Best Under Sink Water Filter of 2021 – Complete Buying Guide & Reviews

Best under sink water filter Reviews - complete buying guide

Have you been tired of those plastic water bottles piling up and calling you for a visit to the recycling unit? We have got the ultimate solution for you. You have to get the best under sink water filter that fulfils your needs. You will surely get safe, hygienic, clean, and purified water in the comfort of your home.

Under-sink filters are designed to remove contaminants from water that are harmful to human consumption. These filters have special membranes that block the pollutants before the water reaches your tap. You can easily install them under your sink, keeping them out of anyone’s sight.

best under sink water filter for municipal and well water
Best Under Sink Water Filter

Best Under Sink Water Filter Options for Healthier Water

Water is essential for life, but it isn’t always safe. Here are the best under sink water filter options to guarantee that you and your family can drink fresh clean water without worry of impurities or bacteria sneaking in during any stage of use.

Best Rated RO Water Filter
I-Spring RCC7, 5-Stage Reverse Osmosis System
I-Spring RCC7, 5-Stage Reverse Osmosis System
  • Features: 75 Gallons, 15 x 8 x 18 inches, Faucet and mounting bracket, 20 Pounds, Reverse Osmosis
  • Benefits: reverse osmosis, good for hard water
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Best Filter for Well Water
iSpring RCC7AK 6-Stage Reverse Osmosis
iSpring RCC7AK 6-Stage Reverse Osmosis
  • Features: 75 Gallons, 15 x 8 x 18 inches, and RO System, Brushed Nickel Faucet and Storage Tank
  • Benefits: Reverse Osmosis, Alkaline
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Best Value for Money
Home Master TMHP HydroPerfection
Home Master TMHP HydroPerfection
  • Features: 5 x 15 x 16 inches, Fully assembled RO system with filters, Fast Flow RO kit and 18.75 Pounds
  • Benefits: Reverse Osmosis, Ultraviolet
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Best Drinking Water Filter
3M Aqua-Pure AP-DWS1000
3M Aqua-Pure AP-DWS1000
  • Features: 625 Gallons, 15.75 x 10.88 x 3.25 inches, water filter, and 5 pounds
  • Benefits: Carbon block
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Best affordable Under Sink Water Filter
Aquasana AQ-5300 3-Stage
Aquasana AQ-5300 3-Stage
  • Features: 600 Gallons, 12 x 4.25 x 9 inches,installation kit and 6 Pounds
  • Benefits: water filter removes contaminants like chlorine, lead, PFOA/PFOS, and others.
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High Capacity and Easy Installation
Waterdrop 15UA Under Sink Water Filter
Waterdrop 15UA Under Sink Water Filter
  • Features: 16000 Gallons, 3.6 x 3.9 x 16.7 inches, and 3.94 Pounds
  • Benefits: Three Stage Filtration and high capacity filter
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Budget Friendly Under Sink Filter
Culligan US 4 EZ-Change
Culligan US 4 EZ-Change
  • Features: 500 Gallons, 14.25 x 9.25 x 8.4 inches, and 4.16 Pounds
  • Benefits: premium filter
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Best Super Capacity Filter
APEC WFS-1000, 3 Stage Under Sink Water Filter
APEC WFS-1000, 3 Stage Under Sink Water Filter
  • Features: 6 x 15 x 12 inches, WFS-1000, and 14 pounds
  • Benefits: 3 Stage Under-Sink Water Filter
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Best Water Purifier
CuZn UC-200, 50K Ultra High Capacity
CuZn UC-200, 50K Ultra High Capacity
  • Features: 4.5 x 4.5 x 15 inches, Stainless Steel Connection Hose, and 8 pounds
  • Benefits: KDF-55 Filter Media, Catalytic Carbon Filter Media & Micro Sediment Membranes
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Best Drinking Water Filter Under Sink
3US-PS01 Filtrete Advanced Quick Change Water filter
3US-PS01 Filtrete Advanced Quick Change Water filter
  • Features: 4 x 6.8 x 14 inches, Reduces 0.5 Microns Sediment and Chlorine, and 2.75 pounds
  • Benefits: Reduces Chlorine, Reduces Microbial Cysts
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Reading: Top 10 Quality Stainless Steel Sinks of 2021 Reviews

Top 10 Under Sink Water Filter Reviews – Affordable Under Sink Water Filters

While looking to buy an under sink water filter, you don’t need to consider those hundreds of models. We are here to help you skip this lengthy and overwhelming process.

