Best Under Sink Water Filter Systems Reviews (Buying Guide)

by Curtis Grossi | Last Updated: March 19, 2024
Under-Sink Water Filters

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The best under sink water filter systems are an excellent alternative to countertop filtration systems. They are also an economical option when plumbing in a whole-house water filtration wouldn’t be possible.

In our buying guide for under-sink water filtration systems article, we explain in detail what you should look out for when purchasing an under sink filter. For those who might be in a hurry, though, let’s take you through our reviews of the best under sink water filters this year.

Are you in a hurry? If you don’t have time to read our article, then please use the links below to quickly find the best under sink water filter systems for you on Amazon.

1. iSpring RCC7AK 6-Stage Under Sink Reverse Osmosis Water Filter

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This American`s favorite model has a 3.2-gallon tank with a 2.5-gallon holding capacity and produces 75 gallons per day (GPD) enough water for a family of four. The transparent 1st stage housing will allow you easy monitoring of the filter so as to know when it`s time for a replacement. It also comes with a lead-free brushed nickel faucet.

The unequaled multi-stage complete filter pack comes with alkaline filter included and produces matchless water that is better than most bottled water. It uses the high-level RCC7AK consisting of a 6-stage filtration on reverse osmosis (RO) technology to filter over 1,000 different contaminants commonly found in municipal and well water.

This unit ticks almost all the boxes when it comes to features and performance. It has the coveted Gold Seal Certification from WQAfor top-notch removal rates and strictly complies with FDA, NSF/ANSI standard 58. Installation is made easy with instruction videos and technical help is only a phone call away for anyone who wishes to DIY.

With a 45–70 psi feed pressure, large sediments and contaminants are filtered out in the first 3 pre-filter stages using a PP sediments filter, a Carbon KDF (GAC) filter and a Carbon block (CTO) filter. These filters also protect the RO membrane from chlorine and chloramines chemicals.

Only water molecules can pass through the 0.0001 microns filter located on the main part of the unit – the RO filter. All other contaminants are blocked as the water goes from the 4th to the 5th stage where final polishing happens on the fine GAC filter. Unfortunately, the RO removes even the beneficial mineral from the water making it slightly acidic with a pH of 7.0 or less.

The best part is that this unit takes the water to a final and most important filter where all-natural red mineral stone and calcite in the 6th stage filter re-mineralize it with calcium and magnesium. This makes it more alkaline and the end result is great tasting water with a balanced pH. See also our top 10 water ionizer reviews.


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2. CuZn UC-200 Under Counter Water Filter

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The installation of this American manufactured unit requires no extra faucet; you only hook it to the cold water line, a 5 minutes process (instruction videos available). The UC-200 with a 3/8” male compression inlet/outlet fittings comes with a 36” long 3/8” by 3/8” braided stainless steel hose. With a 2 GPM flow rate, it has a capacity to filter 50,000 gallons of water (equivalent to about 5 years).

Through the micro sediments membrane, a patented combination of KDF-55 filtration media and virgin acid washed catalytic coconut shell carbon filtration media – tested to NSF standard 42 and 61, a wide variety of organic and inorganic pollutants such as heavy metals, pesticides, algae, chlorine, sediments, mold, bad taste and odor among others are all filtered out.

Important to note: since a TDS or PPM meter is not effective with this kind of filter, the UC-200 does not reduce total dissolved solids like calcium and magnesium because it`s purpose is filtration not softening. Therefore, health beneficial minerals are retained in the water.

However, the KDF-55 media reduces them so that there is no scale formation on water heating equipment like coffee makers.

A feature that makes this one of the best under sink water filters in 2019, is that unlike carbon-only filters, CuZn UC-200 uses a bacteriostatic filtration system which is not susceptible to bacteria or mold growth. In turn, the unit requires nearly no maintenance.


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3. APEC WFS-1000 3 Stage Under Sink Water Filter System

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The supreme quality APEC WFS unit uses three premium long-lasting filters to deliver a continuous supply of high-quality water for office or home.

