How Often Should You Replace Your Under Sink Water Filter?

Author: Jason Hollow - Published: 2021/09/24 - Updated: 2022/11/22

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One of the most important appliances in your kitchen, your under sink water filter, deserves respect and consistent upkeep.

After all, the workhorse ensures you have access to safe and clean drinking water throughout the day. In return, all you need is to replace the filter cartridges at the specified time. But that’s where it gets complicated.

You see, all under sink systems are not built alike. Therefore, some require filter replacements every three months, while others can last for six months or longer. Apart from the type of under sink water filter (single-stage, multi-stage, reverse osmosis), the source water quality and day-to-day consumption also influence cartridge service life. Don’t worry, though; we got you covered!

So, here is our guide on how often to change an under sink water filter!


  • The average lifespan of an under sink water filter before you need to replace it is around six months.
  • Its lifespan largely depends on your water usage, water quality, and the capacity of filtration.
  • Telling signs that you need to replace your under sink filter would be if your water (1) starts to taste bad or smell unpleasant, (2) looks turbid, or (3) if you experience low pressure.

Under Sink Water Filters: What They Do + Benefits

Under sink water filters provide you with a vast array of benefits, making them one of the most popular types of home water purification systems on the market. Thanks to easy installation and upkeep, most homeowners are thrilled with their under sink filter units.

They are point-of-use devices that require limited space and provide you with filtered water for cooking and drinking, all at a minimal cost per gallon.

Most under sink water filters do an exceptional job at making your water taste and smell much better by removing chemicals such as chlorine and pesticides etc.[1]

What’s best is that some top-quality filtration systems can even effectively remove heavy metals, most organic and inorganic compounds, bacteria, viruses, salts… – making your water spring fresh.

So, you can finally experience contaminant-free hygienic water right in the comfort of your home.


  • Most under sink water filters are dependable and affordable, and the best ones out there have something for everyone. Thankfully, their prices don’t define the utmost convenience they provide in terms of service life, contaminant removal and ease of usage.
  • With regular maintenance and periodic cartridge replacements, under sink filtration systems will easily last you a decade.
  • Moreover, these systems require minimum installation with no permanent changes to your house’s plumbing.
  • Since they are set up in your kitchen, the filters are easily accessible for replacements and general upkeep.
  • Unlike water filter pitchers, under sink filters produce clean filtered water at demand. On hot summer days when your family requires more water for drinking, you no longer have to repeatedly fill filter jugs and wait for them to work.
  • Perhaps the biggest benefit of an under sink water filter system is that it allows you to bid farewell to plastic bottled water – undoubtedly, a bane for your planet and pocket.

How Long Do Under Sink Water Filters Last?

How Often to Change an Under Sink Water Filter Thumbnail

A water filtration system is only as good as its filter elements. So, if you are using the #1 under sink filter but are irregular with cartridge replacements, it will be completely useless.

Similarly, if you follow the manufacturer’s instructions to the dot without analyzing your individual situation, you might end up replacing perfectly functional filters.

Here are the factors that influence how often you need to change your under sink water filter.

Water Quality

Your water’s quality will vary considerably depending on where it was sourced from – private well or municipal water board.

Water from wells is typically high in sediment and possibly microbiological compounds since it has never seen the light of any filtration plant. At the same time, city water is already treated to standards set by the EPA.

Naturally, the higher the level of contamination, the quicker your filters will clog regardless of their quality and vice versa.

Type of Filter

There are many types of filter cartridges available in the market with varying degrees of filtration capacity. For instance, the lifespan of a carbon-based filter will depend on the amount and quality of activated carbon used in it.

Some good quality ones will last you as long as nine months while others will exhaust in under six. Make sure to check the recommended filter replacement frequency.

Water Usage

A water filter’s lifespan is measured through the number of gallons it can treat. Typically, sturdy under sink water filters can treat 500 to 1000 gallons. Depending on the size of your family and daily usage, you may need a replacement in as little as six months or as long as 12 months.

Unmistakable Signs an Under Sink Water Filter Change Is Required

With so many factors influencing your filter life, it is natural to feel confused. So, here we mention a few signs indicating that a filter change may be required, that you should never miss out on.

  1. Slow filtering speed: Is it taking you longer than before to fill a glass of water? More often than not, a clogged cartridge is to blame. When your filters become full of gunk, they restrict water flow significantly, and therefore you experience a noticeable pressure drop.
  2. Poor taste and smell: If you notice foul-smelling water, it is a giveaway that your filters are clogged beyond usage.
  3. Floaty bits in your water: If you see tiny particles swimming around your glass of water, it’s an obvious sign your under counter filter has aged beyond usage.
  4. High total dissolved solids (TDS) level: Many people access their water quality by measuring TDS levels, especially for RO filters. If you see a sharp increase in the TDS reading of your water (anything over 20%), it suggests a poorly functioning filter. Just keep an inexpensive TDS monitor handy if you suspect poor filtration. Please keep in mind this method does not apply to all filtration technologies.

Is Changing the Filter Really That Important?

Should I change the cartridge on my under sink water filter; this is a question we get asked quite frequently. The answer is yes, yes, and a thousand times yes!

Thankfully, filter replacements for under sink units are virtually tool-free, sweat-free, and extremely quick. Here is why you must ensure timely replacements.

  • In short, an old filter is equivalent to no filter. Thus, you might be exposed to a host of contaminants as they swim by your clogged cartridges.
  • All filtration systems bring about a standard drop in water pressure which is almost unnoticeable. But as filters get entirely clogged, you might experience very slow filtering speed and poor flow rate.
  • Failure to replace a jammed cartridge will result in your water flowing out from the top of the housing. Not only will it damage the cupboards and flood your kitchen, but it will also result in additional servicing expenses.


The replacement cost for NSF-certified under sink filtration units[2] can range between $20-$100 for a set of three filter cartridges. If you choose to buy generic replacements on the market, you may find them at a lower price, but you never know what quality you will get.

two water filter cartridges dropped in water

Pro Tips

Here are a few bonus tips to help you maintain your under sink filter unit:

  • Keeping a log of your recent filter replacements will help you determine how long your filters typically last. Write it down in a notebook, set an alarm or simply subscribe for replacement cartridges to arrive at the required time through trustworthy brands like Clearly Filtered.
  • Always inspect your sediments filters closely when you remove them from the sump. If they still look clean and functional, you may want to consider sliding them back and replace after a few days/weeks.
  • Even though it may sound contradictory, it must be said out. Don’t wait for your filtration speed to go very slow. Sometimes, a clogged cartridge will not bring about a change in water pressure and seem perfect as a new one. So, you must keep track of the last few replacements to take out the guesswork.


In conclusion, under sink water filters have many benefits; most importantly that they provide clean drinking water that’s safe to consume.

But, you can only gain from these benefits if you maintain your system properly, meaning making timely filter replacements.

How often depends on your water quality, the type of under sink water filter and your water usage.

Tell-tale signs that a filter replacement is due include slow filtering speed and poor water taste/smell.

If you don’t change filter cartridges regularly and on time, an under sink filter may do more harm than good.

The cost for replacement filters is manageable. In addition, writing down the date of the last filter change helps a lot.

Further Reading


Meet Jason Hollow

Jason Hollow Jason is the founder of Water Masterz and head of content creation. After six years in the industry, he has tremendous knowledge and first-hand experience on all things related to water treatment.

His credo: Not a single American should have to drink unhealthy water at home.

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