Best Rated Under Sink Water Filters That Fit Under the Counter

Best Rated Under Sink Water Filters
If you’re familiar with the benefits of filtered water, then you know that buying the best under the sink water filter can be a total game changer in terms of improved health and the amount of money you’ll save each year by canceling your water delivery service.  But if you’re shopping around for a water filter system you’ll soon realize that choosing the right model for your home is a lengthy process and one that can feel a little overwhelming considering the hundreds of models available.

We’ve done all the research for you and chosen the top four models of under the sink water filters on the market. We’ve looked at their filtering processes, how much water they can filter per cartridge and we even spoke with consumers who purchased each system, in order to determine the advantages and disadvantages that you’ll run into with each model.

You’ve probably come across reverse osmosis water systems, but you’re not sure what makes them different from simple or conventional models. We’ve explained exactly how this type of system works in our article that focuses on how does reverse osmosis remove minerals, and you’ll also find more information on reverse osmosis down below in our extensive buying guide.

We hope our reviews of these leading models and our water filter buying guide will help you to choose a water filter system that’s right for your home and your budget.

Comparison  Chart

ProductTypeFilter stagesCostRating
APEC Top Tier Reverse Osmosis Drinking Water Filter System
APEC Top Tier Reverse Osmosis Drinking Water Filter System Review
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Reverse Osmosis5$$$*****
3M Aqua-Pure Under Sink Water Filtration System

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WaterChef U9000 Premium Under-Sink Water Filtration System
WaterChef U9000 Premium Under-Sink Water Filtration System Review
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iSpring RCC7AK 6-Stage Under-Sink Reverse Osmosis Drinking Water Filtration System
iSpring RCC7AK 6-Stage Reverse Osmosis Drinking Water Filtration System Review
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Reverse Osmosis6$$$*****
Culligan US-600A Drinking Water Filtration System
Culligan US-600A Drinking Water Filtration System Review
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Quick Summary

APEC Top Tier Reverse Osmosis Drinking Water Filter System:

An innovative system designed to remove more than ninety-nine percent of contaminants from tap water, this popular system can provide an endless source of pure drinking water for you and your family. However, the complicated installation process can require the services of a licensed plumber if you have no plumbing experience.

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3M Aqua-Pure Under Sink Water Filtration System:

Incredibly easy to install and maintain, you’ll enjoy an endless supply of purified drinking water via the cold-water faucet. If you’re on a tight budget or you don’t have much space to spare in the kitchen, this system is a great buy at an affordable price.

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WaterChef U9000 Premium Under-Sink Water Filtration System:

Offering a higher than average purified water capacity, brushed nickel faucet, quality components, and a lifetime warranty, this top of the line water filter system is built to last.

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iSpring RCC7AK 6-Stage Under-Sink Reverse Osmosis Drinking Water Filtration System:

A compact, powerful water filter system that can eliminate over ninety-nine percent of water contaminants, and a sixth filtration stage that ensures you’re drinking only the best tasting water, this reverse osmosis system is a total steal for the price.

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Culligan US-600A Drinking Water Filtration System:

Reasonably priced, this system is designed with easy installation in mind, but the fact that it fails in so many areas and begins to leak soon after installation tells you exactly why this system is priced so low.

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1. iSpring RCC7AK 6-Stage Reverse Osmosis Drinking Water Filtration System Review-Top Rated Under the Sink Water Filter

iSpring RCC7AK 6-Stage Reverse Osmosis Drinking Water Filtration System Review

This is a reverse osmosis system and unlike other RO systems that feature a five-stage filtration process, this model by iSpring features six stages. The system’s innovative membrane is able to remove over ninety-nine percent of water contaminants.

The alkaline remineralization filter will add important, healthy minerals, such as potassium, sodium, magnesium, and calcium, back into the water, significantly improving the taste.


This filter system can remove over a thousand different types of pollutants from your drinking water.

The system’s compact design allows it to easily fit under your sink.

Most reverse osmosis systems will use a basic calcium carbon filter to introduce ionized minerals back into the water, but this system also uses red mineral stones for this purpose.

With the purchase, you’ll get unlimited lifetime support, a one-year product warranty, and a one-year money back guarantee.


As with any standard reverse osmosis system, you can expect a lengthy and complicated installation process.