The high-grade 10”- 100% pure polypropylene filter has a high capacity to hold sediments, rust, dirt and dust particles which means filter lifespan is lengthened and changes made fewer. These filters last over 12 months.

One great feature that our review team highly praised is that compared to resin bonded filters this system produces no waste water. This means that the set-up is also pretty easy.

In the second and third stage, high premium carbon blocks remove common chemicals among them chlorine, VOCs and others, together with bad odors/taste. Just like the CuZn UC-200 Under Counter Water Filter discussed above, this unit also does not remove TDS – totally dissolved solids. Thus, important minerals and water alkalinity is preserved.

You can depend on this American designed and assembled filter for high-quality water filtration whether you use municipal water or well water. In addition, the unit is backed by FDA certified JG food grade tubing, WQA certificate, and a 1-year satisfaction guarantee.

The APEC WFS under sink filter comes with a lead-free chrome faucet, 5 feet food grade tubing, and a ½” – 3/8” all-round adapters with a feed water pressure of 20 – 85 psi.


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4. Aquasana AQ-5300 Under Sink Water Filter

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The Aquasana 3-stage filter uses ion-exchange for its main filtration process. In the first stage, rust, sediment, and silt are caught as the water goes through the 20-micron pre-filter thereby reducing clogging.

This filter has a P473 certification to remove perfluorooctanoic acid and perfluorooctane sulfonate. VOCs such as pharmaceuticals, herbicides, pesticides, detergents, and chlorine are reduced hence improving water taste and eliminating bad odor in the second stage.

In the third and final stage, heavy metals like lead and mercury are filtered through an ion-exchange process using NSF certified claryum. 0.5 submicron mechanical filtration further eliminates asbestos and cysts while reducing chloramines.

This high-performance filtration unit has a 6-month filter lifetime and is certified by NSF to 42, 53. 401 and P473.

It boasts a 0.5-gallon per minute flow rate on a 7” high spout. You can choose one of the three (brushed nickel, chrome or bronze) designer lead-free dedicated faucet to match your home or office. All DIY parts for installation and the first set of filters are included and no waste water is produced.

There’s yet another interesting feature that qualifies it as one of the best under sink water filters for home: this model is designed to alert you (with light and sound) when a filter change is required, which is after 800 gallons or roughly 6 months. You do not need to disconnect hoses or water lines, simply twist off the filter housing and replace it with a snap.


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5. Filtrete Advanced Under Sink Water Filtration System

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There’s no way we’d have failed to include the Filtrete in these best under sink water filtration systems reviews. It’s currently one of the most popular water purification systems online and it’s also worth your attention if you are looking for an affordable model that won’t require a lot of space for installation too.

This unit reduces 0.5 micron sediments, rust, silt, microbial cysts, particulates, lead, bad odor/taste and chlorine based on 3M testing.

The filter cartridges last about 6 months or 2,000 gallons capacity whichever comes first. The system maintains water flow at 2.25 GPM flow rate on a 25–125 psi. It`s maximum, advanced and standard filters are interchangeable with the system and require an easy ¼ turn to change or replace filters.

It installs easily with an easy push-fitting connection which connects well to your existing kitchen or bathroom faucet in a three-step process. First, switch off the water and connect the supply hose to the output on your filter head. Second, attach water supply hose to the input on your filter head. Finally, attach the filter with easy ¼ turn installation then turn the water back on.

This under sink water filter is NSF certified standard 42 and 53 and comes with a 1-year limited warranty. It also comes with 5” by 3/8” tubing, 3/8” by 1/2“faucet adapter, 3/8” ferrule, 3/8” compression Hex Nut, 3/8” tube insert 2 Phillips mounting screws and one 3us-pf01 filter cartridge.


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6. iSpring RCC7 5-Stage Prestige Under Sink Reverse Osmosis Filter System

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The ISpring 5-stage prestige under sink water filter uses reverse osmosis (RO) for superior performance resulting in pure clear water that is safe from all common contaminants and has great taste. This high-quality unit will offer years of pure filtered water while requiring virtually no maintenance.

