Finding an affordable yet effective water filtration system is a challenge for many people. Trying to understand all the subtle differences between models and the fear of installation can scare people away from transforming their drinking water.

best under sink water filter

The under sink water filter is one of the most popular choices among homeowners for several reasons. In addition to them being affordable, they are easily installed by almost anyone and have very little maintenance.

If you are looking for an alternative to spending big money on a whole-home filtration system, then an under-counter water filtration system may be right for you.

In this guide, you will learn everything possible about under-sink water filters. We will go through all those subtle differences and help you decide which is the best under-sink water filter for you. There are a ton of options to choose from, but with our guide, we are confident that you will find a great option to improve your drinking water.

Don’t Have Time To Read? My Top 3 Under Sink Water Filter Picks

Home Master TMAFC-ERP Artesian Full Contact Undersink

Editor’s Choice
  • It will remove 99% of 77 types of contaminants.
  • NSF certified on standard 42, standard 53, standard 401, and +P473.
  • The filter life is roughly 600 gallons, which is great for families of all sizes.

Clearlyfiltered 3-Stage UnderSink Filter System

  • It has the ability to remove over 99.9% of waterborne contaminants
  • It comes to combatting fluoride and lead at an effective rate of over 99.5%.
  • The installation simply could not be easier. It takes a mere 10 minutes on average to install.

iSpring CU-A4 4-Stage Premium Under Counter System

  • Ultra Filtration Filter-contains hollow fiber membrane technology with a pore size of just 0.01 microns.
  • It will get rid of 99% of contaminants.
  • The filters are simple to change. They twist on and twist off with ease.

First, Why Should You Install an Under-Sink Filter?

This is one of the most common questions we receive, and to be honest, there are so many reasons why!


Most people are on a budget. One way to avoid blowing that budget on eater purification is to investigate under sink water filters rather than whole-home systems. Whole-home systems can be upwards of $500+, and that does not include any costs associated with installation.

Under-sink systems are affordable, and since most homeowners can install these in just a few hours, you are saving hundreds more on installation costs.


Many people associate affordability with weaker product performance. When it comes to under sink water filters, this is not something you need to worry about.

Thanks to the evolution of home water filtration throughout the past decade, a simple under-sink water filter system can provide all the benefits of a whole-home system.

You can remove thousands of different pesticides from your drinking water and sink water with a quality under-sink water filtration system.


Since most under-sink water filters can fit into an average-sized moving box, it is easy to uninstall and bring your water system with you. If you are moving or want to bring your clean water system to your lake home or cabin, it is simple to do so with an under-sink water filtration system.

Uninstalling is usually easier than the initial install, and you cannot put a price on clean drinking water, so it makes sense to keep the system with you wherever you go.

Types of Under Sink Water Filters

There are different types of under-sink filters, and each has its own unique characteristics.

Simple Under-Sink Water Filter

The best way to define a Simple Under Sink Filter is that it connects to your already existing water line, and the water will flow out of your already existing faucet. These are usually the cheapest options for under-sink filters, but they can be very effective at reducing harmful traits within your water. Another benefit of these filters is that they can easily be adapted to use with any water line in your home. This could include a refrigerator line or an ice maker.

One thing to remember with the Simple Under-Sink Filters is that because there is not a dedicated faucet to the clean water, you will be using it for everything. This will cause your filters to need to be replaced more often because there is more water running through them daily.

Conventional Under-Sink Water Filter

Like the simple filter type, the Conventional Under Sink Water Filter will connect to the cold water line under your sink.

The difference is that the Conventional style will come with a dedicated faucet and tap water. This gives you a reserved filtered water line to use at your disposal on your countertop. This is beneficial because you can still use your sink’s normal faucet for dishes and other water uses.

It will also allow you to use the hot water at your kitchen sink because you will not be using the dedicated faucet with filtered water. You will also see a longer filter life because you are not using the filter for every water need you have within the kitchen.

Some people worry about the installation of a new faucet on their countertops. This is a legit concern and something we deal with on a weekly basis. Make sure you do not already have a hole drilled for the dedicated faucet.

It could be hiding underneath a cover, which looks like a flat disc. It is usually the same color as your faucet. If you do not have an already drilled hole, it is easy, but if you are not comfortable with it, a simple system may be best.