So for your convenience, we have picked out and reviewed the best under sink water filters available in the market that are good for the money and high in quality. Our buyer’s guide will help you choose the right model suitable for you, your home, and your budget.

1. I-Spring RCC7, 5-Stage Reverse Osmosis Drinking Filtration System and Ultimate Water Softener – Best Rated RO Water Filter

best under the sink water filter

This top-notch under sink water filter works wonders at a great price. If you are searching for something economical with great quality and the best filtration features, we would recommend this one for you.

The filtration process in this under sink water filter comprises 5 stages and virtually removes about 1000 contaminants from water. As a result, the water that it leaves for you is pure, clean, and tastes great.

This iSpring water filter is best rated to remove 99.99% impurities present in municipal and well water. Yes, you have got it right! This product also filters well water and turns it into soft water free of sodium and other contaminants, including lead, chlorine, arsenic, asbestos, fluoride, calcium, and more.

The components of this under sink water filter have the highest quality, thereby increasing the lifespan of your investment. The faucet is made up of brushed nickel.

Regarding the installation procedure, you can easily install this water filter under your kitchen sink, with all parts included, by taking the help of well-organized videos and instructions.


  • Capacity: 75 Gallons
  • Dimensions (L x W x H): 15 x 8 x 18 inches
  • Included Components: Faucet and mounting bracket, housings, filters, parts and tubings
  • Weight: 20 Pounds
  • Purification Method: Reverse Osmosis


  • Clear See-through 1st stage of water filter, that helps to inspect the filter.
  • Highly reliable
  • Requires low maintenance in the long run
  • Easy to install


  • The faucet delivers a slow flow of water
  • Causes water leaks if push tubing is not inserted 1/2inch deep into quick fitting connectors.
  • Produces slightly acidic water with a pH of 7.0 or below

2. iSpring RCC7AK 6-Stage Reverse Osmosis – Best Under Sink Water Filter for Well Water

best under sink water filter for well water

This under sink water filter from iSpring is a much advanced and better version of the 5 stage iSpring water filter. This product is specifically designed for the alkalinization of purified water. The filtration process in this unit involves 6 stages, where the first 5 involve the removal of contaminants and the 6th one serves to add healthy minerals for balanced alkalinity.

The filtration process removes about 1000 contaminants such as chlorine, sodium, lead(98%), arsenic, calcium asbestos, etc. The package includes a stylish European-style faucet with a high spout.

RO filter removes the ultrafine particles down to 0.0001 microns, whereas the GAC filter does the final polishing to the purified water. Finally, the AK filter restores the alkalinity of water. The resulting water you get is clean and pure and gives you health benefits with its high quality.

The brand offers video-based instructions for installation so that you can get the job done by yourself. Moreover, you can also call for their technical support whenever required.


  • Capacity: 75 Gallons
  • Dimensions (L x W x H): 15 x 8 x 18 inches
  • Included Components: RO System, Brushed Nickel Faucet and Storage Tank
  • Purification Method: Reverse Osmosis, Alkaline


  • You get mineral water at home
  • Value for Money
  • Transparent 1st stage filter that helps you know when the filter needs to be changed
  • Phone support


  • Packaging is a bit heavy
  • Needs professional installation for better results.

3. Home Master TMHP HydroPerfection Undersink Water Filter System – Best Value for Money

This HydroPerfection under sink reverse osmosis water filter is the perfect choice for health-conscious people. This water filter is built with exceptional features. Highly effective catalytic carbon filtration filters chemicals like pesticides, herbicides, chlorine, and chloramines.

 This filter purifies tap water under 9-stages of filtration, purification, and enhancement, thus removing up to 99% of iron, hydrogen sulfide, chloramines, chlorine, TDS, fluoride, chemicals, heavy metals, microplastics, pharmaceuticals, and many more. Moreover, this water filter will ensure the removal of 1000+ contaminants from your water and uses ultraviolet radiation to sterilize water, destroying all types of viruses, bacteria, and other microorganisms. The main advantage is that the HomeMaster under sink water filter does this job without delivering hot water to your faucet.