Unlike a simple of conventional water filter system, you’ll have to wait for the system’s tank to fill up with purified water, which means it’s not always readily available.


Reverse osmosis systems have a reputation for producing the purest water, and with the addition of a sixth filtering stage, you won’t doubt this system’s efficiency. Because it has a dedicated faucet, you also won’t have to worry about a drop in water pressure.

Overall, this water filter system by iSpring ensures that you’re drinking only the purest, best-tasting drinking water, without the hassle of changing out filter cartridges once a month.

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2. WaterChef U9000 Premium Under-Sink Water Filtration System Review-Higher Than Average Water Capacity

WaterChef U9000 Premium Under-Sink Water Filtration System ReviewEquipped with stainless-steel housing and a one-thousand-gallon capacity rating, this innovative water filtration system by WaterChef is a best-seller for all the right reasons. It features intelligent monitoring that prevents you from tossing out a cartridge before it needs to be replaced. Once a cartridge needs to be replaced, the LED lights on the faucet will switch on indicating a change is needed.

This system features patented big block filtration technology that’s designed to eliminate a wide range of water contaminants such as chloramine, chlorine, MTBE, trihalomethanes, benzene, and cysts.


This system is NSF certified and tested.

The pre-filter features a three-ply design for longer lasting cartridge life and improved contaminant removal.

Homeowners will also appreciate the sixty-day money back guarantee, which allows them to try out the system for two months and return it for a refund if they’re unsatisfied with its performance.

Definitely built to last, the system also comes with a lifetime product warranty, which will give buyers more confidence in their purchase.

Because the filter system has such a large water capacity, most buyers reported that the cartridge only had to be changed once a year.


Drilling is required in order to install the special faucet. We recommend having the system professionally installed if you don’t have any plumbing experience.

There were several reports that the tank began to leak almost immediately after installation, but upon further inspection, we found that this is often due to consumer error and improper installation.


For some, the system was a little on the pricey side, but once you take into consideration the low maintenance needs and ongoing costs such as cartridge replacement, you’ll find that while the initial cost is a little high, you’ll save hundreds of dollars in the long-run. Built to last, the lifetime warranty and sixty-day money back guarantee gives consumers every reason to buy.

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3. 3M Aqua-Pure Under Sink Water Filtration System Review-Best Simple Under the Sink Filter

3M Aqua-Pure Under Sink Water Filtration System ReviewThis is a three-stage, simple under the sink water filter system that features a six-thousand-gallon capacity, offering a two and a half gallon flow of purified water per minute. Because this is a simple system, there’s no drilling required and no additional faucet to install. Instead, you’ll enjoy an endless supply of purified water via the cold water from your dedicated faucet.

The manufacturer claims the filter system can remove a wide range of harmful chemicals including chlorine, lead, heavy metals, parasitic protozoan cysts, benzene, toxaphene, p-dichlorobenzene, and much more.


The filter is NSF certified

Because you don’t have to install a second faucet, the installation process is actually very fast and easy.

Unlike a reverse osmosis system, which requires its own separate tank, this system allows you to simply turn on your cold water faucet and instantly enjoy an endless flow of purified water that you can drink and cook with.


Since the purified water is flowing through your dedicated faucet you can expect a change in water pressure, although most buyers reported that the change in pressure was not significant.


This system by 3M is a great buy for any homeowner on a budget. If you don’t have any prior plumbing experience, then the fact that this system is so easy to install and maintain will be a big selling point for you. Additionally, because you don’t have to make room for another faucet, this system will work well for smaller kitchens.

While there have been reports that the water pressure can drop significantly at times, we still felt that this system was totally worth the purchase. We would recommend it to any homeowner who’s looking for a basic water filter system that won’t break the bank.

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4. APEC Top Tier Reverse Osmosis Drinking Water Filter System Review-Best Value

APEC Top Tier Reverse Osmosis Drinking Water Filter System Review

This reverse osmosis system by APEC is designed to remove up to ninety-nine percent of contaminants such as bacteria, viruses, heavy metals, fluoride, chlorine, lead, arsenic and much more.

This system comes with JG food grade tubing that’s FDA certified, a one-year product warranty, and quick connect fittings for fast and easy installation. The patented quick-connect fittings feature teeth made from stainless steel for improved grip. The included O-ring provides a leak-proof seal.

