Lifespan Of Activated Carbon Water Filters – Do They Really Expire?

Knowing how long activated carbon water filters last is important not only for the taste and to ensure it keeps removing contaminants – but also so you don’t go out and buy a replacement when you may not need to. So, to make it easy, we’ve put together a comprehensive guide on how long activated carbon actually lasts, what shortens its lifespan and what you can do to make some last a little longer.

Activated carbon water filters last between 2 and 6 months from first use. Some activated carbon filters are protected by other filters and can last up to 12 months, such as reverse osmosis or whole house systems. Poor quality tap water and frequent use reduces the lifespan of activated carbon.

Unfortunately, activated carbon filters won’t last forever and there are a number of things that will quickly shorten their lifespan. Keep reading and we’ll explain everything you need to know.

How long do activated carbon filters really last in water filters?

Most companies use some form of activated carbon (also known as activated charcoal) in their water filters, primarily to harmful contaminants, but also to remove bad odors and improve taste. Knowing exactly how long these filters actually last is crucial in maintaining their effectiveness and to keep you and your family safe.

Many companies will provide both the number of gallons and months of use the activated carbon filters should last, while others just provide one of these values. However, no matter how long these companies suggest their water filters should last, almost all will caveat these numbers by saying

“the filter life may vary based on local water conditions and how much you use it”.

In truth, they are absolutely correct! There is no EXACT time stamp that can be put on an activated carbon filter. The level of contaminants in your water will largely determine the lifespan of the carbon. And of course, the more you use the filter, the faster the activated carbon will be used up.

However, before we get into the details on how this all works, lets first check out some of the main brands that use activated carbon filters and how long they say they can be used for:

Activated carbon filters – For Reverse Osmosis (RO), Whole House & Under Sink Systems

Brand / Product GallonsMonths
Aquaboon – RO & Under sink
– Universal 10″ activated carbon
PurePlus – Whole house and RO
– 5 Micron 10″ x 4.5″ Big Blue sediment filter + activated carbon
13,000 3-6
Express Waters – RO & Under sink
– Universal 10″ activated carbon
Frizzlife – RO
– Stage 4: Granular activated carbon
Aquasana – Whole house
– OptimH20 catalytic and activated carbon filter (with LED indicator)
Aquasana – RO
OptimH20 Activated carbon & Claryum
Clear2o – Whole house
– CTO1102 Universal solid carbon water filter
Ronaqua – RO
– 10″ Activated carbon universal water filter
Pure T – Under sink / inline
– 10″ Inline granulated activated carbon filter

Activated carbon filters – For Pitchers

Brand / Product GallonsMonths
– Clean water machine (AQ-CWM)
– Powered water filtration system (AQ-PWFS)
– Standard water filter (White)
Epic Pure water filter pitcher
– Our TOP PICK for home use! – find more details in our post here
Epic Nano water filter pitcher
– We recommend this one for WELL WATER USERSread about it here

Activated carbon filters – For Faucets

Brand / ProductGallonsMonths
– Activated carbon filter
Water Drop
– 320 Gallon long-lasting water filter
– Advanced faucet water filter

Activated carbon filters – For Water Coolers

Brand / ProductGallonsMonths
Avalon Bottleless Water Cooler
– Stage 2: Activated carbon filter
Bluline G5 Global Water Cooler
– Stage 2: Activated carbon filter

So, one of the first things you may have noticed in the tables above is each activated carbon filer has a different number of gallons that they can process. In comparison, none of them last longer than 12 months, and MOST only last around 6 months.

So why is this the case?

Well, let’s take a closer look…

Lifespan based on number of months

All water filter systems have an expiry date, and it’s very important to follow the manufacturers specified replacement time frames for activated carbon filters. Even if the lifespan of a water filter is in both gallons and months, knowing when to replace it really comes down to

ONE of them expiring FIRST.

