water filters.

The other way is to treat 100% of your incoming water supply immediately after the plumbing line enters your home. This is the purpose of a whole-house water filter and also why these are often called point of entry water filters (POE water filters).

Other common names for POE water filters are whole-home water filters and media filters.

Media filters are an appropriate name because whole home filters usually consist of a single big tank that contains several different types of filter media or a series of filter cartridges working in series that each has a specific type of filter media inside of them.

Those that have a POE water system that contains several filter canisters working in series will have to perform some periodic maintenance such as changing used-up filter elements. The benefit of these is that they will last a lifetime once put in place.

Single tank whole house filters contain several different types of filter media inside of them but for the most part, this filter media is not replaceable.

That makes them virtually maintenance-free but they have a lifespan of only 5 to 10 years depending on the purity of your incoming water.  

No matter which one you choose, these filters can significantly improve your home’s water quality. It does not matter whether you want to improve your water aesthetically (improve taste, smell, and color) or get rid of some concerning water contaminants, a whole house filter can definitely help with that.

How Does a Whole House Water Filter Work?


Since all point of entry water filters contain different types of filter media, they use a wide variety of ways to remove or reduce water contaminants.

This includes removing impurities from water by screening, filtration, micro-filtration (Adding a reverse osmosis stage), absorption, oxidation, ion exchange, or trapping.

Different types of filter media are used in whole house filters because there is no single best way to remove all of the different contaminants in your water that might be of concern to you.

Good reverse osmosis systems come closest but have trouble removing such harmful impurities as chlorine.   

So, by using multiple filter media types, whole home filters then can be used to eliminate such problematic water contaminants as Sulfur, iron, chlorine, pesticides, VOCs, and many more.

It must also be noted that not all whole home filter models work the same. Some will eliminate a large variety of contaminants while others may only target a few specific impurities.

This makes sense when you consider that everyone’s water quality is different and everyone has a different budget set aside as to what they can spend on a POE filter.

There is, however, one constant among media filters. You can count on them to have at least 3 different filtration segments. This goes for both filter canisters used in series and single tank point of entry filters.

I have seen whole house water filtration systems that contain 8 or more filtration stages or media types inside of them.

The different whole home water filter segments (stages) are as follows:

Sediment Pre-Filtration


These are extremely helpful for those that are having problems with silt, rust, sand, or other larger size particles getting into their water supply. You will probably appreciate this filtration segment the most if your home is supplied with well water.

Not only does this whole house filtration stage screen or block larger size water contaminants, but it also helps to keep the filter media in subsequent filtration segments cleaner.

This also increases the useful life of the media in the other filtration segments.  

Main Stage Water Treatment


This will generally consist of a combination of filtration segments that include 1 or more of the following:

  • Additional sediment filters
  • Carbon-based filters
  • KDF filter media
  • Specialized whole house water filters
  • Whole house reverse osmosis systems
  • And they may even contain such system add-ons as:
  • UV light filters
  • Water softeners
  • Water conditioners

It’s the filtration stage that does the most work when it comes to removing the bulk of the impurities in your tap water that concern you the most.

The above types of whole home filtration segments will all be discussed in more detail as you read this article.

A Post Filtration Stage

This is a small but important water filtration stage that will put the finishing enhancements on your incoming water supply. It does this by eliminating fine sediments and organic matter that may have been missed during the previous filter stages.

They also help to eliminate some of the byproducts that are created in other main treatment segments.

A good example of this is cleaning up the sodium chloride or potassium chloride that is left behind by salt-based water softeners after the ion exchange process takes place inside of them.

How Impactful Are Whole House Water Filters?

When these different filtration segments in point of entry water filters work in combination, they can be designed to effectively remove such water contaminants as silt, sand, lead, sulfur, chlorine, many microorganisms, pesticides, and more.

What Are the Different Types of Whole House Water Filters and What Do They Remove?

As was promised, here are some of the finer points of the different types of filtration media or water treatments mentioned above:

Sediment Pre-Filters

Some of the larger size contaminants in your tap water if not removed can do such things as clog pipes, use up the filter media quicker in other water filtration stages or devices (which can also hinder water pressure), and damage water heaters and other appliances.

That’s why it’s important to have a sediment prefilter that targets for removal dust, dirt, rust, metal particles, debris, silt, sand, and a variety of other larger-size water contaminants. They also can help eliminate water turbidity (cloudiness).

These come in all different micron sizes from as small as 1-micron (not often used in whole-house systems because of water pressure issues) to as large a pore size as 50-microns.

Sediment filters normally have to be replaced more often (usually every 3 to 6 months) than other types of filter segments.

Carbon-Based Whole House Water Filters

Sediment pre filters, while great at trapping or blocking larger size water impurities, allow many smaller size contaminants to pass through them.

That’s why you would be hard-pressed to find a whole house water filtration system that did not have at least one activated carbon filter stage in it.