Having this under sink filter at your home, you will not need to buy those mineral water bottles anymore. This filter delivers purified water after adding balanced and healthy amounts of calcium, magnesium, and other required minerals to your water. Whether you need to purify well water or municipal water, this sink is the best choice for you.

The electric non-permeate pump ensures a fast flow of water and helps to reduce wastage of water during periods of inactivity. The delivered water is not only refreshingly healthy for you but also tastes great!


  • Dimensions (L x W x H): 5 x 15 x 16 inches
  • Included Components: Fully assembled RO system w/ filters, Fast Flow RO! kit, permeate pump, hardware
  • Weight: 18.75 Pounds
  • Purification Method: Reverse Osmosis, Ultraviolet


  • High water flow rate
  • Uses UV technology to sterilize water
  • Five-year warranty
  • Delivers mineral water on tap
  • Technical support


  • Wastes 1-gallon water per 1 gallon of purified water
  • DIY installation is a bit difficult

4. 3M Aqua-Pure AP-DWS1000 – Best Drinking Water Filter under Sink

best under sink water filter system

AquaPure under sink water filter purifies water with its two-stage carbon-block filtration. The advanced filtration process in this water filter involves the removal of chlorine, turbidity, lead, volatile organic compounds (VOCs), parasitic protozoan cysts, and other contaminants.

You do not need to worry about cartridge changes with this under sink water filter, as it automatically shuts off after 625 gallons (2366litres ) of water filtration, with its special automatic shut-off feature.

Furthermore, the AquaPure under sink water filter package also provides a chrome water faucet that delivers a good flow of filtered water. The easy cartridge changing feature in this water filter will help you to change cartridges without much effort.

As for installing the filter; the faucet, pipe connections, and installation hardware are included in the package to install it under your kitchen sink, on the primary cold water line.


  • Capacity: 625 Gallons
  • Dimensions (L x W x H): 15.75 x 10.88 x 3.25 inches
  • Included Components: Water filter
  • Weight: 5 Pounds
  • Purification Method: Carbon Block


  • Wastes less water
  • Does not require a large reservoir tank
  • Good water flow rate


  • Installation instructions are unclear
  • Low-quality connectors
  • Higher cost per gallon than other RO Filtration systems

5. Aquasana AQ-5300 3-Stage Kitchen Counter Claryum Filtration – Best affordable Under Sink Water Filter

best water filter system under sink

This water filter is also a good option for you to consider if you have a low budget. It removes 99% of contaminants from water, thereby leaving healthy minerals behind. The water you get is pure, healthy with a great flavor.

Aquasana under sink water filter removes contaminants like chlorine, lead, PFOA/PFOS, and others. The filter system is NSF certified, so you don’t need to worry about the quality standards of this water filter.

Regarding the filter’s efficiency, you will not have to wait too long for clean water; this under sink water filter powers through half a gallon of water every minute. Moreover, it will cost you just 10 cents per gallon of water.

You will have to replace the filter cartridge every 6 months/600 gallons of water.

As for the installation, the filter package includes the best quality components and the first set of filters that you can install yourself.


  • Capacity: 600 Gallons
  • Dimensions (L x W x H): 12 x 4.25 x 9 inches
  • Included Components: Filters, housing, faucet, install kit
  • Weight: 6 Pounds
  • Purification Method: water filter removes contaminants like chlorine, lead, PFOA/PFOS, and others.


  • NSF certified
  • Value for Money
  • Cost-efficient
  • Easy installation


  • Does not remove Total Dissolved Solids(TDS)
  • O-rings cannot be replaced if broken
  • Does not remove fluoride from water

6. Waterdrop 15UA Under Sink Water Filter – High Capacity and Easy Installation

best rated under sink water filter

This waterdrop filter will transform your ordinary tap water into clean and pure drinking water through its innovative multi-stage filtration process. The purified water from this under sink filter has reduced chlorine, chemical pollutants, heavy metals, sediment, and other large particles.

