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Home » Water Filtration Systems » Whole House Water Filter Cartridge Types & Sizes

Whole House Water Filter Cartridge Types & Sizes

By: Craig Smith
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Whole House Water Filter Cartridge Types & Sizes

If you are looking to purchase a new whole house water filter or maybe upgrade your existing one, then you will need to know a little bit more about how the different filtration stages on these systems work.  

That information includes the different types and sizes of filter cartridges that are available for them. It’s a list that’s length will probably surprise you.

This is because whole house water filters need to have the ability to reduce or remove a wide variety of impurities that are commonly found in household water.

That’s why you must purchase or build a whole house filtration system with the right types of filter cartridges to make a significant impact on your home’s water quality.  

Here I will use my 26-years of water filtration experience to teach you much of the basic information that you will want to know about whole house water filter cartridge types and sizes.  

Helpful Resource: How to Choose a Whole House Filter: Complete Guide

Micron Ratings


One term that you will have to become familiar with when shopping for a new point of entry filter system is the term ‘micron rating’. This has to do with the pore size of the media that’s found inside a filter cartridge.

More specifically it’s about not allowing certain size water contaminants to pass through it.

This is something that varies greatly between different filter cartridge designs and types. 

For instance, a reverse osmosis system membrane may have a pore size as small as 1-micron while some sediment cartridges only can filter out impurities that are 50-microns or more.

Filter cartridge manufacturers must provide micron ratings for their products because it’s essential to know these ratings to determine what impurities a whole water filtration system can and can’t remove.

To complicate things even more there are two types of micron ratings that are associated with filter cartridges. There is a pretty substantial difference between these ratings as it applies to filter cartridges so you better know what these are.

1. Nominal Rated Filter Cartridges

These are filter cartridges that are known to screen out around 80% of the contaminants that are of a particular micron size or larger. You have to be very wary of nominal-rated filters when you are trying to filter out such dangerous water impurities as bacteria and other microorganisms.

Nominally rated filters are better used to remove particular-sized contaminants such as salts and hard water minerals which have less potential impact on your health.

Another problem with nominal rated filter cartridges is that there is no set standard for their efficiency.

Some manufacturers hold to the 80% contaminant removal standard while others may make their filter cartridges only 75% effective at removing the impurities that are a certain micron size or larger.

2. Absolute Rated Filter Cartridges

These are the much more reliable of the two main types of filter cartridge ratings. That’s because they will filter out 100% of the water impurities that pass through them that are equal to or greater than the micron size of their filter media.

I would recommend that if you make a DIY whole house water filter that you only build it using absolute rated filter cartridges. 

Physical Whole House Water Filter Cartridge Types

Whole house water filters (also called point of entry (POE), media, and whole home water filters) usually consist of several different filter stages. These stages often include a variety of cartridge types and sizes.

There are two types of whole house water filters that you can purchase. The first is media filters that consist of single tanks that include several different types of filter media stages inside of them.


The other type is a whole home water filtration system that consists of independent filter stages working in sequence with each other. Most often this is done by combining several different types of filter cartridges to make an effective water treatment system.


This is also why these are the types of point of entry filters that we will be discussing here in this article and their associated filter cartridges. 

Here are some of the various types of filter cartridges that make up these systems :

Sediment Filters


One of the most common types of filter cartridges that you will find in a point of entry water filter are sediment filters. They work using such effective water purification means as absorption and screening.

The biggest drawback with them is that they are very ineffective when it comes to reducing or removing microorganisms, heavy metals, salts, chlorine, and chemicals. 

That’s why they are most often used as prefilters.

Here are the three main types of sediment water filter cartridges explained:

1. Surface filters

The first line of defense for any water filtration system is its ability to filter out solids and large particles. That’s the job of surface filters and why they are often the first type of filter cartridge that is found in any whole house filter system.

They use pleats and other internal means to remove large particles and are often made so they can be easily cleaned and replaced.

2. Depth filter cartridges

While depth filters target the same large contaminants in tap water that surface filters do, they do it by a different means.

Most notably with string wound or melt-blown inner workings that are made of such durable materials as polypropylene, ceramic particles, cotton and glass fibers, cellulose, and polyester.

They also trap large contaminants as opposed to screening them and they are more often made to be replaced instead of cleaned.

3. Absorptive filters

These types of sediment filters can be made using the same means as any of the above-mentioned sediment filters but have inner media that absorbs water impurities.

They are more expensive than other sediment filters but offer smaller micron-sized filtration (as low as 2-microns) and use electrokinetic absorption to eliminate such concerning water contaminants as some microorganisms.

Reverse Osmosis


This is by far one of the most popular means of water purification because of its ability to eliminate water impurities that are as small as 1/1000th of a micron in size.

That means their small pore-sized membranes can remove up to 99.9% of some of the most worrisome water contaminants. These include tannins, bacteria, pesticides, nitrates, VOCs, heavy metals, and more.

Reverse osmosis filters are not always used on whole-home filter systems because they require a high amount of water pressure to work and this causes flow problems in the system.

Ultrafiltration Cartridges   

Here is another fine particle filtering physical whole house water filter cartridge type. They can be made to filter particles that are as small as .01 microns in size.

That makes them effective for removing such microorganisms as viruses, bacteria, proteins, colloids, parasites, pyrogens along with common herbicides and pesticides.

Much like reverse osmosis, these are used sparingly in POE water filters because they can significantly slow water flow rates in a home.

