Best Under Sink Water Filter

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Best Under Sink Water Filter

If you take more than two gallons of drinking water, you’ll probably be happier after installing an under-sink water filter system in your kitchen. Maybe it’s the water’s odor and funny tastes that make you consume less than what you prefer. A high-quality under-sink water filter will remove nearly all city water contaminants to give you pure, ready-to-drink water. 

These filters are the best when it comes to on-demand applications since they connect directly to your kitchen faucets. Moreover, most of them have multiple applications, including vacation and office use. You only need to attach the filter to a big water bottle, and you’re good to go. 

We reviewed seven products based on under-sink water filter models with the highest positive reviews and direct recommendations from trusted partners. We spent more than 30 hours on each product, counterchecking the manufacturer’s information, user experiences, and various alternatives. We then tested all the products before shortlisting the ones that made it to our best underwater filter review. 

We found Aquasana AQ-5200.62 Undersink Water Filter System to be the best product overall, thanks to its innovative Claryum ® filtration technology. It removes up to 99.99% of 77 prevalent contaminants in municipal water. iSpring CU-A4 High Capacity Premium Undersink Drinking Water System is the best runner-up product on our list. It is easy to install, and it comes with the first set of filters. Other under-sink water filters in our list include the best budget product, the best quality, the best value, the best faucet, and the best easy-to-install product.

Best Under Sink Water Filter Products

  1. Aquasana AQ-5200.62 Under sink Water Filter System– Best Overall
  2. iSpring CU-A4 High Capacity Premium Under sink Drinking Water System– Best Runner Up
  3. Waterdrop 10UA Under sink Water Filter System– Best Budget
  4. APEC WFS- 1000 Super Capacity Premium Under sink Water Filter System– Best Quality
  5. Frizzlife Under sink Water Filter System– Best Value
  6. AO Smith Under sink Clean Water Faucet Filter– Best Faucet
  7. Clearly Filtered Under the Sink Water Filter System– Best Easy Installation

Best Under Sink Water Filter Reviews

1. Aquasana AQ-5200.62 Undersink Water Filter System

Aquasana AQ-5200.62 Undersink Water Filter System is the best product overall in our review list. It comes with intelligent, inbuilt technology that reminds you every time your system requires a filter replacement. This system makes the only product with P437-certified (PFOA and PFOS) filters. A single filter has up to 10x the lifespan of an ordinary filtration media.

Forget about brands that force you to pick a single-colored system, even if it doesn’t match your kitchen wall colors. Aquasana AQ-5200.62 comes in multiple finishes to give you variety. You can choose up to three different finishes that match your aesthetic preferences and interior décor or existing faucet.

Aquasana AQ-5200.62 Water Filter Review

This product is 100% lead-free and doesn’t introduce any harmful chemicals to your drinking water; neither does it waste any water during the filtration process. You’re looking at a product that filters all harmful contaminants but still retains the naturally existing minerals in water such as magnesium, potassium, and calcium.


  • Warranty – One-year limited warranty
  • Filtration Type – Claryum® filtration technology
  • Filter Life (Till replacement) – Six months
  • Filter Stages – 2
  • Capacity – 500 gallons
  • Certifications – NSF standards 42, 53 certified
  • Micron Rating – 0.5


  • Superior filtration technology
  • Easy to install, use, and maintain
  • The package includes the first set of filters


  • It doesn’t filter viruses
  • It is relatively expensive

2. iSpring CU-A4 High Capacity Premium Undersink Drinking Water System

The best runner-up product in our review list also offers the same aesthetic appeal as the best overall product. iSpring CU-A4 High Capacity Premium Undersink Drinking Water System comes in a stylish chrome finish. The faucet will add beauty to your kitchen décor without creating a distraction. It is easy to clean, enhancing its pristineness beyond the expected lifespan.