The filter system features a double carbon block design that can remove up to ninety-nine percent of chlorine chemicals, while also improving the taste of the water.


This filter system treats both well water and tap water.

APEC offers online instructional videos that help to simplify the installation process and are easy to follow.

The five-stage filtering process ensures pure, delicious drinking water that’s free from impurities and harmful chemicals.

After filtration, you’ll enjoy crystal clear, great tasting water.


This model comes with a separate faucet for purified drinking water, which means a more complicated installation process. If you have no plumbing experience, professional installation is recommended, so you’ll need to factor this additional cost into your budget.

There were numerous reports that the included plastic fittings had to be replaced immediately because they often leaked.


There was some mixed feedback regarding ease of setup. Some buyers claimed it took them as little as an hour to install, while for others, it was a complicated process that resulted in calling in a pro. Bottom line, if you have little to no plumbing experience we recommend having it professionally installed to save yourself the headache.

Overall, this RO system performs better than expected and produces great tasting water that can rival your favorite bottled brand.

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Culligan US-600A Drinking Water Filtration System Review-Buyer Beware 

Culligan US-600A Drinking Water Filtration System Review

This is a simple under the sink filter, which means it’s installed right into your main water line, so you won’t have to install an additional faucet. It comes with a D 20A filter that’s designed to remove chlorine and other impurities that can affect the taste of your drinking water. It can filter up to one thousand gallons and lasts up to one year. It’s reasonably priced and sounds great, but what the manufacturer won’t tell you is that you’re going to have to make a trip to your local hardware store to find the right fittings to prevent this filter from leaking.

While Culligan claims that their filter cartridges last an average of one year, there were many reports that the cartridge didn’t even last six months. Most users quickly realized that a cartridge needed to be replaced once large chunks of the filter started coming out in the supposedly purified drinking water.


There are many lower priced water filter systems on the market just like this one from Culligan. They’re priced low to get you to buy, but they don’t come with the right components and tend to arrive with shoddy parts that will crack or split just months down the line. The fact that these cartridges begin to disintegrate and end up in your drinking water should be more than enough reason to pass this model by.

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Under the Sink Water Filter Buying Guide

When you’re shopping around, searching for the best under the sink water filter, you’ll probably come across many models that are marketed as the best simply because they feature five or seven stage filtration, or other manufacturers will push you to buy, claiming they offer the top-selling reverse osmosis water filtration system.

Often, the more filtration stages a system offers, the higher the price tag. All filtration systems will come with at least three filters that the water will pass through before it reaches your glass. Some of the top of the line under the sink systems come with five to seven. Generally speaking, the more filters the water has to pass through, the cleaner the water will be. This is because each of the filters is designed to capture certain types of contaminants.

Just keep in mind that the seven-stage filtration systems are often very large and bulky, which can make installation a nightmare if you don’t have much space to work with under the sink.

There are also several types of filters to choose from. Most models will come with pre-filters, which are designed to remove cloudiness and sediment. They’re also usually equipped with a standard carbon-based block that will capture chlorine and other contaminants. Higher priced models will come with a UV filter or a reverse osmosis filter, both of which are said to capture more contaminants than a basic carbon filter.

When it comes to installation, installing one of these systems can be tricky if you don’t have any experience or not much space under the sink.

These filters are installed under the sink, directly into the water line. Some systems will filter all of the water that flows through the faucet, while other models will require a more heavy-duty installation that involves drilling a hole in the countertop or the deck of the sink for a separate faucet filter.

Filter Options for Conventional and Simple Water Filter Systems

Modern Filter Systems

The number of filter stages in addition to the type of filters the under the sink filter system uses will be very important. Unlike traditional reverse osmosis systems, these under the sink filters will process the water on demand, which means you won’t need a connection to a drain or a storage tank. Every drop that will go into the filter will come out as drinkable.

These systems are under constant pressure, so when you turn on the faucet, the water will quickly flow through the filter and out the faucet instantly.

For conventional under the sink filter systems, only water that’s delivered through a special faucet will be filtered. The regular hot and cold water functions usually remain independent of the filter.

Simple under the sink models will filter the cold water exclusively. The cold water will be diverted through the filter, so all off the cold water is pure and drinkable. The hot water will not be filtered. Systems that don’t require a separate faucet are more practical and are quickly gaining popularity with homeowners.