Reverse Osmosis Water Filters

Reverse Osmosis (RO) systems use a multi-stage filtering process along with a tank system that is there to “flush” away contaminants in your water supply. The tank system usually contains a type of resin that lets clean water through and absorbs pesticides.

Almost all RO systems available come with a dedicated faucet (Conventional Filter), and this will save money on filter replacements and gets you the most out of your under-sink water system. The RO systems are widely regarded as the most effective under-sink water filtration option due to their ability to use reverse osmosis filters and typically water filtering stages.

One of the drawbacks of a RO filter system is the need for the system to produce wastewater after the RO system. Any water that was not let through the RO process needs to drain, and this is considered a waste of water by many. Another thing to consider with a RO filter system is the installation and costs can be more to bear than other types of under-sink water systems.

Many RO systems are becoming easier to install, but there are a few more moving parts than other types. The cost of the RO system is usually more than other systems, but remember, you are getting the highest quality water filtration available.

Best Under Sink Water Filter Reviews

1. Home Master TMAFC-ERP RO Contact Undersink

Highlighted Features

  • It has seven stages of filtration and water enhancement.
  • There is a built-in permeate pump to reduce water waste.
  • The filter can be replaced quickly and painlessly with no need for tools.
  • It includes a dedicated tap to add to your kitchen sink for reliable drinking water.
  • This uses Reverse Osmosis (RO) to clean and purify water.

The number one lead removing water filter on our list is at the top for a reason. The Home Master is a simple under sink filtering system that provides a dedicated water faucet for clean drinking water. The only model on our list that uses reverse osmosis water purification has a 7-stage filter to make your water as clean as it can be.

Installation was a breeze, and with a long-lasting filter, the amount of maintenance required on this system is minimal. It is hard to go wrong with the Home Master water purification system if you are looking to remove lead from your water. Upon testing the treated water, we saw a huge drop in traceable lead particles!

What We Like:

  • It can be easily be installed by the homeowner.
  • The package includes all parts needed to install and has a 5-year warranty from the manufacturer.
  • The flow rate was not reduced, like some under sink water filters.
  • Before and after water testing showed that the filtration system removes a high number of contaminants.
  • The water filter adds minerals to your water, making it healthier and more refreshing.
  • The filter lasts for up to 2000 gallons of water, which is around 1-year of normal water usage.

What We Didn’t Like:

  • The water feed adapter and shut-off valve only come in 3/8-inch sizes.

Here is how to install the Home Master TMAFC under your counter:

2. iSpring CU-A4 4-Stage Premium Under Sink System

Highlighted Features

  • This system combines 4 stages of filtering ranging from a 5-micron pre-filter to an ultra-filtration level which includes a 0.1-micron filter, which is among the finest filters available.
  • Because this is not a Reverse Osmosis Filter (RO) system, there is no wastewater involved, which saves thousands of gallons over the course of a year.
  • The filters are simple to change. They twist on and twist off with ease, and there is no need to disconnect the water hose.

The iSpring CU-A4 under-sink filter features multi-level filtration with a dedicated chrome finish faucet that provides you and your family with clean and crisp water all day long. It has a compact design that allows it to be easily installed under the sink. It was designed to be installed by the homeowner, and thanks to iSpring’s detailed technical documents and excellent virtual support, almost anybody can install this system.

Each filter has a specific role when it comes to water filtration to ensure that virtually nothing will sneak through the filtration process. To begin with, the first filtering stage has a 5-micron filter that is designed to specifically target larger in-soluble elements like heavy metals.

This stage is followed by an ultra-filtration stage that features a 0.1-micron filter that can capture both soluble and insoluble elements. The remaining stages feature an activated carbon filter that helps with odor and taste while ensuring that calcium and other valuable minerals stay in the water.

iSpring provides wonderful warranty and guarantee options that allow you to be completely refunded within one year after purchase and also covers all components.

What We Like:

  • We really appreciate the compact design and size of this filtration system. It fits extremely well under any sink and is a breeze to install.
  • The water pressure stays strong, and can easily handle cleaning dishes, washing veggies, and anything else you wish.
  • It comes with a 1-year moneyback guarantee and a 1-year manufacturer’s warranty that covers all components.