This product has a superior ultrafiltration system that removes up to 99.99% of prevalent tap water contaminants. We found it effective in improving water taste by reducing fluoride, chlorine, and chloramine concentrations.

iSpring CU-A4 Water Filter Review

It is also a go-to option if you’re dealing with heavy organic pollution such as pesticides and herbicides.

You’ll enjoy safe, ready-to-drink water that passes through four filtration stages. The first stage has a 5.0-rated sediment filter medium that removes larger contaminants such as dirt, rust, and sand. The last step contains an ultrafiltration filter media with a micron rating of 0.01 to remove heavy metals. These contaminants may include lead, copper, and arsenic.


  • Warranty – One year manufacturer warranty
  • Filtration Type – KDF ultrafiltration
  • Filter Life (Till replacement) – Six months
  • Filter Stages – 4
  • Capacity – N/A
  • Certifications – Certified frustration-free
  • Micron Rating – 0.001


  • Certified frustration-free
  • It is effective in asbestos and lead reduction
  • Easy installation and maintenance


  • It is relatively costly
  • It doesn’t lower the TDS value

3. Waterdrop 10UA Undersink Water Filter System

Do you want an endless supply of pure, ready-to-drink water without breaking the bank? Waterdrop 10UA under sink water filter system sounds like your best option in our review list. It features the most affordable price tag, which doesn’t affect its longevity and efficiency. It is among the few market products that surpass the standard six-month longevity. The filter media in this system can last up to a year without replacement, depending on your water conditions.

This water filter system comes with a high flow rate making it ideal for multiple applications. For instance, you can use it to access clean water for cooking, drinking, and washing vegetables or utensils in the kitchen. You can also use it in the bathroom to get instant filtered water. Are you going camping or on vacation? You can quickly attach this product to a bulky water bottle for outdoor use.

Waterdrop 10UA Water Filter Review

Another feature that stands out in this product is the ability to retain essential water minerals after filtration. It removes all prevalent piped water pollutants such as chlorine, odor, and heavy metals without interfering with the calcium, sodium, and magnesium mineral concentrations.


  • Warranty – Limited warranty
  • Filtration Type – Two-stage multi filtration
  • Filter Life (Till replacement) – 6 to 12 months
  • Filter Stages – 2
  • Capacity – 8,000 gallons
  • Certifications – NSF/ANSI 42 certified
  • Micron Rating – 


  • Steady flow rates and multiple uses
  • Quick installation process
  • Ultra-long service life


  • It doesn’t come with a female threaded connector
  • It may not last as long as noted by the manufacturer

4. APEC WFS- 1000 Super Capacity Premium Undersink Water Filter System

You can buy APEC WFS 1000 Super Capacity Premium Undersink Water Filter if you’re looking for a high-quality system designed and assembled in the USA. The manufacturing process of this under-sink water filter has longevity in mind. It will likely last beyond its lifespan to reflect the value of every dollar you spend on it. It is the best quality product on our review list. The filtration media lasts for slightly more than 12 months.

This product comes with a one-year warranty, tied with a satisfaction guarantee within the same period. This covers quality issues that may originate from the supply or manufacturing lines. This three-stage water filter has an easy installation process. We installed this under-sink water filter in about 15 minutes and didn’t require a tank to function optimally. That means it is also ideal for small kitchen spaces.

APEC WFS-1000 Water Filter Review

You’re looking at an eco-friendly water system that doesn’t waste resources. It removes nearly all city water contaminants but still retains naturally occurring chemicals such as calcium and magnesium. We knew from the first test that you can never go wrong with this system for long-term, heavy-duty applications.


