How Long Do Water Filters Last & How Often Should They Be Changed?

Considering investing in a water filter, and wondering exactly how much use you’ll get out of the filter before it calls it quits? Wondering whether water filters are worth the money? Keen to figure out when your existing water filter needs to be replaced?

You’ll find all the information you need to know about the average lifespans of water filters in this guide.

We’ve outlined the average lifespans of certain filter types below:

Filter TypeAverage Lifespan
Under-sink filters3-9 months
Countertop filtersApprox. 6 months
Faucet water filters2-3 months
Refrigerator water filtersAprox. 3-6 months
Reverse osmosis membranes2 years
Shower water filtersApprox. 3-6 months
Sediment filters6-12 months
Carbon filters6-12 months
Post filter cartridges1-2 years

⌛ How Filter Lifespan is Measured

Manufacturers determine the lifespans of their filters during initial product testing. In most cases, lifespan is measured in gallons – i.e. how many gallons of water the filter will treat before it becomes incapable of doing its job.

This gallon lifespan is then translated into a time period, usually in months, based on the manufacturer’s perception of the average person’s daily water usage and quality.

This is where accuracy can often be off. We’ve seen manufacturers say that their filters have a 100-gallon, or four-month, lifespan, while different manufacturers of the same filter type say that their 150-gallon filter lasts three months.

The moral of a story? Don’t take a time measurement as a given when it comes to filter lifespan. Use it more as a guideline, and change your filter before then if the flow rate becomes significantly slower, or your water starts to taste unpleasant.

Water filter cartridge

🔂 Why Water Filters Need Replacing

Unfortunately, no matter how modern the design, no water filter can last forever. Even the biggest whole house water filter cartridge will need to be replaced eventually.

To understand why filters have a shelf life, we need to look at their design.

Most water filter cartridges have a cartridge design, with tiny pores that block contaminants from traveling through.

Over time, these pores become more and more clogged, until the media is so saturated with contaminants that water can no longer easily pass through. This is where you’ll notice a decrease in flow rate and/or water pressure.

Additionally, an old filter begins to lose its integrity. Parts of the filter may wear away, creating large gaps that allow contaminants – including those collected in the media – to pass through to the other side and causing recontamination of your your water, affecting its taste.

Not only that, but bacteria buildup is likely in certain types of filter cartridges. KDF and silver-laced filters are protected against bacteria, but standard activated carbon filter cartridges aren’t. If you don’t replace this type of filter on time, you might end up drinking harmful microbes in your filtered tap water.

Let’s look in more detail at the different types of water filters and how long they last.

📏 The Different Water Filters And Their Lifespans

Different types of filters have different lifespans. Some filtration units have multiple filter stages, with filters that need replacing separately, at different times.

We’ve shared the most popular filter systems and their lifespans below.

Whole House Water Filtration Systems

Cartridge based whole house water filters typically have several filter stages, including a sediment pre-filter, a carbon cartridge (potentially combined with KDF or a similar media), and a polishing filter.

  • The sediment pre-filter has an average lifespan of 6-9 months
  • The carbon cartridge lasts for 6-9 months
  • The post or polishing filter lasts for around 24 months

Tank based entire home systems will typically have a sediment pre-filter that lasts 6-9 months, while the media in the tank itself can last between 3-5 years.

Springwell CF whole house filtration system

Under-Sink Water Filters

Under-sink water filters are essentially small, point-of-use versions of whole house filter systems, with a sediment filter, a carbon or combined carbon cartridge, and a post or polishing filter.

  • The sediment filter in an under-sink water filter lasts for up to 6 months
  • The carbon cartridge has an average lifespan of 4-6 months
  • The polishing filter lasts for 6-9 months

Faucet Water Filters

Faucet water filters have a single filter, usually made from activated carbon. Due to its small size, this filter lasts for just 2-3 months.

Countertop Filtration Systems

A countertop water filtration system has an average filter lifespan of 6 months, assuming that it’s used to purify about 1 gallon of water per day. Some filter systems last longer than this.

Reverse Osmosis Units

RO units have several filter stages, each with different lifespans:

  • RO sediment filters last for 6-9 months
  • Activated carbon cartridges last for 6-12 months
  • The RO membrane has a 24-month lifespan
  • Post-filters have a 12-24-month lifespan

Learn how to change RO filters – read this guide!