In addition to this, the lead-free quality materials used in constructing this filter make it durable and safe to use. The filter is NSF certified and meets all quality standards for water filtration. Advanced filter media and carbon block filtration will make your water sparkling clean while working efficiently.

The ultra-long service of this filter is truly admirable. You can easily get a service life of 24 months(16000 gallons) of water before replacing the filter if used with municipal water.

As far as the flow rate is concerned, the filter produces pure water with a flow rate of 0.75 Gpm at 60 psi. The delivered water has a pleasant taste.

Furthermore, this excellent water filter can be easily installed under your kitchen sink in a few minutes(It must be attached to a cold water line). Correspondingly, the easy twist-and-lock design helps to remove the filter for replacement instantly.


  • Capacity: 16000 Gallons
  • Dimensions (L x W x H): 3.6 x 3.9 x 16.7 inches
  • Included Components: Waterdrop Undersink Water Filtration System×1 ·Inlet hose×1 ·Outlet hose×1 ·3/8’’–1/2’’ Convertor set×1 ·Self-tapping screws×2 ·Teflon tape×1 ·Drilling sticker×1
  • Weight: 3.94 Pounds
  • Purification Method: Three Stage Filtration


  • Cost-effective
  • Simple Installation
  • Fast water flow
  • Long service life
  • Easy filter replacement


  • Does not filter well water
  • Do not remove TDS from water.

7. Culligan US 4 EZ-Change Sink Drinking Water Filtration – Budget Friendly Under Sink Filter

best drinking water filter under sink

You can also opt for the Culligan Under sink water filter if you are searching for a low-price option. This amazing filter will produce clean and great-tasting water for you and your family. This product from Culligan is less expensive and an effective water filter for cleaning tap water.

Undoubtedly, the filter’s NSF certification makes it a safe under sink filter that aesthetically reduces turbidity chlorine, chloramines, particulates of class 1, lead, cysts, mercury, VOC’s, and MTBE from municipal water.

You can easily rely on each filter for up to 6 months/500 gallons of water, after which the filter needs to be replaced. This Culligan filter delivers a water flow rate of 0.5 GPM through its dedicated faucet.

This economical under sink water filter package includes a faucet, installation hardware, 1 cartridge for filter replacement, and tubing.

For a further note, this under sink water filter is easy to install under your sink, with its quick connect fittings. The filter cartridge is also easy to replace with a twist-on and twist-off mechanism. Moreover, you do not need to switch off your water supply for changing filters.


  • Capacity: 500 Gallons
  • Dimensions (L x W x H): 14.25 x 9.25 x 8.4 inches
  • Included Components: Plumbing Fixtures, Other Faucets, utility-sinks
  • Weight: 4.16 Pounds
  • Purification Method: premium filter


  • Reasonable price
  • Easy filter changings
  • Dedicated faucet included in the package
  • Great tasting water


  • The instruction manual is not clear
  • Insufficient hardware to install
  • Slow flow of water

8. APEC WFS-1000, 3 Stage Under Sink Water Filter System – Best Super Capacity Filter

best rated under sink water filter

This greatly designed under sink water filter is also one of the best options available. It purifies water from chemicals and odor with its truly exceptional quality filters. The filter features a 3 stage filtration process to reliably transform tap water as well as well water into its clean and pure form.

In its first filtration stage, this USA assembled ApEC under sink water filter will remove dust, particles, and sediments from your water through its sediment filter. The second stage involves the reduction of chlorine, odors, colors, and turbidity. In contrast, the 3rd carbon block filter removes further chlorine, turbidity, and other chemicals.

The filter system from APEC also features a lead-free chrome faucet. Super capacity filters are not only efficient but also easy to replace. The company offers a 1-year guarantee of its product, with lifetime support.