  • Warranty – One year limited warranty
  • Filtration Type – Premium extruded carbon block filtration
  • Filter Life (Till replacement) – 6 to 12 months
  • Filter Stages – 3
  • Capacity – N/A
  • Certifications – NSF, WQA-certified
  • Micron Rating – 0.5


  • 100% lead-free chrome faucet
  • Steady feed water pressure of about 20-85 psi
  • Premium long-lasting filters


  • It is not ideal for TDS removal
  • It doesn’t filter viruses and pathogenic bacteria

5. Frizzlife Undersink Water Filter System

Frizzlife Undersink Water Filter System made it to our list as the best value product. While it is relatively costly than other products on our review list, it puts every dollar you spend on it into use. For instance, it filters up to 99% of prevalent contaminants in well and tap water without removing the naturally existing minerals. That means you get to enjoy safe, pure water with the right concentration of minerals such as calcium and magnesium.

We installed this filter in about five minutes, but it may take you up to 30 since installation isn’t something you do daily. This product features a twist-installation design that also gives you an easy time during cartridge replacement. Moreover, this water filter readily connects 3/8” and ½” feedwater valves. You don’t need to change your existing faucet.

Frizzlife Water Filter Review

This product comes with an inbuilt plastic container that houses the filter cartridge. That means you can save resources because you only need to replace the filter cartridge as a part and not the whole system as a whole. Besides, this product is ideal for multiple uses, including ice maker and refrigerator applications.


  • Warranty – Limited warranty
  • Filtration Type – Carbon block filter cartridge
  • Filter Life (Till replacement) – six months
  • Filter Stages – 2
  • Capacity – N/A
  • Certifications – NSF/ANSI 53 and 42 certified
  • Micron Rating – 5


  • It is the best value product on our list
  • It removes 99.99% of contaminants
  • A high-capacity water filter system


  • Two filtration stages
  • It may not remove viruses and pathogenic bacteria

6. AO Smith Undersink Clean Water Faucet Filter

AO Smith Undersink Clean Water Faucet Filter sounds like one of the best options that give you clean, on-demand drinking water with steady flow rates of up to 0.5 gallons per minute. The filter media in this product comes with a lifespan of about six months. However, you might have to change the filter media once you notice a decreased flow rate or when you hit the 500-gallon mark. Whichever comes first, 500 gallons or six months of usage signals a replacement.

This water filter purifies your water in four stages to remove and reduce up to 99% of 77 harmful contaminants found in municipal piped water. The first stage features an activated carbon filter that eliminates herbicides, pesticides, and pharmaceuticals.

AO Smith Under Sink Water Filter Review

The second stage features a catalytic carbon that targets chlorine and chloramines, while the third iron-exchange stage removes heavy metals such as lead and mercury. The last step removes resistant cysts, thanks to the absolute sub-micron mechanical filtration process.


  • Warranty – Limited warranty
  • Filtration Type – Claryum® Filtration Technology
  • Filter Life (Till replacement) – Six months
  • Filter Stages – 1
  • Capacity – 500 gallons
  • Certifications – NSF/ANSI Standards 42, 43, and 401
  • Micron Rating – 5


  • It comes with one lithium metal battery
  • It features innovative Claryum® technology
  • Steady flow rates of 0.5 gallons per minute


  • This product requires a battery for use
  • It is relatively costly

7. ClearlyFiltered Under the Sink Water Filter System

Lastly, you might consider this product if you want the best filter with a quick installation process. You can install this product in about 15 minutes, but our technicians did it in a record three minutes, using a wrench and a screwdriver. Moreover, this product doesn’t require permanent installation, making it a go-to filter for renters and students in hostels.

ClearlyFiltered Under the Sink Water Filter System filters your water in three stages to eliminate all toxins and pollutants. The first stage features a granulated coconut carbon priming filter that removes odors, cloudiness, colors, and chlorine taste. The second filtration stage removes up to 99.99% of heavy metals and organic contaminants such as herbicides and pesticides.

Clearly Filtered Water filter Review

If you need a water filter that removes fluoride without using reverse osmosis technology, here you have it. This product leverages the latest fluoride-removal technology to filter up to 99.5% of fluoride in its third filtration stage.