Tested and certified by WQA, all parts including the tanks, filters, and tubing are up to par with NSF/ANSI standard 58 acquiring the WQA Gold Seal certification.

The iSpring manufacturing company has a renowned reputation for having the industry`s leading customer support services. The entire system also goes through testing for leaks, cycle resistance and pressure to maintain top-notch quality and standards.

It comes with a 3.2-gallon pressurized tank, housings, 4 – ¼” color coordinated tubing, spare fittings, and O-rings. It also has a feed water adapter, a drain saddle, faucet, and a water detector.

It operates with an incoming pressure of between 45-70 psi and can produce up to 75 gallons per day (GPD) enough for a standard size family.

The multi-stage system has 3 pre-filter housings: PP sediment filter, Carbon KDF (GAC) and Carbon block (CTO) filter.

These filters remove everything from large sediment to dissolved solids, metals and chemicals while protecting the RO membrane from chlorine and chloramines.

The premium RO membrane – which is the heart of the system, removes contaminants as tiny as 0.0001 microns. Then the water molecules that squeeze in through the membrane are taken through a fine GAC filter for ultimate polishing on its way out through the faucet. The water delivered is of excellent quality and taste.

One thing to note though: While RO technology is known to make the best under sink water filters for the home, this particular produce filtered water to wastewater in the ratio of 1:3.


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7. Culligan US-EZ-Change Under Sink Filtration System

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This unit packs a filter head with built-in bracket, US-EZ-1 filter cartridge, chrome, lead-free dedicated faucet and fittings, mounting screws, water supply adapter and ¼” plastic tubing for your entire DIY project. The installation is easy and filter change made even easier; just twist off then twist on and it`s done.

The EZ-change system delivers clean drinking water, clear of all contaminants such as chlorine, lead, and bad taste/odor that are present in tap water offering you better-tasting water.

With a 0.5 micron rating, 0.5 GPM flow rate and 12 months or 3,000 gallons of clean water, you can say goodbye to unhealthy unfiltered water.

The unit is tested and certified by NSF against ANSI standard 42 for nominal particulate class iii and aesthetic reduction of chlorine taste/odor in drinking water. It comes with a 2-year limited warranty.


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Comparison Chart

ModelBrandOur RatingPricePro FeatureWeightDimensions
iSpring RCC7AK 6-Stage Under Sink Reverse OsmosisiSpring9.2$$$6-stage filtration system on (RO)20 pounds14.5 x 5.2 x 18.5 inches
CuZn UC-200 Under Counter Water Filter CuZn9.8$$50000 gallons capacity8 pounds4.5 x 4.5 x 15 inches
APEC WFS-1000 3 Stage Under Sink Water Filter SystemAPEC Water Systems8.8$$Super capacity filter made in US14 pounds18 x 12 x 10 inches
Aquasana AQ-5300 Under Sink Water FilterAquasana7.4$$Alerts you when it's time to change your filters6 pounds12 x 4.2 x 9 inches
Filtrete Advanced Under Sink Water Filtration SystemFiltrete
8.6$6 months or 2,000 gallons filter life2.8 pounds4 x 6.8 x 14 inches
iSpring RCC7 5-Stage Prestige Under Sink Reverse OsmosisiSpring9.0$$$Premium RO membrane34 pounds14.5 x 5.2 x 19 inches
Culligan US-EZ-Change Under Sink Filtration SystemCulligan8.2$Very easy installation2.6 pounds13 x 9 x 4 inches

Buying Guide

Hard water can be made soft by simply connecting an under-sink filter system to your tap. These under sink water filters are a safer and cheaper method of getting clean, filtered water to drink and cook with compared to installing a whole-house water filtration system or buying bottled water to drink.

Under sink filters do not only remove calcium and magnesium (the main minerals that make water hard), but also other contaminants that make water unsafe to drink. Water can be made unpleasant to drink if it has acquired a bad taste and/or smell from chlorine, chloramines or hydrogen sulfide.