  • Dimensions (L x W x H): 6 x 15 x 12 inches
  • Included Components: WFS-1000
  • Weight: 14 Pounds
  • Purification Method: 3 Stage Under-Sink Water Filter


  • Super capacity filters
  • No tank needed
  • Does not wastewater
  • Easy installation
  • Fast water flow


  • Does not remove copper from water
  • Does not remove fluoride or lead
  • Not good for hard water

9. CuZn UC-200, 50K Ultra High Capacity – Best Water Purifier

the best under sink water filter

For those looking for a highly rated product with the best reviews, we have picked CuZn under sink water filter. This filter has proved to be one of the best under sink water filters through its exceptional quality, reasonable price, and excellent features. It aims to purify water without reducing its mineral content, thereby not reducing TDS from water.

The micro sediment membranes and carbon block filtration remove water pollutants in a 3 stage process. Furthermore, the filter satisfies NSF standards to reduces sediments, algae, molds, chlorine, odors, water-soluble cation heavy metals i.e. lead, mercury, cadmium, chromium VI, etc., herbicides, bad taste, and many more undesirable contaminants. The resulting water is purified, healthy and safe for drinking or cooking use.

The filter company brags a 5-year warranty for the product. Installation of the system involves a direct connection to the cold water supply. You can also install the water filter yourself through video tutorials.


  • Dimensions (L x W x H): 4.5 x 4.5 x 15 inches
  • Included Components: Stainless Steel Connection Hose
  • Weight: 8 Pounds
  • Purification Method: KDF-55 Filter Media, Catalytic Carbon Filter Media & Micro Sediment Membranes


  • 5-year warranty
  • Lightweight
  • Great customer service
  • Easy setup
  • High capacity filter


  • Does not soften hard water
  • Cannot be used with well water
  • Tall unit (About 18 inches long)

10. Filtrete Advanced Under Sink Quick Change Water Filtration System 3US-PS01– Best Drinking Water Filter Under Sink

water filtration system

Here is another great option for you to consider. You can enjoy healthy drinking water by investing a little money with Filtrete under sink water filter. This awesome under sink filter will clean your tap water from rust, sand, soil, sediments, chlorine, bad taste, odours, and other microbial pollutants.

You can get purified water right at your kitchen sink without requiring to install any additional faucet. Therefore, you get the maximum flow of purified water through your existing faucet. The filter features a 6-month life before cartridge replacement. NSF certification for this filter makes it an ideal choice for safe water filtration.

For better output, you can also upgrade to this version for 99.3% removal of lead from water. Installation of this system requires a minimum of 30 minutes, as per the given guidelines. In addition to this, the filter replacement process is also very easy and quick.


  • Dimensions (L x W x H): 4 x 6.8 x 14 inches
  • Included Components: ‎Filtrete Advanced Under Sink Quick Change Water Filtration System, Easy to Install, Reduces 0.5 Microns Sediment and Chlorine Taste & Odor, Includes 6 Month Filter (3US-PS01). Manufactured by 3M.
  • Weight: 2.75 Pounds
  • Purification Method: Reduces Chlorine, Reduces Microbial Cysts


  • Maximum flow rate
  • No need of additional faucet
  • Most economical under sink water filter
  • Great flavor of water


  • Does not filter hard water
  • Does not remove copper and fluoride
  • Less durable
  • Loses water pressure with time

Buyer’s Guide for Under Sink Water Filter System – Read it Before Buying

You might be looking for an under-sink water filter that removes the most contaminants from water. That seems obvious, but it’s not as simple as it sounds. There are many other points to consider before making a purchase. We will guide you about all of them.

Also Read: How to Replace Water Filter Cartridges – Easy Steps to Do it Yourself

What Features Should You Search for When Buying an Under Sink Water Filter?

When looking for the best under sink water filter, you must look for the following features:


Firstly, you have to check the size of the water filter you need to buy. This is important because the unit has to be installed under your sink. Therefore you should have sufficient space required for fitting the new filter beneath your sink.

Filter Life

The first and foremost thing you should look at before buying is filter longevity. You might go through cheap water filter options, but they may end up being quite expensive for the reason that their filters need to be replaced every few months.

In other words, you should buy the ones that will serve you longer without the hassle of filter changes now and then, thereby increasing value for your money.

However, it would help if you always kept an eye on the filter cartridges while using your under sink water filter because they may not always last as long as advertised. The cartridge longevity depends on the quality of your water source; the more polluted your water is, the more you need to replace your filter’s cartridge.