What We Didn’t Like:

  • It takes a lot longer for the filters to be refreshed after changing. Expect there to be an odd taste for a little while.

3. Clearlyfiltered 3-Stage Under-the-Sink Filter System

Highlighted Features

  • This 3-filter system comes fully equipped with everything you need to easily install this into your existing cold water line.
  • It has the ability to remove over 99.9% of waterborne contaminants, which amounts to over 230 total toxins.
  • The water lines are made from flexible stainless steel that is much longer than most water lines and easily attached to the water inlet.

The 3-stage water filtration system by Clearly Filtered is one of the easiest yet most effective water filters we have tested thus far. The combination of filters does a wonderful job ensuring that your water is among the best available, at a fraction of the price compared to other water purification systems. There are 3 unique filters that each target a specific type of contaminant, and water testing has proven that this 3-filter combination tests off the charts.

It is one of the best DIY filtering systems on the market when it comes to combatting fluoride and lead at an effective rate of over 99.5%. With a price tag of under $500, the test results for this system prove that you will get the most value out of this filtering system than almost any other on the market.

The average installation time of the Clearly Filtered system is around 10 minutes, and when it comes to changing the filters, it can be done with no tools and takes mere minutes. The long, stainless-steel water lines are among the easiest materials to use, and since stainless steel has a natural anti-bacterial quality to it, you do not have to worry about mold and mildew build-up.

What We Like:

  • Each filtration stage has a unique but targeted group of contaminants that do a wonderful job of eliminating common contaminants like tastes/odors associated with chlorine, heavy metals & VOCs, and then finally, the fluoride stage.
  • The installation simply could not be easier. It takes a mere 10 minutes on average to install this, and no plumber is required. The mounting plate is tough and sturdy, too.
  • The taste of the water was improved more than we expected. You can also see the difference in water clarity after installation is completed.

What We Didn’t Like:

  • The water pressure is noticeably lower after installation. It still works fine, but it could definitely be improved.

4. AO Smith 2-Stage Under Sink Clean Water Faucet Filter

AO Smith 2-Stage Under Sink

Highlighted Features

  • This system is certified on NSF/ANSI standards: 42, 43, and 401.
  • It has two separate filtering stages and a dedicated chrome faucet.
  • The filters will last for around 500 gallons of usage.
  • The flow rate is 0.5 gallons per minute (GPM.)

AO Smith has been famous for water products for many years. This filtration system is exactly why. They packed a lot of features into such a small package.

It is the smallest filtration system in this article, but you are not missing out on much, even with only two filters. Chlorine, lead, and fluoride levels were all lowered with this filter.

I cannot stress enough how simple the installation of the AO Smith under-sink system was. All the parts needed to install are included, and the only real tool you need is a little wrench that also comes with the system. Maintenance will be very limited with this system thanks to its 500-gallon filter life, the 2nd best in this entire article.

What We Like:

  • The faucet is one of the nicest ones we have installed; it is solid and sleek.
  • Since there are two filters, this is the smallest unit on our list and fits under any sink.
  • The installation was the fastest of all the filters we have reviewed thus far.
  • With a price of under $150, the value is great for the number of elements being removed.
  • Five hundred gallons of filter usage is very long and will save money in the long run.

What We Didn’t Like:

  • The flow rate of 0.5 GPM is very slow.

5. CuZn UC-200 Under Counter Water Filter

CuZn UC-200 Under Counter

Highlighted Features

  • The filters can last up to 5 years, which is a ton.
  • It is designed to connect directly to your sink’s cold water line and use your existing faucet.
  • There are three unique stages of water filtration that remove chlorine and other tap water contaminants.
  • The filters are made from a bacteriostatic material that will not get moldy.

When it comes to the CuZn under-sink filter, let’s start with the obvious. 50,000-gallon filter life is insane. On average, that is five years with the same filter. If the filters were constructed of carbon like many others on the market, five years would be way too long, and you would see bacteria and mold build-up. But with the CuZn filters, are made of a bacteriostatic material that resists bacteria growth around the filter.

The under-sink filter is larger than most and heavy, but the benefits you get from making it fit are awesome. Chlorine and other tap water contaminants were removed from the water, and other elements like lead and fluoride were removed as well. The flow rate on the CuZn system is also on the top-end of all the under-sink filters we have reviewed this far.

