Brittany Natale

Author: Medical reviewer:

April 10, 2023

Brittany Natale


By Brittany Natale


Brittany Natale has a degree in advertising and marketing communications from the Fashion Institute of Technology. Her work has appeared in SELF, Popsugar, i-D, Teen Vogue, Domino, Martha Stewart, and Eat This.

Scott Nass, M.D., MPA, FAAFP, AAHIVS

Medical review by

Scott Nass, M.D., MPA, FAAFP, AAHIVS

Board-certified Family Physician

Scott Nass, M.D., MPA, FAAFP, AAHIVS is a family physician and HIV specialist in California. He takes a holistic approach to healthcare, incorporating principles of functional medicine and using food as medicine when working with patients.

the best under sink water filters

April 10, 2023

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If you’re looking for ways to make tap water healthier, under-sink water filters can get the job done. The best under-sink water filters can be hooked right up to your plumbing to make tap water safer by filtering out contaminants and other impurities, many of which could be detrimental to your health. For instance, research from the National Cancer Institute indicates specific tap water contaminants, including nitrates, chlorine, and arsenic, may be linked to higher cancer risk. Separately, a 2021 study review found excess fluoride in drinking water may cause arthritis, osteoporosis, fatigue, and joint damage1

Navigating the world of water filters may feel overwhelming, so we did the hard part for you. Using research, expert insight, and reviews, we rounded up some of the best under-sink water filters out there right now. Plus, we’re sharing everything you need to know about the differences between under-sink water filters and the importance of deciding on one that works best for your wants and needs.

Types of under-sink water filters

Riggs Eckelberry, founder and CEO of OriginClear, a clean water innovation hub, says three types of under-sink water filter systems are commonly used. “Typically, you’ll see single-stage filtration systems, which essentially utilize one method of filtration, and multistage filtration systems, which are filters with multiple levels or types of filtration,” he explains. “There’s also reverse osmosis filtration systems, which is a specific type of physical filtration wherein even very tiny particles are physically removed.” 

Rick Andrew, senior director at NSF (National Sanitation Foundation), explains that the main difference between reverse osmosis and more traditional filtration systems is how the water is filtered. “A reverse osmosis system uses a semipermeable membrane to separate out the suspended and certain dissolved solids from the water,” Andrew says. “On the other hand, a filter works by providing a physical barrier that the contaminants can’t pass through to separate them from the water, or an active media that adsorbs or absorbs contaminants from the water.” He points out that each type addresses a specific situation, so it’s best to know what you must treat first before picking up a filter system. 

How to choose the best under-sink water filter

According to Andrew, there is a broad range of technologies, configurations, sizes, and price points for under-sink water filters. “The type of water filter someone will prefer will differ from consumer to consumer depending on what they want to filter out, how they would like the filter to be installed or used, their budget, and other factors,” he says.

As a starting point, Andrew recommends determining what’s actually in your water that you want to filter out. To do this, he suggests checking your local water quality report. This will help narrow your search to filters that can remove those specific contaminants.

If you’re not sure where to start, it turns out you can do this easily online. “I always recommend checking out the Environmental Working Group’s Tap Water Database first to see what type of contamination you’re dealing with in your ZIP code,” Eckleberry echoes. 

In addition, Andrew suggests consumers look for a water filter that’s certified by the NSF. “NSF-certified water filters are rigorously third-party tested to ensure they work according to the manufacturer’s claims and are safe to use and won’t leak,” he explains.

How we picked:

High-quality products last longer and are often safer to use. We were sure to choose systems that fit the bill. 

Although these picks are our own, we kept expert insight in mind when building our list.

Water filter systems vary significantly in price. This in mind, we include options that fit into a variety of budgets.

People’s experiences with a product may vary. We combed through hundreds of reviews to get a better sense of how people use these filters, what they like about them, and what they wish they could change. We called attention to highly rated picks that have an overwhelming number of positive reviews.

The best under-sink water filters of 2023:

Best compact: Aquasana 2-Stage Filter System AG-5200


  • Compact
  • Easy to install
  • NSF/ANSI-certified

Return policy: 90 days Aquasana, 30 days Amazon

Dimensions: 8.25” x 4.25” x 9”

Under sink water filters don’t have to be large and bulky. If you want to invest in an under sink water filtration system but are low on space, this one’s for you. This pint-sized version, which is only 9 inches high and a little over 8 inches wide, can easily be installed under your sink without taking up much room. 

Each system has an NSF/ANSI-approved Claryum dual-stage filter that removes up to 99% of contaminants found in tap water while leaving in healthy minerals like potassium and magnesium. If you want a low-maintenance system, look no further—each filter lasts about six months, on average, translating to approximately 500 gallons before it has to be replaced. Replacement can also be done in a cinch—just snap off the old filter and lock in the new one. 

One happy customer writes, “So compact and tastes so good. I had no trouble installing it myself, just had to get a drill bit for the faucet to be installed in my sink. Highly recommend.” Many people approve of this under sink water filter, but one did mention that they wish the filters lasted longer.

Best for well water: APEC 5-Stage Reverse Drinking Water System


  • Removes 99% of contaminants
  • Noise-free system
  • Comes with designer faucet


  • Special install tools may be needed

Return policy: 30 days

Dimensions: 16” x 5.25” x 17.5”

If you have well water that tastes or smells bad, consider picking up this system. Easy to install and use, this WQA-certified option does a great job of transforming unpalatable well water into a quality you actually want to use. It helps reduce 99% of contaminants (including chlorine, fluoride, and lead), improve taste and odor, and even comes with a designer faucet. 