Lead-free faucet

Many filter systems come with a dedicated faucet. Make sure to check if the provided faucet is high in quality and lead-free, as the presence of lead in faucets may ultimately make your water polluted by dissolving in it.

Water Pressure

Who doesn’t feel annoyed while waiting too long to get a single glass of filtered water! Yes, this is also a point to consider while choosing. Simple under sink water filters deliver high water pressure due to their great efficiency.

However, if your water source is highly contaminated, you should search for the one that purifies water most effectively, irrespective of your water pressure. This corresponds to removing contaminants for the greater time period, thereby transforming highly polluted water into healthy purified water. The fast flow rate may sometimes be problematic because some of the contaminants might pass through with the high flow without being removed.

High quality components

The quality of your filter’s components may eventually decide its lifespan and the quality of water it delivers. Always go for good quality under sink water filters that may cost you less in the long run.

Also, look for the filtration capacity of your filter, which will help you understand the filtration limit of your filter, i.e. which type of pollutants it will be able to remove from your water. Choose the one that suits best for the contaminants present in your water.


Good quality under sink water filters is always certified by reputable institutions. Therefore, always look for the certified filter by NSF, ANSI, water quality Association and others.

This is the best way to determine the quality of the filter you need to buy to know if the water filter is safe for use or not.

Easy Installation and Filter Replacement

While choosing an under sink water filter, consider the ease of installation. Most of these filters come partially assembled, thus require no professional installation. This is to save you from additional costs and wastage of time.

Under-sink filters are mostly easy to install so that you can install them yourself within few minutes. Another important feature is the easy replacement of filter cartridges. The filter cartridge should be simple to replace so that you can get the task done by yourself.

However, if you find the installation of your new sink very difficult, you can get help from online video tutorials. Never hesitate to call for customer support once you feel you cannot cope with the fitting connections.

Recommended Reading: How to Fix a Leaky Kitchen Sink – DIY Tip

Should You Buy Under Sink Filter or a Countertop Water Filter?

As a matter of fact, both these water filters mainly use activated carbon filters for purifying water. However, there are some differences that you should know before choosing one.

Under Sink Filters vs Countertop Filters

The under sink filters are more better than countertop ones for the following reasons

  1. Unlike countertop filters, these sinks do not cover any space above your counter as they are installed under your kitchen sink.
  2. They do not impact your kitchen’s interior like countertop filters, as they are out of sight.
  3. Under sink filters have a good filtration rate than countertop filters.

However, the under sink water filters ultimately take more space than countertop filters, owing to their large size. But that is still not a deal-breaker because they do not ruin your kitchen’s design by taking space on your kitchen counter.

Are Under Sink Water Filters Worth it?

This is the basic question that comes to mind whenever you get inspired by an unfamiliar product. We have got the answer for you! Just go through the following advantages and Disadvantages of under sink water filters to make the ultimate decision.

Advantages of Under Sink Water Filters

Under sink water filters come with the utmost benefits of water purification. Here is the list of their advantages:

Improve water taste

Under sink water filters remove contaminants from water using activated carbon filters, thereby delivering refreshing and pleasant water. These filters also ensure the removal of bad odors from water.

Improve water quality

The water purification from under sink filters involves the removal of:

  • Sediments: Pleated polypropylene or spun polypropylene cartridges help removing sediments from water. Though, activated carbon filters may also serve well for this purpose.
  • Chlorine: The magical power of an activated carbon filter also ensures chlorine removal from water in 1 or 2 stages.
  • Heavy metals: Many under sink water filters are designed to remove heavy metals from water, as these metals are quite unsafe in drinking water. The removal of the heavy metals takes place via an activated carbon filter or a KDF carbon filter.
  • Flouride: Although not every under sink filter removes fluoride, the filters that do this job have a special alumina filter for this purpose. However, the total amount of fluoride is not removed.
  • Arsenic: The same Alumina filter also removes arsenic from water.
  • Calcium and magnesium: Cation filters are designed for the removal of calcium and magnesium.
  • Nitrites and Nitrates: Under sink filters have a special anion filter for the removal of nitrites and nitrates that are very dangerous to consume.
  • Microorganism and Bacteria: Most of these filters have a special cartridge for blocking microorganisms and bacteria so that the delivered water is free from bacteria, viruses, and other microorganisms.