Activated carbon filters are excellent at removing contaminants from water. There are over 150 different types of manufactured activated carbon. Each one has been specifically designed and will have different properties, including:

  • Surface area
  • Pore size distribution
  • Catalytic properties (affects how certain contaminants are changed at the carbon surface)
  • Absorption
  • Adsorption (how contaminants adhere to the carbon)

Together, these properties are what sets activated carbon apart from other forms of filtration. They provide an incredibly high level of porosity and surface area, where surface chemical reactions and, MOST IMPORTANTLY, adsorption can take place.

I’ll discuss what ADSORPTION means in a lot more detail in just a minute.

At present, there is no convenient method for determining exactly how many months activated carbon will last as it can vary greatly between households.

For this reason, manufacturers take a slightly conservative approach when providing the expected lifespan in months. To be fair however, manufactures must consider how quickly (or slowly) activated carbon may age as a result of adsorbing impurities from various regions and at what point the level of contaminants in the filtered water will likely become unacceptable.

So, yes in theory, activated carbon COULD last longer than the recommended number of months stated, BUT it could just as easily last for less. As mentioned before, the lifespan of the activated carbon can dramatically change depending on your location, tap water quality and how much you use it.

With this in mind, the activated carbon filter material carries a recommended number of months before it should be replaced.

Knowing that your activated carbon is still reliably providing effective filtration is what’s most important. So, if your filter expires in 6 months then don’t use it for 8, even if you haven’t reached your “gallons quota” yet.

Lifespan based on number of gallons

Now, let’s take a closer look at the number of gallons you can use the activated carbon filter before replacement.

Activated carbon filters are designed to filter a certain amount of water. To understand why this is, first we have to understand the properties of activated carbon and what causes them to become “filled up”.

How does activated carbon work?

Surface area

Surface area is one of the key differences between regular carbon and activated carbon. Activated carbon is made by physical or chemical activation, which creates millions of micro-pores (tiny spaces) and “active” sites available for contaminant removal.

A large surface area means there is greater number of “active” sites on the carbon media that can interact with the unfiltered (tap) water.

The surface area of activated carbon is INSANE!

Just 10 grams of activated carbon has the same surface area as nearly 24 Olympic sized swimming pools!

Pore size distribution

Pore sizes and their relative distribution in the filter affects how the water moves in and around the carbon. In truth, getting the pore size distribution right can be a bit of a trade off between:

  • Desired filter speed (most people want it to run quickly)
  • Desired contaminant removal (most people want more of that too)

Generally, if there are large pores that are close together (badly distributed), more water and contaminants will preferentially flow through these areas, and not get removed from the water during filtration.

Catalytic properties

Activated carbon is often created as catalytic activated carbon, using a gas processing technique at high pressures. This enhances the removal of certain chemical contaminants from water such as:

  • Chloramine
  • Hydrogen sulfide

This catalytic functionality is often considered more advanced than traditional activated carbon and works by chemically changing (reacting with) a contaminant that enters the filter, which then comes out as an another. For example:

  • Chloramine converts to Chloride
  • Hydrogen sulfide converts to sulfuric and sulfurous acids

This added catalytic functionality is considered better than traditional activated carbon.


Absorption is all about how carbon soaks up the water. Absorption relates to how efficiently the contaminants move INTO the carbon, after which it can be adsorbed (adhered) onto the carbon surface.

The reason why absorption is so important in activated carbon relates to how quickly it can reach an expected filtering efficiency:

Fast absorption = fast and efficient filtration


Adsorption is basically what all the other properties listed above aim to enhance in the filter.

Adsorption is what is particularly important when it comes to how long the activated carbon will last and how many gallons it can process. It is this property in activated carbon that makes contaminants in water adhere (or stick) to the carbon surface.

What limits the number of gallons an activated carbon filter can process, and eventually “expire”, is how much it has adsorbed.

Once all the “active” sites have been used up, there is no longer any room for chemicals to adhere to the activated carbon, then the filters lifespan has unfortunately run out.

Much like a deactivated Dalek, an activated carbon filter becomes “deactivated” once its usefulness has ended. i.e. once it as adsorbed (taken up) all it can from the water.

The number of gallons of water an activated carbon filter can process depends on what’s in your water supply. Here’s some more detail on how this works.

