What is a Whole House Water Filter? How Do Whole House Water Filters Work?

Author: Rory Mullan - Published: 2021/09/02 - Updated: 2023/01/05

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Water filtration is a complex process of removing or reducing unwanted contaminants from your water. If you are here, you must be eager to find out how water filtration systems operate and if they work as claimed.

Well, there’s good news! A solid whole house water filter will make your water fresh, pure, and wholesome. This brings us to the question, do you need one and which type should you buy? This article will go over how numerous whole house water filters work, what they can remove, and help you analyze whether you should better get one for your household.

So, here is our guide answering the questions, what is a whole house water filter and how does a whole house water filter work?


  • A water filtration system that is installed near where the main water line enters your home is called a whole house water filter.  It’s a system that guarantees filtered water is delivered to every water outlet and appliance that uses water in your home.
  • Whole house water filters can be used to get rid of a variety of impurities and harmful toxins, including sediment, chlorine, PFOA, pesticides, iron, and manganese.

What is a Water Filtration System?

Whole house water filtration systems are point-of-entry units installed right where the water enters your home. So every drop that circulates around your plumbing is free of contaminant matter ideally.

As opposed to point-of-use filters, a whole house water filter provides clean and safe water for cooking, showering, cleaning, laundry, and dishes, not just drinking.

Since each household has a unique water quality, each requires a certain form of filtration system. Thankfully, there are over ten types of whole house water filters – each utilizing different technologies to achieve different levels of filtration.

They are designed to remove over hundreds of contaminants including sediment, sand, silt, chlorine/chloramine, heavy metals, industrial run-offs[1], pesticides and other chemicals, and salts.

Some of the pollutants are visible, while others are silent swimmers. Unfortunately, they are all unwelcome guests that lurk right under your nose, causing irreversible damage to your plumbing and health.

How Does a Whole House Water Filter Work?

What is a Whole House Water Filter and How Does it Work Thumbnail

Whole house water filters use one or multiple media to remove, block, reject, trap, damage, absorb, and adsorb numerous unwanted pollutants from your water.

Some employ mechanical filtration, while others use resin beds, e.g. activated carbon, or UV light to prevent the contaminants from entering your plumbing. Advanced water filtering systems feature multiple levels of filtration stages, removing even the tiniest microscopic contaminant from your water.

It is essential to know how whole house water filters work so you can select the best one according to your budget, water quality, and lifestyle. For instance, if your tap water is ridden with sand and large particles, a whole house sediment filter is all you need. On the other hand, if you are tired of smelly chlorinated water, a carbon-based filtration system is your best bet.

Here we explain the three most important stages of water filtration and how each is important to bring you pristine, safe water.


Pre-filters play an integral part in most whole house water filter systems. In fact, some filtration units may have more than one layer of pre-filter to effectively remove larger particles and make the water suitable for subsequent treatments.

As water moves through a sediment pre-filter, it traps dirt, sand, rust and debris – any large particle basically. A carbon pre-filter is effective at removing chlorine and larger dissolved solids.

Pre-filtration plays two critical roles in the whole treatment process.

  • First, pre-filters protect the primary media from harm or degradation. Some filtration media lose their capacity to treat water quickly if exposed to chlorine for example. Similarly, all main filter media are prone to clogging more often if exposed to water with larger contaminants. In simple terms, pre-filtration elongates the life of the primary filter.
  • The second reason for pre-filtration is to remove those contaminants that the main filter is unable to restrict. They act as a helping hand, and together, both pre-treatment and main filtration can filter far more effectively than only one stage.

Main Filtration

The most comprehensive stage of water purification is the main/primary treatment stage. This stage is specialized to target the specific contaminants you want to remove from your water. Here are some types of filters that you can select depending on the unique chemistry of your water.

  • Sediment filters
  • Carbon filters
  • KDF filters
  • Reverse osmosis systems
  • Iron filters
  • Ultraviolet light filters
  • Water softeners

Don’t get confused, as we shall dive into the details of all these types below. As for now, just remember you don’t need to say “I do” to dirty water anymore. There is a water filter for just about everything to set you free.


The post-filter is considered a polishing agent that gives the final touch to your water. It makes sure any remaining sediment or organic particles are eliminated before the water runs down your taps.

It will treat remaining odors, tastes, and textures from your water, so it is good to drink. In layman terms, it gives an airbrushed effect to your water, so it’s not just a variation of H2O but wholesome and pure.

Since each filtration method has its strengths and limitations on what it can remove, most whole house water filters use a combination of different techniques to achieve the desired level of purity. To give you another example, some water filters feature a post remineralization filter to add essential minerals back to the water.

Since the water that enters post-filters is mostly clean, they last longer than pre-filters.

The Different Types of Whole House Water Filters and What They Remove

Whole house water filters are available in different technologies, sizes, and styles. The two basic styles found in whole house filtration systems are:

  1. Tank based
  2. Cartridge based

Tank-based systems offer the longest filter life, negligible pressure drop, and applications for both city and well water. They do, however, require more space, electric power (most of the time), and mostly a drain to backwash the contaminants.

In contrast, cartridge-based whole house water filters are easier to install and maintain, plus require low house water pressure to operate. The catch: potential drop in water pressure and frequent filter replacements.

collection of whole house water filters

Now, let’s get down to the types of water filters. But first, it’s a good idea to know what exactly is the problem with your water supply. Is it laden with big undissolved particles or chock full of minerals? Is it highly chlorinated, or are bacteria or cysts your major concern?