These do a great job of eliminating smaller-sized contaminants and of absorbing the chlorine that’s used to treat many city water supplies. Some forms will also partially remove chlorine treatment byproducts (DBPs such as chloramines).

It’s also the most recommended type of water filtration media by the environmental protection agency (EPA) because it has the potential, depending on the type, to remove:

  • Up to 32 organic contaminants
  • Up to14 different pesticides
  • And12 concerning herbicides

The two most common types of carbon-based whole house water filters are the following:

  1. Granular Activated Carbon (GAC)

This effective point of entry water filter media contains granular activated carbon that is useful for catching finer sediment particles and for improving the aesthetic effects of drinking water such as the removal of chlorine taste, odor, color.  

They come in all different pore sizes but one that has at least a 20-micron pore size works best for this purpose.

  1. Catalytic Carbon (CTO)

This whole-home activated carbon filter stage contains what’s known as coconut shell carbon. One of its main advantages is it provides very good filtration and absorption without hindering water flow through the system.

It is one of the most impactful means of removing chloramines and also targets chlorine, many organic contaminants, pesticides, and chemicals for removal. These are usually found in a 5 to 10-micron pore size range.

It’s also worth noting that it’s not uncommon for both types carbon filter media to be used in the same POE water filtration system.

KDF Systems

KDF (Kinetic Degradation Fluxion) is known for being able to use oxidation/reduction (redox) to remove up to 95% of chlorine from drinking water along with such impurities as Lead, Nickel, Iron, Hydrogen sulfide, and some other heavy metals.

Due to its weight and high level of maintenance, it’s not used as a stand-alone POE filter media. It comes in two forms which are KDF-55 (used to treat city water) and KDF-85 (used for treating well water).

Whole House RO Water Filters

These types of water filters are known for removing even the smallest of water contaminants. They use a thin semi-permeable membrane (usually around 1-micron in size) that does not allow many water contaminants to pass through it.

This includes heavy metals, microorganisms, salts, and metalloids. It can be part of a POE system that produces very safe drinking water. Its biggest drawback is that it can create water pressure issues if a booster pump is not installed on the system.

Ultraviolet Light Systems


Here is a very useful POE water filtration system add-on that is very impactful when it comes to eliminating bacteria, fungi, viruses, parasites, and algae from tap water. Best of all they use no chemicals to work their magic.

The UV light rays simply alter the DNA of these microorganisms to render them ineffective at causing health issues.

Water Softeners

SpringWell Salt Based Water Softener

To be frank these are not used as stand-alone whole house water filters but can be very useful add-ons to them for those that suffer from hard water problems. Water softeners can eliminate scale buildup on bathroom fixtures and other hard water problems.

They work using a process called ion exchange. A salt solution with positive sodium ions coats special resin beads and when hard water minerals such as calcium or magnesium enter into the system their stronger positive charge causes them to displace the sodium ions and get captured.

Water Conditioners

Many people call these ‘water softeners’ but they work much differently than more traditional salt-based water softeners. They do not actually remove hard water minerals such as calcium and magnesium.

That’s because they use other means such as Template Assisted Crystallization (TAC) and electromagnetic waves to alter hard water minerals to help keep them from causing bothersome limescale.

Other Whole House Filter Benefits

You know that a proper working POE water filtration system will do a good job of removing some of the most problematic impurities that are found in your drinking water.

This is something that will significantly contribute to you and your family’s good health over a long period.  

That is the most important benefit that you get from having a whole home filter but certainly not the only one. Here are some of the others: 

  • They can be made to target specific worrisome contaminants
  • These systems can be found in many different budget ranges
  • DIY installation is possible with some of them
  • They can be bought to treat specific types of water (city or well water)
  • Whole house water filters can protect your skin and hair from damaging conditions
  • They can extend the useful life of water heaters and other appliances
  • POE water filters can prevent plumbing problems such as clogs and scale formation
  • Environmental gains can be had by using less bottled water

There is a Reason Whole House Filters are So Popular

If you have hard water concerns, unpleasant chlorine taste or odor, or a history of having other harmful impurities in your drinking water (best determined by home water testing), then you should strongly consider purchasing a POE water filtration system.

They will not only help keep your family healthier but will also eliminate some other nuisance problems around your home that are associated with water impurities.

I have one at my home and it makes me much more comfortable knowing that my family and I are drinking water that is much purer than when it first entered our home.

You can get help finding the right whole home filter for your needs by referring to our handy whole house water filter reviews guide.

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Craig Smith
Craig got his start in water working in the swimming pool and spa industry. Water treatment would grow into his main career but he ended up working in the pool industry for over 26 years where much of his time was spent balancing the water in customer's swimming pools and installing water filtration equipment. Craig offers an abundance of water treatment knowledge after helping homeowners get pure water for 26 years.

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