No space required on the counter

You do not need large storage space for an under sink water filter. These filters can be easily installed under your sink in a closed cabinet. You can drink filtered water from your kitchen without compromising space on your kitchen counter.

Easy DIY installation

Under sink water filters are specifically designed to install with less effort and in less time. Therefore, you can install it yourself by reading the manufacturer’s instructions or learning through DIY installation videos.

Environment friendly

Each time you buy plastic bottled water, plastic pollution rises. These filters provide you the best-filtered water at home, costing you less and providing greater benefits at the same time.


There is a great variety of under sink water filters you can choose from. You can either opt for a basic version that will filter your water from large pollutants, or you can go for a more standard version that reduces every contaminant from your water. Moreover, if you like to have more health benefits, you can also purchase the model designed for remineralization, providing mineral water at the tap.


If you go for a good quality, certified under sink filter, it will last you a good time.

Reasonable Price

Undersink water filters are available at reasonable prices, being worth every penny. These save you from bottled water purchases.

Easy Maintenance

These filters are easy to install and maintain. Their maintenance involves just cartridge replacement.

Disadvantages of Under Sink Water Filter

You have gone through the greatest benefits of under sink water filters. But wait! there are some drawbacks too. Just have a look.

Single outlet

If you need a filter that supplies clean and purified water all over your house, this is not for you. Under sink filters are meant to deliver water through a single faucet in your kitchen sink. You will have to go for a whole house water filtration system for getting clean water at every tap.

Separate faucet

This type of filter powers through a separate faucet. However, some versions also deliver clean water through your kitchen sink faucet.

Require Enough space below the sink

If you do not have sufficient space for your filter under your sink, you will have to make some modifications.

Recommended Reading: How to Remove Chemical Stains From Stainless Steel Sink

How does an Under Sink Water Filter Work – Types of Under sink Filters

You might be thinking, how does an under sink water filter work, and how does it deliver filtered water? For getting the hang of its working, you should know the two basic types of under sink water filters.

Simple Under Sink water filters

These filters are named according to their simple way of installation and delivering filtered water.

These filters are connected to the main cold water supply. All the water from the cold water line first goes through the filter, passing through various stages of filtration. After that, the filtered water is delivered to your main kitchen sink faucet. In simple words, these filters purify the water before it reaches your kitchen sink tap.

As said that, you do not need to install any additional faucet for these type of filters.


  • Less expernsive
  • Reqire no countertop or sink modification
  • No additional faucet is required
  • Easy to install


  • More water is filtered, therefore the filters requires more cartridge replacements
  • The high flow rate may contribute the presence of containments in the filtered water, as some of them may pass with the high water flow

Conventional Under Sink Water Filters

You have guessed it right! These filters are the oldest versions of under sink water filters.

Conventional under sink filters work by diverting the water from the cold water pipe to the filter system using a short, plastic pipe connection. As soon as the water is filtered, the water is sent from thes system to either a separate tank or a separate faucet installed above the kitchen sink.

This corresponds to the fact that the water reaching your filter dedicated faucet will be the one that passes through the filter. At the same time, the water that comes through your regular faucet will be unfiltered.


  • You need to less cartridge replacements because not all the water coming through the line is filtered.
  • Cause better filtration, due to the fact that water stays longer in the filter
  • Easy installation


  • Require additional faucet
  • You may have to make some modifications in order to install a dedicated faucet
  • Require flow rate of filtered water

Related: Top 11 Kitchen Sinks of 2021 with Complete Buying Guide

undersink water filter installation guide
Infographics: Undersink Water Purifier Installation Guide

How to Install Under Sink Water Filter

Under-sink filters are quite easy to install. However, you may require some basic instructions to fit them under your sink. We will guide you on how to install an under sink water filter yourself.

  • Remove the tubing

Turn off the cold water valve under your sink. Disconnect the water line from the valve by loosening the nut. Now, remove the tubing.