What reduces the lifespan of activated carbon filters?

Let’s jump right into why the lifespan of activated carbon filters varies with differences in tap water quality.

Water quality

The number of gallons a water filter is recommended for is usually a “best case scenario” and the true length of time is probably a lot less.

Because the level of contaminants in tap water can vary greatly across the U.S. and even between households, the volume of water an activated carbon filter will actually last varies accordingly.

A contaminant is a broad term that applies to anything that is dissolved or suspended in the tap water. They can be both good, such as minerals, or bad, such as harmful chemicals or heavy metals.

Activated carbon takes up many of these contaminants, but higher levels in your tap water (or source water) will dramatically reduce the lifespan of the filter.

So, how many gallons do activated carbon filters last in the real world? Well, you may have already guessed, but the answer is… “it depends”.

…depending on your location, tap water quality and how much you use it.

So, the best tip we have is… find out about your local water:

  • Is it hard or soft water (does it have lots of minerals in it)?
  • Is it high in metals (e.g. lead, copper, mercury, aluminum, manganese)?
  • Is it chlorinated?

All of these will “use up” the active sites on your filter and reduce its lifespan – but don’t forget, this is what you WANT your filter to do!

Remove all the contaminants from your water!!

How to make activated carbon filters last a little longer

Here’s a few tips to make sure your activated carbon filters last just that little bit longer:

1. Clean your activated carbon filter (if you can)

Some activated carbon filters can be cleaned. This increases their lifespan by removing surface sediments and unblocking clogged pores. Here’s a few tips on how to clean them, without damaging the filter or yourself in the process:

  • Wear gloves – you are working with a concentrated form of chemicals, potential biological hazards and other contaminants.
  • Only use warm water, as hot water can damage some carbon (e.g. carbon blocks).
  • Use a paper towel to remove any surface scum from the plastic casings (inside, top and bottom). This will help remove any biological film.
  • Run the water filter for a good while before drinking any water to make sure you are not drinking any of the loosened contaminants.

2. Change your pre-filter and sediment filter regularly

Most whole house, under sink (some countertop) and reverse osmosis systems have a pre-filter and additional sediment filters before water reaches the activated carbon filter or block. These filters are generally much cheaper than the carbon filters and replacing them more often will increase the number of gallons and length of time your activated carbon filter will last.

An easy way to tell if your pre-filter or sediment filters are getting clogged up is if the water pressure in your tap or inline water pressure gauge starts to drop. Replace these filters asap if you notice the pressure start to drop.

3. Zip-lock your activated carbon filters when you go away

Activated carbon adsorbs impurities from water and also from the air. If you are going away for a while you can always put your drained activated carbon filters into a zip-lock bag to stop them soaking up any impurities from the air and make them last a little bit longer.

4. Don’t let them freeze

You may have an activated carbon filter block in your RV, camper or vacation home that could get exposed to freezing temperatures. If the water inside a carbon block freezes it can cause damaging micro-cracks, which then allow unfiltered water to pass straight through the next time you use it.

To avoid this from happening, you’ll need to winterize your filters. Simply drain all the water from the unit if you know you will you won’t be using it for a while.

How often should activated carbon filters be changed?

Activated carbon filters should always be changed once they have reached the lifespan advised by the manufacturer – whether it be a certain number of gallons or months. If you know your water is high in contaminants, ions, minerals or organic materials then your filter should probably be changed even earlier.

As we have discussed already – this will ensure your water filter is effectively cleaning your water!

Related questions

Is activated carbon a hazardous material?

Activated carbon is not a hazardous material or waste by itself. However, once the activated carbon has been used it can become hazardous waste because of the contaminants it has adsorbed.

Can you reactivate a used carbon filter?

Reactivating carbon is the process of removing organic compounds adsorbed onto the carbon, which restores the pore volume and surface area of the used carbon. To do it properly (and safely) it requires some specialized equipment, such as an inert gas chamber or steam furnace and temperatures in excess of 1,500 °F (850 °C).

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