So, let’s break it down for you.

Conventional under the sink filters are more expensive and you must drill a hole in your sink or counter to accommodate the special faucet. But their filter cartridges will also last longer because you’ll only use the faucet for drinking water. Due to the reduced flow rate, higher quality drinking water is produced.

With simple under the sink filters, you don’t have to do any drilling, there’s no complicated installation and they’re also more affordable. However, because the cartridges will end up filtering all of the cold water from the faucet, even water that’s used for cooking or cleaning tasks, the cartridges need to be replaced often. Their higher flow rate also makes some of the filtration tasks less practical.

Modern Filter Systems Versus Reverse Osmosis

These days, new water filter systems can perform the type of filtration tasks that were only possible with reverse osmosis systems. But newer filter systems come packed with a wide range of filter options, each of which can affect the water’s purity in very different ways.

Here is a list of the different types of filters available:

Carbon filter: Almost all models will come with an activated carbon filter and it’s often the cornerstone of most systems. This type of filter will improve the odor and taste of the water. They’re also responsible for removing larger particles from the water, such as silt and sediment. The filter works by absorbing and attracting the large particles, removing them from the water. This type of filter can affect the way the water tastes because it reduces contaminants such as chlorine, which can make water have a sharp or bitter taste.

Reverse Osmosis: This water filter system has been popular for several years, mainly because it can remove all kinds of dangerous contaminants from the water, ensuring that your drinking water is odor-free, clear, and tastes great.

Alkaline: This type of filter utilizes a process that’s known as electrolysis. During filtration, the water passes over plates that are electrically charged. The water is then separated into two streams. One of which is acidic and the other is alkaline.

Here’s a rundown of the types of filters that are needed to remove certain types of contaminants and improve taste:

Taste: Activated carbon

Chemical reduction including chloramines: Specialty carbons that are designed for enhanced chloramine reduction.

Heavy Metals: Activated alumina with iron oxide

Fluoride: Activated alumina

Water Hardness Reduction: Cation resin

Sediment: Spun polypropylene or pleated polypropylene.

Nitrates: Anion resin that’s nitrate selective

Cryptosporidium/Giardia: Carbon block filter, sediment filter, and a ceramic filter

Increase in Ph levels: Calcite

Bacteria: Ceramic filter

To Reduce Minerals: De-ionizing cartridge

Why are Reverse Osmosis Systems So Popular?

Sink Water Filter Buying Guide

We’re going to delve a little deeper into what an RO system is, what it can do, and what makes them so popular. These systems are pretty complex and they have a reputation for producing pure, great tasting drinking water, but the sheer cost of a reverse osmosis system is enough to turn some buyers off to this option.

A reverse osmosis system uses water pressure to force the water molecules through a fine membrane that essentially removes all of the contaminants. The purified water is collected from the permeate side of the membrane, while the water that contains the concentrated amount of contaminants is forced down the drain into the contaminated side of the filter system. Most models consist of a carbon filter, chlorine and sediment pre-filter, membrane, and a storage tank.

Extensive RO Filtration Stages

Sediment: Removes large particles including rust and sand.

Carbon: Removes chemicals such as chlorine from the water. These chemicals can potentially damage the membrane if they’re not effectively removed during this stage.

RO: This stage removes anything that’s larger than a water molecule and it’s where the bulk of purification takes place.

Remineralization: Water that’s highly purified is slightly acidic. Some reverse osmosis systems will remineralize the water with magnesium and calcium in order to balance the Ph levels, introducing healthy minerals and improving the taste of the water.

Second Carbon Stage: This stage is referred to as polishing. This second carbon filter will remove any odors or taste that the reverse osmosis stage failed to pick up.

As you can see, reverse osmosis systems offer an extensive filtering process that’s designed to eliminate a wider range of harmful contaminants from the water. However, these systems are much more expensive than conventional and simple under the sink filter systems. Additionally, the installation process can be very complicated and time-consuming.

Final Thoughts

These reviews of the leading models are designed to give you a closer look at what each system has to offer while also learning more about each model’s pros and cons and how they rated with homeowners. Our goal is to provide you with all the information you need to make an informed decision when it comes time to choose an under the sink water filter that will work for you and your family.