Common Chemical Whole House Filter Cartridge Types

There is a reason that physical and chemical cartridge filters are often both found working together inside whole house water filters. That’s because what impurities one type of cartridge does not remove well, the other usually does.

Such is the case with chemical filters because, unlike physical filters, they are very effective when it comes to removing undesirable dissolved particles, pollutants, and chemicals from water.

That makes them very useful for removing substances from your tap water such as chlorine, fluoride, nitrates, and pharmaceuticals.

Here are the most popular types of chemical filter cartridges and a brief description of how they work: 

Granular Activated Carbon Filter Cartridges (GAC)


There is a reason why GAC filter cartridges are commonly found in point-of-entry water filters. That’s because they are extremely porous and have a high amount of surface area.

This means they can absorb many types of impurities that are found in your water without significantly impacting the water pressure in your home.

They are extremely impactful when it comes to removing PFOS, pharmaceuticals, phosphates, chlorine, chlorine byproducts, pesticides, herbicides, and more.

Carbon Block Filters

Carbon block filters provide another very powerful carbon-based form of water purification that has one significant drawback. It’s that the type of carbon in them is much more closely packed than GAC style filter cartridges.

This increases filtration power but also often results in the loss of water pressure at the same time. Especially when these filters are used in smaller micron sizes such as 1 to 5-microns.

In smaller micron sizes they do have the ability to eliminate some microorganisms, lead, cryptosporidium, and giardia. These also can greatly enhance water aesthetics (such as eliminating chlorine taste, smell, and tinting).

Catalytic Carbon Filter Cartridges (CTO)


Over the years many city water suppliers have turned from using chlorine as a disinfectant to using a less expensive chlorine alternative that is mixed ammonia.

These are called ‘chloramines’ and standard activated carbon filters have trouble removing them. They also have trouble removing some of the disinfection byproducts (DBPs) that are created when chloramines react with organic compounds.

 CTO Filter Cartridges were created because their coconut shell carbon can remove chloramines, hydrogen sulfide, and other DBPs.

Ion Exchange Filter Cartridges

Not all contaminants in water can be absorbed, screened out, or filtered effectively. That’s where ion exchange filter cartridges have a role to play. They trap contaminants by using media that attracts the charged ions of impurities.

These filters are most effective at removing inorganic compounds such as arsenic and sulfides.

KDF Filter Cartridges

KDF cartridges are filter cartridges that remove such water impurities as chlorine, lead, and mercury using what’s known as oxidation and reduction (redox). They come in two types; KDF-55 for city water and KDF-85 for well water users.

They also help keep algae, fungi, and bacteria from growing inside a filtration system.

Specialty Filter Cartridges

These types of filter cartridges are often used by those that have a well water supply. Most often they are made to tackle situations where high levels of iron, lead, or sulfur are found in a water supply.

Iron filters and the others mentioned above can remove some other water impurities as well.  

Activated Alumina

Just as catalytic carbon filter cartridges were designed to remove stubborn chloramines, so too were activated alumina filter cartridges manufactured to eliminate fluoride. A popular additive that is used in many municipal water supplies.

These also help eliminate total dissolved solids (TDS) levels and arsenic from tap water.

UV Filters


While UV filters are not really classified as filter cartridges in the traditional sense, nonetheless, their encapsulated UV (ultraviolet) light chambers that water passes through treat water quickly and effectively.

They work by changing the DNA of living organisms such as bacteria and viruses (think problematic E. coli) to render them harmless. 

This and other whole house water filter add-ons such as water softeners can significantly improve the quality of your household water.

Whole House Water Filter Cartridge Sizes

There is no such thing as a standardized whole home water filter cartridge size. Much is up to each manufacturer and what they feel is best to get you the best water filtration results.

Common sizes include:

  • 2.5 x 10 inches
  • 2.5 x 20 inches
  • 4.5 x 10 inches
  • 4.5 x 20 inches

Some of the factors that manufacturers consider when deciding which filter cartridge types to include in their systems include their service life and the amount of maintenance involved in maintaining that type of filter. 

The flow rate through them also must be considered for several of the physical whole home filter types mentioned above. That’s because the smaller the micron rating, the more that filter cartridge will impact your home’s water pressure.

 This is why I often recommend to those that ask for my opinion on whole house water filters to find a decent working one to treat all of the water in their home and add a point of use filter (countertop, water pitcher, or under-sink filter) to further purify their drinking water.    

Which Type of Filter Cartridge Is Best for Your Water Problem?

This is a question that I cannot begin to answer for you unless I know what types of impurities are found in your tap water.

That’s why the best way to go about determining what types of filter cartridges you need to have in your whole house water filtration system should be determined by extensive home water testing.   

The best way to go about doing this is to order a water test kit online that uses professional laboratory analysis to determine what problematic impurities are found in your home’s water.


I recommend a test kit made by a company called ‘Tap Score’. Test kits like theirs are very effective and easy to use. 

You simply order them online, fill the water sample vials up when the test kit arrives, and then send those samples back to the company in a prepaid envelope for testing.

A few days later you will get an email with a detailed list of the contaminants that are present in your home’s water.

You will then be able to buy or make a whole house water filtration system that will reduce or remove the impurities in your water that concern you the most.

I also recommend that you check out our best whole house filter cartridge guide and best whole house filters article. This will help you purchase a POE filtration system that you will be extremely satisfied with for years to come. 

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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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