Tank-Based RO System

Shower Filters

Shower filters aren’t used frequently throughout the day, so they last as long as 6 months.

Fridge Filters

A refrigerator filter should last for up to 6 months, although some filters have a lifespan of only 3 months before needing replacement. Check the user manual if you’re unsure.

Water Pitcher Filters

A water pitcher filter or water dispenser using gravity filtration has a single filter cartridge that lasts for about 3 months, depending on the quality of your local water supply.

Continue Reading: How Long Do Brita Filters Last? Find Out Here!

📰 Factors Affecting Water Filter Lifespan

There are several factors that affect how long a water filter cartridge lasts:

Your Water Quality

We discussed how manufacturers give an estimated time period for their filter lifespans, and how this largely depends on your water quality. Here’s why.

Let’s say your water supply has relatively low TDS (total dissolved solids, a measure of charged particles in your water). When your water flows through a filter, there will be fewer contaminants for the filter to trap. This means the media will become clogged at a slower, more gradual rate, and the water filter will last longer.

On the other hand, if your water has high TDS, there will be more contaminants for the filter to remove, and the media will become clogged at a faster rate. In this case, the filter will need to be replaced more frequently.

The Type of Water Filter

Certain types of water filters are designed to last longer than others. It depends on what the filter is designed to remove, and the materials and structure of the filter.

For instance, a sediment filter in a whole house water filtration system typically has a lifespan of around six months. The filter is the first stage in a whole house water filter, so it’s likely to come across the most contaminants.

Compare this to the very final post-stage activated carbon filter in a whole house water filter system. This filter is designed to polish the water and remove any lingering harmful contaminants, most of which should have already been removed. For this reason, you shouldn’t need to replace the filter until after two years.

Gravity cartridges in pitcher water filters also have shorter lifespans than whole home or under-sink water filters for two reasons: they’re smaller in size, so they have a smaller surface area to trap contaminants; and they rely on gravity, so once they’re clogged, it’s very difficult for water to get through.

Filter type

Your Water Usage

Finally, your water usage plays a role in how long a water filter lasts.

Let’s say you buy a water filter that has a lifespan of 100 gallons.

If you use 100 gallons of water in two months, this is when the filter will need to be replaced. If you use 100 gallons in four months, you’ll get an extra two months out of the filter before you need to buy a replacement.

Not many of us would bother to track our water usage to that level of exactness. Luckily, there are easier ways to know when you need to replace a cartridge in your water filter system.

🔎 Signs you Need to Replace your Water Filter

Some of the signs that your water filter is coming to the end of its lifespan are:

Slow Water Flow

Whether you’re using an under-sink water filter, a refrigerator water filter, or a pitcher filter, a gradual decrease in flow rate and water pressure is natural.

After installing a new filter, time how long it takes for you to fill a glass of water (or, for a pitcher, how long it takes for a glass of water to be filtered). Once it starts taking double or triple the amount of time to fill the same glass, it’s time for a replacement filter.

Poor-Tasting Drinking Water

The whole point of a water filter is to improve the taste of your drinking water by removing harmful chemicals that contribute to unpleasant taste.

However, when the cartridges in water filtration systems begin to release trapped contaminants, your water will take on a nasty taste.

Person holding a glass of dirty water

Odor

Bad-smelling tap water comes hand-in-hand with poor taste.

If contaminants are present in your water, water tastes and smells bad. The only way to eliminate the smell is to replace the filter.

Staining or Floating Sediment

Finally, discolored water or floating sediment, including mold, is one of the surest signs that you need a new filter cartridge.

Don’t delay changing your filter if you notice staining or sediment. Your water could contain iron, manganese, arsenic, copper, sulfate, volatile organic compounds, or even microbiological contaminants.

📌 Takeaway

No water filter lasts forever. If you want constant access to filtered water, make sure you replace your cartridge on time.

Our advice is to keep a stash of replacement filters in your cupboard, so that when you notice it’s time to replace your existing cartridge, you can do so instantly.

Worried you won’t notice any of the signs that your drinking water filter needs replacing? Check your product’s user manual to see how many months it should last. Then, on the day you replace the filter, mark your calendar with the date you need to make the next replacement.

Alternatively, look at filters with filter change reminders. Some filters have a traffic light system, switching from green to amber to red, to let you know when the filter needs to be changed.

If you need help replacing a water filter cartridge in a whole house water filter system, check out our complete guide here.