What We Like:

  • The filter life is 50,000 gallons, which is far and away from the longest we’ve seen.
  • The installation was simple and straightforward. The only piece is an all-metal hose that attaches to your current water line.
  • The flow rate is on the higher end at 2 GPM.
  • The connector on the water line is a high-quality brass that will not bend or break.
  • Chlorine levels were virtually zero after testing the water.

What We Didn’t Like:

  • The filter is larger and heavier than most other under-sink models.
  • TDS levels were not reduced.

6. Brondell Circle Under Sink Reverse Osmosis System

Brondell Circle Under Sink

Highlighted Features

  • It is a RO filter system that has a 6-liter tank.
  • There is an included chrome tap and faucet.
  • There is an LED filter change indicator.
  • It has four unique stages of filtration
  • It is certified by NSF/ANSI on standards: 42, 53, 58, and 372.

This is by far, the unique RO system we have ever had the pleasure of testing. Instead of your traditional RO system that comes with a set of filters and a large tank, everything you need for the Brondell is encapsulated within a sleek black box. The box is not the smallest thing in the world, but it can still easily fit under all sinks.

One of the biggest complaints we get about RO systems is the time it takes to regenerate. During this time, clean water is not available from your filter. Some systems can take hours to refresh, but the Brondell takes only 25 minutes on average.

In addition to that, the amount of wastewater is significantly less than other RO systems. It does a great job removing chemicals from water and even got rid of those pesky total dissolved solids!

What We Like:

  • The RO tank is made from a flexible material that works with a valve to ensure consistent water pressure.
  • The time it takes to refill the RO tank is the fastest we have seen in this review so far.
  • The RO membrane features an automatic filter that flushes and cleans all filters, which extends the life of the filters to almost two years.
  • The design of the system is all encompassed in a single square shape. The footprint of this RO system is smaller than any other system we’ve reviewed.
  • Water testing showed that total dissolved solids (TDS) were considerably lower, which is a rarity for under-sink systems.

What We Didn’t Like:

  • The cost of replacement filters is more than comparable models.

1. Aquasana 2-Stage Under Sink Water Filter System

Highlighted Features

  • It will remove 99% of 77 types of contaminants.
  • There is no waste associated with the system because it does not use reverse osmosis.
  • NSF certified on standard 42, standard 53, standard 401, and +P473.
  • There is an included faucet that comes in 3 different color/finish choices.

Aquasana has a knack for providing consumers with affordable yet effective water filtration systems. This under-sink model is no exception as it does a wonderful job of removing dozens of contaminants while retaining healthy minerals found in water. The under-sink system is easy to install and does not take up a lot of space under your kitchen sink.

The faucet included with the filtering system is made from high-quality components and is lead-free, so you know it is safe. It comes in 3 unique finishes so you can choose the hardware that matches your kitchen the best.

This system has the most certifications from NSF that we have seen in a filter and is pioneering the fight for the perfect water filtration system. The filter life is great and averages around six months of life before needing to be replaced.

What We Like:

  • The 2-Stage filter system will remove pesticides while retaining healthy minerals like calcium.
  • Water testing proved that lead was greatly reduced after filter installation.
  • The installation was quick and straightforward. I think most homeowners would be able to handle it with ease.
  • The activated carbon filter does a good job of removing chlorine smells and tastes from water.
  • The filter life is roughly 600 gallons, which is great for families of all sizes.

What We Didn’t Like:

  • The flow rate after installation is slower than I prefer.

7. Aquasana 2-Stage Under Sink Water Filter System

Highlighted Features

  • It will remove 99% of 77 types of contaminants.
  • There is no waste associated with the system because it does not use reverse osmosis.
  • NSF certified on standard 42, standard 53, standard 401, and +P473.
  • There is an included faucet that comes in 3 different color/finish choices.

Aquasana has a knack for providing consumers with affordable yet effective water filtration systems. This under-sink model is no exception as it does a wonderful job of removing dozens of contaminants while retaining healthy minerals found in water. The under-sink system is easy to install and does not take up a lot of space under your kitchen sink.