  • Mark the position of the new filter

Place your new filter on the cabinet wall, keeping it close to the cold water line. Mark the location of the holes in the mounting bracket. Drive screws halfway through the hole. Make sure to leave some space below the filter for changing cartridges.

  • Plumbing connections

Make sure to make all the necessary plumbing connections as shown in the instructions/video. Tighten the fittings using an adjustable wrench.

  1. Connect the filter to your sink.

Hang the filter system on the wall and tighten the screws to hold the unit firmly. Connect the supply line to the cold water valve

  • Make the final Connections

Connect another supply line to the faucet stem. Turn on the water supply. Release any trapped air using the pressure-relief button. Check for leaks, if any.

How Often Should You Change Your Under Sink Filter Cartridges?

There is no general answer to this question. The need for cartridge replacements depends on the model design and the quality of water it filters. You will need to replace your cartridge more often if your water source is highly contaminated.

Some under sink filters have an automatic system to notify whenever cartridge replacement is required.

Under Sink Water Filter Replacement – How to Change Your Filter Cartridges?

This also differs according to the model you have. However, we can provide you some basic instructions in this regard:

  1. Turn off the water supply
  2. Drain the water present in your faucet.
  3. Open the casing according to the manufacturer’s instructions.
  4. Remove the cartridge and clean the casing.
  5. Fit the new cartridge and close the casing.
  6. Turn on the water line and check for leaks.

Frequently Asked Questions (FAQ’s)

Which under sink water filter removes the most contaminants?

Reverse osmosis water filters are known to purify water from about 99 % of contaminants. These under sink filters are the most effective water filters. They remove chlorine, pesticides, insecticides, heavy metals and other chemicals, and hormones.

How do I choose an under sink water filter?

Firstly, know the type of contaminants present in your water that has to be filtered. Then choose the water filter accordingly, considering the ease of installation, required maintenance, and the need for filter replacements.

Which under sink water filter removes fluoride?

A reverse osmosis water filter is the most effective way to remove fluoride in water. Fluoride is not removed by refrigerator water filters. A home filter, such as reverse osmosis, is the most cost-effective way to get rid of fluoride in the drinking water supply.

Which under sink filter works best to remove methane and hydrogen sulfide?

Reverse osmosis systems, when combined with closed-tank aeration units, can be used to remove heavy metals and dissolved gases like Radon, Methane, Carbon dioxide, and Hydrogen Sulfide.

How much do under sink water filters cost?

The cost of installing a water filter in an under-sink area is about $150 to $1200. System installation costs $50-$1,00 for a DIY project. However, a professional can usually install the system for $100 to $300.

How long do under sink water filters last?

It depends upon the type and usage of the water filter.  Commercial filters need to be replaced every 4 to 6 months. Whereas,filters in residential settings need to be changed every 6-12 months. Reverse Osmosis, membranes, and mineralization water filters need to be replaced every 2 or 4 years, depending on the model.

Final Words

After reading this article, you should have a better understanding of how to choose the best under sink water filter for your home, farmhouse or office. From our research, we recommend the iSpring RCC7AK 6-Stage Reverse Osmosis for hard water and the Waterdrop 15UA Under Sink Water Filter unit. Both are an excellent choice if your budget allows it because of its high quality and performance that will leave you with clean filtered drinking water without any hassle from now on!

We believe that the kitchen is the heart of a home, and the sink is its centerpiece. At Best Kitchen Sinks, our team of editors and writers put their maximum efforts into consolidating buying guides and reviews that are informative, unbiased, and helpful for homeowners in choosing the best kitchen sinks and other related products for their lovely kitchen! Alex Roy is the founder of best kitchen sinks. Being an expert in kitchen renovations, he believes in designing kitchens with the perfect sinks and other appliances to make kitchen tasks easy and free of mess. Alex Roy knows first-hand the challenges homeowners and business owners face when buying the best sinks and appliances for their kitchens. Besides the honest reviews on top kitchens sinks and filters, you will also find much information regarding kitchen sinks. From installation and plumbing to cleaning the kitchen sinks and troubleshooting any sink problem, our detailed and step-by-step guides will help you maintain your kitchen sink in the perfect shape at a minimal cost.

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