  • Warranty – Lifetime guarantee
  • Filtration Type – Premium Carbon Filter
  • Filter Life (Till replacement) – 2,000 gallons
  • Filter Stages – 3
  • Capacity – 2,000 gallons
  • Certifications – NSF-listed
  • Micron Rating – 0.5


  • Made in the USA
  • 30-day worry-free trial
  • Quick installation process


  • Unclear certificate information
  • The three filters require the same replacement

What is an Undersink Water Filter?

Unlike other water filter products, under-sink is point-of-use (POU), meaning you install it where you want access to clean, ready-to-drink water. An under-sink water filter product will serve you on-demand, especially if you have a small household that utilizes about three to five gallons of drinking water. 

That means most of these filters will work well for you if you’re about two or three people in your home. Even so, there are still premium, high-capacity options that can work well in a big household of up to six or eight people. 

What’s the filtration process of a typical under-sink water filter system? You can connect an under-sink water filter to your cold water line using a flexible tube. Some products will come with this tube, while other brands may require you to purchase it separately. The filter’s faucet experiences constant pressure that allows water out once you turn it on. 

Some filters may come with an inbuilt pressure system for faster flow rates. Kindly note that the water coming through the system’s faucet is the only clean, safe, and filtered drinking water.

Advantages of Under Sink Water Filters

Undersink water filters have various advantages than standard products, including:

  • They enhance the taste and purity of drinking water
  • Undersink water filters are relatively easy to install and replace
  • They are cost-efficient in the long haul (few maintenance needs)
  • These filters are available in a wide variety of sizes and models
  • Their installation doesn’t require additional kitchen space
  • The enhance healthy development in kids and the whole family
  • Most options are relatively affordable in terms of the initial cost

Disadvantages of Under Sink Water Filters

  • They filter water at a single point of use only
  • You’ll need a water filter tap for installation

Undersink Vs. Countertop Water Filters

Many homeowners often find themselves in a challenging situation when choosing between under-sink and countertop water filters. While all these two products will give you clean, better-tasting drinking water, they cater to specific needs and preferences. 

For instance, getting a countertop water filter sounds like the best plan if you want to maximize space. They are relatively smaller than under-sink water filters. A countertop water filter also proves to be efficient when you’re alone or about two in a household. 

Undersink water filters are a go-to option if you’re dealing with heavy pollutants, especially if you get one powered by reverse osmosis filtration technology. They will also be ideal if you want an unlimited supply of ready-to-drink water, even during on-demand moments.

Buying Guide for the Best Under Sink Water Filter

You might want to have the following considerations before settling on the best brand or model of under-sink water filter:


Price is purely aesthetic as homeowners have varying budgets for home appliances and systems. Most of the under-sink water filter systems featured in our list have relatively affordable price tags. However, you may have to pay more if you prefer aesthetics to standard functionality. Filter systems with sleek designs and high-quality finishing cost more than regular products.

Filtration Target

Every water filter system has its filtration capabilities. Most will give you better-tasting drinking water but vary with the contaminants they remove. For instance, an under-sink water filter system with reverse osmosis (RO) filtration technology is ideal for removing TDS contaminants. Similarly, a carbon block filter media will be suitable if you’re dealing with excess fluoride, chlorine, and chloramines. Thus, know the type of water and contaminants that you’re dealing with in your area. Also, well water may contain different contaminants from municipal water. Hence, you may need to use other filter systems in either case.

Discounts and Same Day Shipping

All the water filter systems in our review list are available in online stores and the official manufacturer websites. You would want to watch out for seasons that come with crazy discounts. Some manufacturers will also have all-year-around deals if you purchase via a referral link or check out with a coupon code. Generally, a product that ships the same day sounds better than what takes weeks.

Worry-Free/ Money-Back Guarantee

How many times did you buy a home appliance, only to realize that it doesn’t meet your expectations or isn’t what the manufacturer promised? Don’t take your chances with a brand that you find hard to trust. Watch out for products that come with a money-free or money-back guarantee to cushion you from losses of inconsistent quality aspects. 