The faucet included with the filtering system is made from high-quality components and is lead-free, so you know it is safe. It comes in 3 unique finishes so you can choose the hardware that matches your kitchen the best.

This system has the most certifications from NSF that we have seen in a filter and is pioneering the fight for the perfect water filtration system. The filter life is great and averages around six months of life before needing to be replaced.

What We Like:

  • The 2-Stage filter system will remove pesticides while retaining healthy minerals like calcium.
  • Water testing proved that lead was greatly reduced after filter installation.
  • The installation was quick and straightforward. I think most homeowners would be able to handle it with ease.
  • The activated carbon filter does a good job of removing chlorine smells and tastes from water.
  • The filter life is roughly 600 gallons, which is great for families of all sizes.

What We Didn’t Like:

  • The flow rate after installation is slower than I prefer.

8. iSpring US31 3-Stage Under Sink Water Filtration System

iSpring US31 3-Stage

Highlighted Features

  • Three filters that each target a different group of contaminants.
  • It includes a brushed nickel designated tap and faucet.
  • Each of the three filters will last between 6 and 12 months, depending on usage.
  • Flow rate is maximized at one gallon-per-minute (GPM) when PSI is maximized.

As they say, simple is best. This under sink unit is a simple yet effective water filtration system. First off, the price is just right, less than $120 for a unit that does so much is a great deal.
The 3-stage filtration is effective at removing tons of tap contaminants.

I noticed right off the bat that there were no odors or tastes associated with chlorine in the water, which is one of the most common complaints we receive.

The installation is simple enough for most homeowners, and I love that iSpring provides everything you to install and much more. There was enough water tubing to install the system 3 or 4 times, making it nice and easy to bring your under sink water filter with you when you move.

The water pressure stays consistent over time, unlike some filters that slow down once they have been in place for a few days.

What We Like:

  • The size of the filters is great, and they fit easily under the sink.
  • At less than $120, the value that you are getting is unmatched.
  • The tubing that is included to connect the filtration system to the water line is solid, and iSpring provides a ton of it!
  • The installation of the product was smooth and easy. They have a ton of resources available for you to learn from.
  • Water testing proved that common tap water pesticides were lessened while calcium, sodium, and magnesium were unaffected.

What We Didn’t Like:

  • We have heard reports of a slight drip from the included faucet.

9. Express Water Reverse Osmosis Water Filtration System

Express Water Reverse Osmosis

Highlighted Features

  • It combines reverse osmosis (RO) and a 5-stage filtration system.
  • There is an included brushed nickel tap/faucet included with the unit.
  • There is a 1-year manufacturer guarantee on all parts.
  • Filter changes are simply due to a release button.

I think Express Water has a winner on their hands with the RO5DX. It is an extremely user-friendly water filtration system thanks to its easy filter removal and color-coded filter labeling system.

Each filter has a dedicated job to do when it comes to filtering the water, and the filter labels identify what that is, and they each have a unique color.

With five different filters, it would be easy to get them confused with one another, and if that were to happen, you would not have the best filtering performance.

In addition to user-friendly attributes, the brushed nickel faucet looks very modern and luxurious. The RO system has a few safety filters built-in to avoid leaks, and the included RO tank stand ensures that the tank will stay upright, avoiding massive issues.

The tank is sleek and does not take up a ton of space under your sink. The 50 gallons of water it produces a day is massive as well. The average adult needs around 1 gallon/day to stay fresh.

What We Like:

  • The 5 different filters are clearly marked and color-coded for an easy replacement filter.
  • This RO system can produce 50 gallons of water per day, plenty for any family.
  • There is a shut-off valve included that detects any leaks or excess water in the system, which is a great feature to avoid flooding your kitchen!
  • The water line can take both ½-inch and 3/8-inch fittings using an adapter that is included.
  • There is a tank stand included for the RO tank so you do not move at all. These are rare, and I appreciate the detail that Express has added here.

What We Didn’t Like:

  • The flow rate is 0.8 GPM, which is on the lower end of the spectrum.

10. iSpring RCC&AK 6-Stage High Capacity Under Sink System

iSpring RCC&AK 6-Stage

Highlighted Features

  • It has six different stages of water purification and utilizes reverse osmosis (RO.)
  • The filters will remove over 1,000 different contaminants like chlorine and lead.
  • There is a European-style brushed nickel water faucet included with the filtering system.
  • The alkaline filter stage adds valuable minerals and raises the water’s pH level.