We highly suggest not to play the guessing game and conduct a water test yourself. You can even ask your municipal board for a water report or send a sample to a laboratory to get an official result.

Once you have the complete picture, you can move onto the types of whole house water filters available in the market.

Sediment Filters

Sediment filters are mechanical filters that are based on the idea of physically removing sediment or dirt using a barrier. They can be either in the form of a basic mesh (sieve-like) that rejects the bigger contaminants or a depth filter that offers ultra-fine filtration owing to an intricate pore structure.

Sediment filters are given a micron rating depending on their filtration capacity. The micron size refers to the pore size of any given filter and highlights the filter’s effectiveness in terms of the size of particles it can reject.

The smaller the micron size, the more efficient the filtration is. For most sediment filters, the micron ratings vary from 0.5 microns to 50 microns. For reference, human hair is 70 microns in size.

Due to their design structure, sediment filters require frequent replacements. They may last anywhere between 3 to 6 months, depending on your water quality and daily usage.

Whole House Water Filters Using Carbon

Carbon-based filters are also among the most popular choices for residential whole house water filters. They are economical and effectively remove a wide range of contaminants to make water safe for usage.

They are perfectly suited to remove organic contaminants and chemicals – think pesticides – and water disinfectants, first and foremost chlorine.

There are two types of carbon filters: granular activated carbon (GAC) and activated carbon blocks. Both use either burned wood or coconut shell and have a huge internal surface to trap chemical impurities.

Catalytic Carbon

Catalytic carbon filters are more effective at removing chloramines compared to standard activated carbon filters. Chloramines are more stable and therefore are now widely used instead of chlorine to disinfect water.

Whole House Reverse Osmosis Water Filtration Systems

If you have been reading about water filters, the name reverse osmosis must have indeed caught your eye. RO systems are top-rated filtering units, thanks to their most thorough purification.

A whole house RO filter system can remove nitrates and other salts, heavy metals, bacteria, viruses, arsenic, sulfates, protozoa and so much more. But RO systems also remove the healthy and essential minerals from your water. Plus, they produce waste.

KDF Water Filters

KDF, Kinetic Degradation Fluxion, uses copper and zinc granules to remove:

  • Lead
  • Nickel
  • Iron
  • Hydrogen sulfide
  • And chlorine among other water contaminants.

However, this media is not very popular since it’s difficult to maintain. KDF is usually used in conjunction with activated carbon since it helps prolong the life of carbon filters.

UV Filters

Ultraviolet (UV) systems use UV light to alter the DNA of living organisms in water. When your water passes through a UV light filter, it eliminates bacteria, viruses, parasites, fungi, and algae.[2]

However, UV filters are not suitable to remove any other contaminants. Besides, they only work on water that is visibly clean. Due to their limitations, UV filters usually act as post-filters in whole house water filtration systems.

Whole House Water Filters Targeting Specific Contaminants

Specialized whole house water filters are used to target one or more specific contaminant. For example, an iron removal filter is popular for removing ferrous and ferric iron only.

Specialized water filters feature advanced technologies depending on the type of contaminant to remove.

Water Softeners

water softeners and whole house water filters

Water softeners are not usually huddled around as water filters since they don’t remove any contaminants. They are purifiers that remove mineral ions such as calcium and magnesium.

As water passes through the resin bed in a water softener, hardness-causing minerals are replaced with sodium ions through a process called ion exchange.

Whole House Water Filter Benefits

Most people are completely unaware of the perils of dirty water. They incorrectly assume that all tap water is perfectly treated at the source and requires no further filtration – not to speak about well water.

They fail to consider the challenges of water filtration at scale and also that their water has to cover a long journey through pipelines around the city. The water that reaches your taps may not be the same as it left the source.

Bottom line: the biggest advantage of whole house water filters is the peace of mind they bring to you. Pure water 24/7 all around the house is surely worth it.

In comparison, point of use water filtration, usually associated only with drinking water, treats only 1% of the total daily water consumed. However, unwanted contaminants pose a great risk to your appliances, plumbing, clothes, and yourself too.

Do You Need a Whole House Water Filter?

Are you tired of foul-smelling water that is given you a headache, literally? Or are you exhausted from the never-ending repairs to your appliances and plumbing due to sediment buildup?

Did you just nod at least once? If yes, you answered the query yourself and you need a whole house water filter. With that said, not all households are exemplary candidates for whole house water filter systems. If you are amongst those lucky ones where your water smells and tastes just fine or the plumbing never rusts, you are better off with a countertop filter for your kitchen sink or even water pitchers with filters.

In contrast, if you are experiencing turbidity, foul smells, scale buildup, and stained clothes, we suggest looking into whole house filters to make your water fit for residential usage.


In conclusion, whole house water filters are systems that filter all water as it enters a home.

Often, these filters make use of pre-treatment and post-treatment in addition to the main filtration process.

The most common whole house water filter types are sediment, carbon, reverse osmosis, KDF, UV and iron.

The main benefit of filtering water at the point of entry is that you have clean water everywhere which benefits your family and your plumbing + household appliances.

You most likely need one if your water has quality issues.

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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