Made by one of America’s top-rated water filter brands, this APEC system boasts high-quality leak-free connect fittings that require zero sealing (no running to the hardware store during installation) and everything you need to put it together yourself. Even better? The system is noise-free, so you don’t have to worry about loud rumbling during all hours of the day. 

With over 9,000 five-star ratings on Amazon, this popular under sink water filter is especially praised for its straightforward installation and exceptional design. “The taste of our well water was transformed after installing this,” one Amazon shopper writes. “We save hundreds of dollars a year because we no longer buy bottled water. The taste is better than any bottled water out there. I’ve had 3 people so impressed with this system that they purchased their own.” Thousands of people recommend this useful filter, but a couple do point out that, depending on your sink setup and plumbing, you may need additional tools for installation.


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Best ultrafiltration: Waterdrop Ultra-Filtration Under Sink Water System


  • Has smart indicators
  • Filters last between 6 and 24 months
  • Comes with a stainless steel faucet


  • Requires you to drill a hole in your countertop
  • Consult with doctor if allergic to coconut

Return policy: Not specified

Dimensions: 18.39” x 6.38” x 18.62”

This high-quality under-sink water filter takes water filtration to a whole new level. Water goes through not one, not two, but three layers of filtration that help reduce levels of chlorine, odor, and other contaminants. Every system comes with a stainless steel faucet, a water inlet hose and a water outlet hose—basically everything you need to put it together yourself (which reviewers say only takes a few seconds to do). 

Even better? The filters have smart indicators that alert you when any of the three filters need to be switched out. Each filter lasts between six and 24 months, and the replacement process isn’t too tricky. It’s important to note that the carbon blocks used in this device’s filters are made from natural coconut shells, which may be detrimental for those allergic to coconut. Also, installation requires you to drill a hole in your countertop, so make sure yours can withstand this step.

“I rarely write reviews but this warranted it six months later!” one elated reviewer writes. “The water tastes great and it is so easy to replace the filters. I needed a system that needed to sit at the bottom of the kitchen cabinet and it’s perfect. I couldn’t say enough about it. They make it easy to order filters, have a QR code right on the box, everything about it is user-friendly and the quality is superb.”

Best reverse osmosis: iSpring 6-Stage Reverse Osmosis System


  • Helpful customer service
  • 6-stage filtration system
  • Easy installation

Return policy: 30 days

Dimensions: 14.5” x 5.25” x 18.5”

A great choice for those who prefer a reverse osmosis under-sink filter, this NSF-certified, heavy-duty option boasts thousands of 5-star ratings and features a 6-stage alkaline remineralization layered filtration. In other words, not only does this filter remove up to 99% of contaminants (like chlorine, lead, and calcium), but it also restores water’s natural alkalinity levels and mineral content. This is what helps give its filtered water such a great taste.

Constructed to fit perfectly under kitchen sinks, this system has been specifically designed for DIY installation. Each kit comes with an instruction manual, instruction videos, and easy access to technical support. 

Shoppers love this under sink water filter for its quick and easy installation and helpful customer service that’s available if you run into any issues. A few customers mention that this model is slightly bulk and takes up considerable room. Be sure to measure the space under your sink before adding this one to your cart.


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Best budget: Waterdrop 10UB Under Sink Drinking Water Filter System


  • Fast flow rate
  • Includes stainless steel faucet
  • Made from BPA-free and lead-free materials
  • Quick installation


  • Directions not very clear

Return policy: 30 days

Dimensions: 1.54” x 1.42” x 4.84”

This wallet-friendly under sink water filter is an excellent option for those looking to upgrade their tap water for a lower investment. Each system is made from BPA- and lead-free materials that are either WQA- or NSF/ANSI-approved. It does a great job at reducing impurities, like lead, chlorine, and heavy metals, often found in tap water, and its filter has a 12-month maximum service life. This equates to approximately 8,000 gallons. 

What’s more, this particular under sink filtration system features a “push-to-connect” design. This means it can be installed in just a few minutes, which is great news if you’d like to put it together yourself. Every kit includes a design-forward stainless steel brush faucet with a fast and stable flow rate, so you won’t have to wait forever for your water to come out. 

This pick is strongly recommended by nearly 2,000 Amazon reviewers who gave this system a perfect five-star rating. One writes, “I had my handyman install it for me. It took him about a half hour. Anyway, it looks great, and the water tastes good. Also very affordable.” 

A few people do mention that they wish the directions were clearer. Others share that installation customization (such as using more washers) may be necessary in some cases.


Which water filter removes the most contaminants?

Reverse osmosis is considered one of the most comprehensive water filtration methods out there. However, this can vary depending on the product, so it’s best to thoroughly read up on each one before making a decision.

Do under-sink water filters waste water?

Eckelberry explains that this will vary from system to system and that zero-waste filtration systems are available if that’s a concern of yours.

How long do under-sink water filters last?

How long an under-sink water filter lasts depends on the filter. While some last for six months, some may last far longer.

The takeaway

The best under-sink water filters reduce impurities and contaminants commonly found in tap water, making it safer and healthier to drink water directly from your sink. If you’re interested in learning more about water filtration and all that it entails, be sure to check out our ultimate guide to water filters and reasons why you should filter your water.