This system has a ton of filtering levels and is one of the best at removing a wide variety of water contaminants. Testing showed that pH levels were increased. This is due to the 6th stage of the filtering process, where the alkaline remineralization process takes place. During this process, healthy minerals are restored into the water, and the pH becomes more balanced and less acidic.

Since there is more than just a single water tube with this system, iSpring provides color-coded tubing to allow for easy installation and identification.

If you were to attach the wrong hosing to the RO portion, you could be dealing with a leak or two, and thankfully, iSpring is proactively trying to prevent this. The included brushed nickel faucet has been great thus far, and I have yet to see any leaking from it.

What We Like:

  • Comparing this alkaline filter to the non-alkaline system, you can taste the difference in the water.
  • The maximum water production is 75 gallons/day, which is more than enough for any family.
  • Unlike many undersink water filters, the iSpring RO system removes several total dissolved solids, which is a great feature.
  • The installation involved with this system is simple, but this system includes more features, so it can be intimidating. However, the company has numerous YouTube videos and other materials to help.
  • The RO tank is smaller than most systems but is still capable of producing a ton of water each day. I like this because I can fit it just about anywhere.

What We Didn’t Like:

  • The system produces 2 gallons of wastewater for every 1 gallon of filtered water.

11. APEC 75 GPD 6-Stage Ultra Safe Reverse Osmosis System

APEC 75 GPD 6-Stage

Highlighted Features

  • This multi-stage filtration and a Reverse Osmosis (RO) process provide you with safe, and clean drinking water,
  • It is designed to be installed by the homeowner, and it is not a difficult installation process. APEC provides in-depth installation instructions, online support, and DIY video instructions.
  • The entire purification system is certified by the Water Quality Association (WQA), which is a 3rd party testing group that ensures that consumers are getting quality water filtering products.

When it comes to choosing an effective and efficient under-sink water filter, size is one of the most important aspects you can consider. If you are dealing with a small space or have a crowded cabinet underneath your sink, you will need to ensure that the water filtration system you choose fits. The APEC system provides all you could ever want in a water filtration system while minimizing its footprint, allowing it to fit virtually anywhere.

It comes with 6 unique stages of filtration and a quiet, efficient Reverse Osmosis (tank.) The filters test off the charts when it comes to removing pesky contaminants that are commonly found in municipal water supplies. Things like odors, tastes, and foggy water will be immediately improved upon installation thanks to 2 carbon block filters that help remove these things. Additionally, there are several other filters that help eliminate sediment, lead, and other heavy metals. The filters have a long lifespan and are easy to change, too!

One of the things we are most impressed by the APEC system is the included chrome finished faucet. It is extremely elegant, has a steady water flow, and the entire faucet swivels 360-degrees. It is far better than many other faucets that the competition includes.

What We Like:

  • The faucet is top-notch when comparing it to other RO systems. It is sleek, clean, and, most importantly, provides us with a phenomenal flow rate.
  • We really appreciate APEC’s customer service and the warranty they offer. They include a 2-year manufacturer’s warranty on all components.
  • Water testing has proven that the APEC system will reduce over 99% of contaminants that are common among city water supplies. For the price, you cannot beat it!

What We Didn’t Like:

  • The ball valve on the tank is plastic, which is easily prone to breaking. We prefer brass.

12. Woder WD-S-8K-DC Water Undersink Filtration System

Wonder WD-S-8K-DC

Highlighted Features

  • It is designed to be used in conjunction with pretreated water from a municipal supply.
  • There is no plumbing required; the 3/8-inch hose is designed to connect directly to the existing water supply.
  • It is certified by WQA for chlorine removal and lead-free compliance rules.
  • The flow rate is 2 gallons per minute (GPM) when water pressure is set at 65 PSIG.

One of my favorite things about this filter is that the flow rate of the faucet is not affected at all! That trait alone is worth its weight in gold for me. The Woder under-sink filtering system is a small, sleek system that fits under your sink without taking away any precious storage space. Installation was simple, and filter changes will not provide any headaches down the road either.