In that case, the manufacturer may choose to replace or upgrade your system to the correct specification. Others will also give a full/ partial (as per the terms or minus shipping fees) refund.

Factors to Consider Before Buying the Best Under Sink Water Filter

Even with a trusted review like this one, it can still prove challenging to buy the best under-sink water filter, especially when doing it for the first time. You would want a water filter that matches your needs and expectations. You would also like a system that guarantees your money’s value in the long haul. Besides pricing and brand, what other factors should you consider before buying an under-sink water filter? Consider the following:

Flow Rate

Watch out for filter systems that feature a steady flow rate to function optimally during on-demand applications. The higher the number of users, the higher the flow rate should be. For instance, a whole house water filter should have a minimum flow rate of about 25 GPM, especially if installed in high-demand endpoints.

Ease of Installation

An under-sink water filter system shouldn’t need the attention of a plumber. The installation process should be easy, whether you don’t have professional plumbing skills. Go for products with twist-installation techniques. That way, you’ll have an easy time when replacing the filter media after six months or a year.

Space and Size Needed

One of the main advantages of under-sink water filters is that they come in a great variety of sizes. You can never lack a model that matches your kitchen spacing needs. Pick a model that comes in compact hardware. Such a model will fit in a sizable space without creating a distraction. Moreover, you hardly need the space beneath your sink unless it is around a storage area.


The thumb rule for buying any machinery product or tool includes checking the warranty information. An under-sink water filter is something you intend to use daily, if not months, and it can be frustrating if it doesn’t meet your expectations. 

Choose a model that comes with clear warranty information to mitigate any quality issues that may manifest during installation or a few days into use. Most manufacturers will give you a one-year limited warranty on high-quality models, but premium brands give up to a lifetime guarantee.


Besides the initial price tag, what are the other costs of just having the water filter system in your home? You might want to consider the costs of installation and maintenance. A filter system with an easy installation process saves you a few bucks that can purchase the first set of replacement filters. Long-lasting filter media will ensure that you don’t spend a lot on replacement filters.

Micron Rating

Micron rating measures the distance between the filtration targets and the filter media. The lower the micron rating, the more you can get out of your under-sink water filter system. However, some models may have different micron-rated filter media at each filtration stage.


Certifications from independent, third-party regulators guarantee a product’s quality and efficiency to remove all the contaminants targeted by the filtration media. NSF is one of the most reputable certifications to watch out for in a water filter system. Other certifications to watch out for include ANSI, WQA, and frustration-free. 

Even so, kindly note that a product may have a certificate for specific components and not the system as a whole. In that case, the filtration medium and faucet certifications matter the most.

Water Minerals

Water has vital mineral elements that occur naturally. These minerals are ideal for maintaining optimal body health. For instance, minerals like calcium and magnesium help to form strong bones in children. Some filters come with a small micron rating that removes these minerals alongside the contaminants. 

In that case, you would want to buy a system that retains the minerals throughout all the filtration stages or comes with mineral bags to replace the filtered minerals.

The Bottom Line

Besides quenching your thirst, water is the basis of all chemical processes in the body cells. Contaminated water may contain toxins that interfere with these natural processes. Pollutants may also alter the water’s pH, increasing the body’s acidity to dangerous levels. Get your family our best under sink water filter and start your safe drinking water journey. 

All the products featured in our review list are pretty forthcoming in quality and efficiency. Even though each product is unique to zero down needs, taste, and aesthetic preference. For instance, you can choose a chrome faucet if you’re after blending the interior décor. You can purchase any of these products from Amazon or the official manufacturer websites.

The H2Home Lab team is dedicated to helping you find the best solutions to your specific water needs, as well as provide troubleshooting tips and guides for water filtration, heating, softening and plumbing. We hope you will find the info you need on our site from any one of our buying guides or subject matter articles.