Why You Should Buy An Under-Sink Water Filter

What To Consider Before Choosing The Best Under Sink Water Filter

There are considerations that must be made before selecting a water filter system to take home. Different models come in different shapes and capacities. Here is a list of particulars to look out for:

a) Certification

It is important to buy your products from renowned manufactures whose credibility is intact. The essence here is to avoid being conned into buying low quality and unsubstantial products, especially from online dealers.

Ensure that the product has been tested and certified by an independent body such as the NSF. Also, read what other people who have used the product say about its performance before making the final decision.

b) Installation And Maintenance

The good news is most of these filters are easy to install. In many cases, installation is a DIY process because all you need to do is make at least two connections and the whole installation process is done in a matter of minutes.

However, you should get a unit that has affordable and easily available replacement cartridges. Consider ease of changing filter cartridges and their lifespan. Check all this out before making a purchase.

c) Design

Check if the unit you pick can fit with your already existing tap, whether you need to purchase one, or if it comes with one packed.

See whether it demands a hole to be drilled for installation and finally consider getting something that pleases your eyes. Although they are not designed to be attractive gadgets, it does not hurt to get something that has an artistic appeal.

d) Flow Rate And Capacity

Before purchasing your filter of choice, take a look at how much water will be delivered per minute. Some filters have a very low flow rate that it becomes a bother rather than a blessing to install them. A good under sink filter should be capable of delivering at least 5 liters (possibly much more) of water per minute.

e) Filtration Ability

The main purpose of getting a filter is to eliminate contaminants that render water unsafe to drink. It helps a great deal if you know what contaminants you have so as to know what specifically needs to be filtered out of your drinking water.

You can easily find out by use of a water test kit. In the meantime, go for a unit that eliminates the most common contaminants such as chlorine, harmful chemicals, heavy metals, fluoride, lead, and sediments together with bacteria, organic and inorganic compounds.

A multi-stage filter will eliminate most of these contaminants and especially if it has a carbon filter, it will eradicate the bad smell caused by hydrogen sulfide. However, those with carbon filters are often more expensive.

How Do Under Sink Water Filters Work?

There are two main types of under sink water filters; simple under sink filters and conventional under sink filters. This is how they work:

Simple Under Sink Water Filters

The word “simple” here is basically for how easy they are to install rather than how they work. To install a simple under sink filter, all you have to do is connect the cold water line to the filter using the existing faucet.

You will not need to modify the sink or the countertop in any way or install an additional tap. Just continue using the cold water tap for filtered water and the hot water tap for unfiltered.

The only disadvantage of using simple under sink water filters is that since all the water coming through the cold water line is filtered, the lifespan of the filter cartridges is shortened significantly.

Conventional Under Sink Water Filters

Initially, only these types of under sink filters were made, hence the name. Their installation is a bit different from the simple filters because water has to be diverted from the cold water line to the filter using a short plastic tube.

Once this is done, a separate faucet has to be mounted on the sink to deliver the filtered water. The regular cold and hot water taps will keep supplying unfiltered water.

Since only the diverted water is filtered, the filter can last much longer. However, the water pressure might be affected due to the diversion and you must drill a hole on your sink to install the new faucet to deliver filtered water.

Final Words

Before going to the store or browsing through the internet for the best under sink water filter, set up a budget of the amount of money you are willing to spend. Remember that, just because it is expensive does not always mean it is the best.

Read through other users’ reviews on the item of your choice and consider looking at other options as well, so that you can make an informed decision in the end.

Consider the space available under your sink so as not to buy something that cannot fit. And finally and most important, test your water or go for a unit that has an overall filtering capacity for contaminants that pollute city or well water.

Curtis is the founder and owner of He is the lead guy concerning all the water-softening accessories in this site's guides and reviews. If he is not writing a reviews, guides or any other useful tips, you will find him testing them to find out their suitability. He is passionate about softening water. You will find him extremely helpful and always willing to educate the general populace all there is concerning water and its effects on their health and appliances.