Combine the simplicity of the system with the fact that it is a WQA certified system for lead removal, and you have the total package!

We trust the WQA, but since we run independent testing, we had to check the lead levels ourselves. Sure enough, there was a noticeable reduction in the lead, other heavy metals, and chlorine.

What We Like:

  • One of the simplest units I have ever seen, it is truly maintenance-free after installation.
  • The Woder model claims to remove harmful contaminants but leaves healthy minerals and according to my water testing, this was true.
  • The small size was easy to install under the sink and is not noticeable at all.
  • Water testing revealed a decrease in several different water-based contaminants, including lead!
  • The taste of my municipal water supply improved dramatically within minutes of installation.

What We Didn’t Like:

  • It does not work well with water supplies that are coming from well water.

How I Picked The Best Under-Sink Water Filter?

There are several important factors I considered when choosing the best under-counter water filter.

Flow Rate

There is a fear from homeowners that adding a filtration system of any kind will slow their water down. To an extent, this is true. After all, the water is going through multiple levels of carbon, stone, and other filtration mediums. But filtration manufacturers are constantly working toward maximizing flow rates.

Flow rate is calculated by Gallons Per Minute (GPM,) and this will vary from 0.8 to 2 GPM depending on the under-sink filter. One thing that factors into your flow rate is the PSI of the water supply. This is largely something that you cannot control, but it will dictate the flow rate of your filtering faucet to some extent.

Size and Filtering Capacity

When deciding on an under-sink water system, you must consider the space you have beneath your sink and the size of the filtration system you want.
Personally, I have a lot of space under my kitchen sink and can fit under virtually any sink. Reverse osmosis systems will have the added tank, so if you are looking to save space, you may want to look in another direction.

Additionally, some of the more advanced systems have 5 or 6 filters that will need to be mounted to something, usually the inside of the cupboard. Make sure you have the space to accommodate your choice.

One of the best things about the standard and conventional undersink water filters is that they do not have a maximum capacity of water available. Because they are installed directly into your water line, you have access to the exact same amount of water as before. This is an excellent attribute to under-sink systems and one of the many reasons why people choose these over filtering pitchers or alternatives.

Remember, with a RO system, there is a tank, and it needs to be refreshed every so often.

Technically, you would not have unlimited access to water with a RO system. However, RO tanks can now accommodate over 50+ gallons of water every day. Trust me, 50 gallons of water is a ton, and I am sure they will last long enough for your daily use.

Micron Ratings

While you are doing your research, I am sure that you will come across the term Micron. In water filtration, Micron ratings mean that the filter can filter out particles of a specific size. For example, if a filter has a rating of 0.5 Microns, this means that the filter will remove anything BIGGER than 0.5 Microns. The smaller the number, the better when it comes to water filters.

Water contaminants are so small that we cannot see them with our naked eye, and there are some micro-organisms that can sneak through without the proper filter.

Ease of Installation and Filter Change

To many homeowners, the installation and the filter maintenance is their biggest worry about purchasing an under-sink water purification system. The truth is the installation and will entirely depend on the filtering system that you choose. They each have different requirements and depending on the number of filters, some may take longer to install than others.

Luckily, our favorite companies have been working tirelessly to provide us with products that are easily installed by the homeowner. Every under sink filter in this article can be installed by the homeowner.


One thing to consider about installation is the differences between RO systems and standard/conventional systems. RO systems have more parts to them and usually have multiple hoses to bring water into the tank and out of the tank. Usually, they can still be installed by the homeowner with no issues, but it is something to consider. Standard and conventional filters usually have just one water line to deal with and are usually installed in an hour or two.

Filter changes are another thing that turns homeowners away from water filtration systems. Luckily, the more this filtration technology evolves, the easier it gets to remove filters. Many of the filters have a quick-release button or can be popped right out with a little force. Each model is a little different. Research the filter releases and decide which one you prefer before buying an under-sink filter.

Filter Cartridge Longevity

When it comes to filtering changes, there are a few factors to consider. Every filter has a rating based on how long it will work. This is usually calculated by total gallons of water and, in some cases, by months used. The more people and water you use daily, the more that will shorten the lifetime of the filter.


Consider the total amount of water your house will use daily and make sure that the filtering model you choose can handle enough water for a long period of time. Replacement filters are not free, and if you’re replacing a filter every other week, the dollars will start to pile up. And honestly, constantly having to change filters is annoying.

One other thing to consider with filter cartridge longevity is the filter change reminders. Some filtering systems will provide stickers so you can write down the date you replaced them, so you know when to get a new one. Others have a service that you can sign up for that will text or call you whenever it is time to get a new filter. This is not an exact science because they do not know your actual water usage, but it is a nice reminder to keep an eye on your filter.

Warranty & Support

Having a solid warranty on an item as important as your under sink water filters is a huge weight off your shoulders. You do not have to worry about having the funds or time to go on another shopping trip to find yet another under-sink water filter.

All the filters we’ve reviewed thus far offer a warranty of some sort. If you are looking to get longevity out of your filters, then choosing a company with a longer warranty would suit you well. Make sure you read the fine print, though!

In today’s day and age, finding quality technical support can be quite the process. If you are going to attempt to install an under-counter water filter by yourself, having somebody there right away is worth its weight in gold. Many companies are offering 24-7 phone support services to answer all your installation and maintenance questions. Another thing to look for is a company that provides detailed online videos of installation tips and tricks. In my experience, this is the best way to learn how to install, and many companies are offering these for free!

How Does an Under Sink Water Filter Work?

One of the reasons why under-sink systems are so popular is the simple design and the lack of additional electronics or batteries needed to make it run. The reason it is referred to as an “Under-Sink Water Filter” is straightforward.

They are designed to be able to fit under a sink and in a cupboard completely hidden from the outside. There are filters, water tubes, and sometimes tanks from RO systems, and nobody wants these to be out on the countertop water filter.

An under-sink water filter essentially works like a buffer between your water line and faucet. Your water line coming from your main water supply attaches to the filtration system so that water flows directly through the filtration system and up into your faucet. Most of the time, the filter is connected to your cold water line, as this is what you will use for drinking water.

Under-Sink Filters vs. Countertop Filters

A popular question we get is the difference between under-sink filters and countertop water filters. For your personal awareness, a countertop filter is a water filtration system that sits on your counter that either has a fill tank or is connected to the waterline. If it is connected to your water line, it would have a filter and faucet built into one device that is mounted next to your current sink.

The reasons people like the countertop filters are because they are typically very affordable and do an admirable job of filtering water. They are also very easy to install. While they can be an eyesore for you to look at with the filter and faucet being out in the open, companies are constantly trying to minimize the size to avoid these things.

Overall, the under-sink filtration systems are more preferred than a countertop water filter system. Countertop systems usually only have one or two filtration stages. This is okay for a few common household contaminants, but not nearly as many as you will get from an under-sink system.

The other reason why I like under-sink systems more than is something we’ve discussed already. I do not like having a filter on top of my kitchen sink; they can be bulky and are not pleasant to look at. Overall, the better the filtering qualities and the sleeker designs make the under-sink option far more popular


How often should I change my under-sink filter?

This entirely depends on the filtering system you choose. Many are rated to handle a certain number of gallons before needing to be changed. This information is provided by each manufacturer and is something you should investigate before choosing an under-sink filter.

How long do under sink water filters last?

If you are keeping up with the filter changing routinely, the actual systems will last for many years. If you forget to swap out your filters, you run the risk of contaminant build-up that can hurt your water filtering system.

Can under sink water filters remove chemicals from water?

You bet they can! Each filtering system has several contaminants that will be removed from your water. Make sure you find the one that works best for your water supply!

Do under-sink filters wastewater?

Yes, and no. Standard and conventional filters do not waste any water because they are directly connected to the waterline. RO systems will require there to be excess water due to the process of cleaning the water via a reverse osmosis filter. Some RO filter systems will use produce less wastewater than others.


In conclusion, an under sink water filter system can provide numerous benefits to you and your family’s water supply. They are a cheaper and effective alternative to whole-home water filtration systems and usually require much less maintenance as well.

While deciding on which under sink filter is best for your home, make you consider all the information from our buying guide. These points are all very important things to consider. We sincerely thank you for viewing our guide, and we are confident the best under-counter water filter for you is hiding in here somewhere!

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *