Under-sink water filters are installed out of sight but provide advanced water filtration that improves the taste and quality of your water supply. A more eco-friendly option to bottled drinking water, these types of kitchen water filters can easily replace thousands of disposable plastic water bottles in the life span of a single filter cartridge.
Water quality is an important concern for homeowners, including those on municipal water sources or private wells. Rick Andrew, director of the National Sanitation Foundation’s Global Water Program, says: “Consumers on a public water supply should check their local water report that comes out annually to identify contaminants in their water that they may want to filter out of their tap.” Doing so will help you choose a filter that removes the contaminants present in your water supply specifically. He also suggests that homeowners who rely on a private well have their water tested annually by an accredited laboratory.
We researched the best under-sink water purifiers from the top brands, comparing options based on the type and number of filters included, the flow rate of the system, and ease of installation. We also looked for systems that have been independently tested to meet standards for water filtration systems established by the National Sanitation Foundation (NSF).
Kraus Purita 2-Stage Under Sink Water Filtration System with Digital Display Monitor
Digital display for filter life and water quality
Meets NSF Standards 53, 401, 42, and 372
Two-stage filtration system
Six-month or 700-gallon filtration capacity
Too large for some small cabinets
When choosing an under-sink water filter, you want an option that is easy to install and performs well. The Kraus Purita 2-Stage Under Sink Water Filtration System checks both boxes. It also has a digital display to provide you with useful information, including readings on water quality, battery life, and filter status. Aside from being user-friendly, independent certification assures you that it’s an effective choice, too—making it our top recommendation for an under-sink water filter in most home kitchens.
The Kraus Purita is a two-stage water filtration system with a polypropylene filter and carbon block filter, so it’s designed to remove more contaminants than single-stage water filters. Specifically, it meets the following NSF standards: 53, 401, 42, and 372. Translating those standards into practical terms, this means that it filters out particles as small as 0.5 microns and reduces up to 98 percent of lead, while also filtering out volatile organic compounds (VOCs), chlorine odor, and some trace pharmaceuticals.
Everything needed to install this under-sink water filtration system is included. This system efficiently filters water for up to six months (or about 700 gallons of water) before it’s time to change the water filter. That equates to more than 5,000 individual 16.9-ounce water bottles, making the Kraus Purita both economical and eco-friendly. While the size of the filter cartridges isn’t beyond the norm, the cartridges are larger than what may fit in a very crowded or small sink cabinet. The whole setup is 9.5 inches wide and 15.5 inches tall.
The digital display monitor is a unique feature not found on all under-sink water filters. Aside from giving you at-a-glance information about water quality, the display emits an occasional beep to alert you to low (10 percent) remaining filter life. Instead of needing to play guess-and-check regarding filter replacement, this system lets you know when it’s time for a new filter to keep your water supply filtered and fresh.
Price at time of publish: $200
Dimensions: 15.5 x 9.5 x 4.875 | Filter Type: Polypropylene, carbon block | Flow Rate: 0.75 GPM
Waterdrop 15UA Under Sink Water Filter System
Long filter life
Affordable replacement filter cartridges
Not suitable for filtering well water
A single-stage under-sink water filter system is an affordable way to improve water quality. For a budget choice, we recommend the Waterdrop 15UA Under-Sink Water Filter System. It has a twist-in cartridge with an impressively long filter life (up to 16,000 gallons), which stretches your cash because you won’t need to purchase replacement filters as often as filters with a more limited capacity.
It’s certified to meet NSF Standard 42, which addresses aesthetic water quality issues—like taste and odor from chlorine, as an example. It’s also been certified to meet or exceed NSF Standard 352, which assures you that the materials of the filter system don’t contain levels of lead deemed harmful for plumbing fixtures. And while the manufacturer claims that the system has also been independently tested to meet NSF Standard 53—which relates to the ability of the filter to remove more than 50 contaminants—it hasn’t been certified for this specific standard.
At less than $100, this option is about half the cost of more robust under-sink water filter systems. It doesn’t address as many water quality concerns as two-stage under-sink water filters, but you won’t drain your wallet to purchase this option or its filter cartridges, which only cost about $30.
Price at time of publish: $93
Dimensions: 3.6 x 3.6 x 16.7 inches | Filter Type: Polyester, activated carbon block, kinetic degradation fluxion (KDF) | Flow Rate: 0.75 GPM
Brondell RC100 H2O+ Circle Reverse Osmosis Water Filtration System
Certified to meet NSF Standards 42, 53, 58, and 372
All-in-one unit with 6-liter storage tank
Countertop dispenser with LED indicator for filter life
May not fit in crowded under-sink cabinets
Expensive filter replacement
We recommend the Brondell H20+ Circle Reverse Osmosis Water Filtration System if you want a highly efficient under-sink system with advanced filtration capabilities. You’ll spend significantly more for this model than many other options, but it has four stages of filtration, a 6-liter storage tank, and includes a countertop faucet dispenser with an LED indicator light for filter life. As you’d expect of a high-end under-sink water filter, it is gold-seal certified by the Water Quality Association (WQA) to meet NSF standards 42, 53, 58, and 372.
The four stages of filtration include a sediment filter, pre-carbon filter, carbon block, and reverse osmosis membrane. The filters require replacement about every six months, with the exception of the reverse osmosis membrane filter, which lasts about two years. The filters are somewhat expensive to replace compared to the most affordable under-sink water filters; you can expect to spend about $80 every six months and about $90 for the reverse osmosis membrane when it’s due for a replacement. However, the filters offer excellent performance. They reduce many contaminants, but they especially stand out for reducing up to 98 percent of lead and chlorine, plus 84 percent of fluoride. The 6-liter tank within this reverse osmosis system refills in less than an hour, so you’ll have a steady supply of filtered water.
The entire setup is contained in a single unit that gives this under-sink water filter a modern, finished feel worth the price tag. While the all-in-one design of this filter system is relatively compact, you should measure your space under your sink to make sure it has enough clearance around drain pipes or a garbage disposal. The list price for this one is upward of $740—but it’s frequently available at a steep discount, so if you’re not in a rush, it might be worth keeping an eye out for a sale.
Price at time of publish: $740
Dimensions: 16.5 x 9.25 x 13.8 inches | Filter Type: Carbon block, reverse osmosis membrane, sediment | Flow Rate: 0.4 GPM
Best Reverse Osmosis
APEC Water Systems ROES-50 Essence Premium Quality 5-Stage Under-Sink Reverse Osmosis Drinking Water Filter System
Gold certification from WQA
Simple to install
Removes fluoride and TDS
Subpar waste water ratio of 3:1
One type of under-sink water filter that offers advanced filtration is a reverse osmosis system. According to Rick Andrew, these types of water filtration systems filter out dissolved ions and suspended particles in the water. The APEC Essence 5-Stage Reverse Osmosis system is a popular choice for households with more advanced water filtration needs. It has gold certification from the Water Quality Association, indicating that it meets NSF standards for drinking water treatment units.
The five stages of this reverse under-sink water filter are made up of a sediment filter, coconut shell carbon, and carbon block filter, along with a reverse osmosis membrane. Together, these filter stages capture contaminants that impact taste and health, like chlorine, VOCs, heavy metals, and nitrates. The system also reduces total dissolved solids (TDS) by up to 95 percent and fluoride by 93 percent, which is not a claim that can be made by most water filter systems without a reverse osmosis membrane.
While the APEC Essence 5-Stage Reverse Osmosis Under-Sink Water Filter is one of the best options because it’s easy to install and performs well, its shortcoming is a 3:1 waste water to clean water ratio. Other reverse osmosis systems have a 2:1 or 1:1 ratio that offers better efficiency and water conservation.
Price at time of publish: $199
Dimensions: 17.5 x 16 x 5.25 inches | Filter Type: Carbon block, coconut shell carbon, sediment | Flow Rate: 0.035 GPM
Best for Well Water
Brondell UC-300 Coral 3-Stage Under Counter Water Filtration System
Three-stage filtration removes up to 99 percent of lead
Includes countertop dispenser
Gold seal certified by WQA
Certified to meet NSF Standards 42, 53, and 372
Flow rate is lower than other models
Slightly lower filter capacity
The Brondell Coral is a three-stage water filter that is ideal for well water or for anyone who prefers more advanced filtration compared to single-stage systems. This under-sink option includes a sediment filter to capture particles like dirt, sand, silt, or clay that may be present in well water sources. A pre-carbon filter and carbon block filter finish the filtration process, removing up to 99 percent of lead, along with dozens of other contaminants like asbestos, VOCs, and chloramines.
You don’t have to take Brondell’s claims at face value—the system has been certified to meet NSF Standards 42, 53, and 372. It also carries a gold seal from the Water Quality Association (WQA). You can expect to change the filters about every 12 months or once the system has filtered 600 gallons, which is slightly less capacity than the filter life of some other models. While it’s housed under the sink, the system includes a chrome faucet dispenser for countertop installation. The flow rate is 0.5 GP, which is lower than the 0.75 GPM flow rate offered by some other systems, but not low enough to be considered a serious flaw. Overall, this system gets plenty of positive praise for being easy to install and for improving the taste and quality of well water and municipal water.
Price at time of publish: $159
Dimensions: 9 x 13.5 x 3.25 inches | Filter Type: Sediment, pre-carbon, carbon block | Flow Rate: 0.5 GPM
Waterdrop Reverse Osmosis Drinking Water Filtration System
Low wastewater production (1:1 ratio)
Removes up to 94 percent of TDS
Saves space by eliminating water storage tank
More expensive than other options
Single faucet finish available
For an under-sink water filtration system that is compact yet highly effective, consider a tankless reverse osmosis system. We recommend the Waterdrop G3 Tankless 8-Stage Under-Sink Reverse Osmosis option. Rather than using a water tank, it treats water on demand using three filters to provide eight layers of purification for removing common contaminants, including chlorine and heavy metals. (Each filter offers multiple layers of filtration.)
The reverse osmosis membrane lowers the amount of TDS in your water for drinking or cooking. Under-sink water filters that aren’t reverse osmosis systems won’t lower the level of TDS in your water, but this system is certified to remove up to 94 percent of TDS. Its claims are backed by independent testing that confirms it meets NSF standard 58 for reverse osmosis water filtration systems. If you want to know real-time TDS levels, the digital display on the included countertop faucet provides this information at glance, along with a visual indicator of the remaining filter life. Take note that the dispenser faucet is only available in nickel-plated chrome.
You won’t be left waiting at the tap for a glass of filtered water; the internal pump of this tankless model fills a glass in about 12 seconds. It can filter up to 400 gallons per day, and the composite filters last six to 12 months before needing replacement, a process made easier by the single-turn cartridges that require no tools or plumbing know-how. Water waste is a big concern with reverse osmosis under-sink water filtration systems, but this option offers a low 1:1 ratio of purified water to wastewater.
Price at time of publish: $646
Dimensions: 17.72 x 5.67 x 18.11 inches | Filter Type: Carbon block, polypropylene | Flow Rate: 0.28 GPM
Best for Alkaline Water
iSpring RCC7AK 6-Stage Under Sink Reverse Osmosis Water Filter System
Alkalinity filter to restore natural minerals
Pressurized storage tank holds purified water
Certified to meet NSF 58 standard
1:3 waste water ratio
Holding tank requires more under-sink storage space
While reverse osmosis is a common choice for an under-sink water filter, the filtration process removes beneficial minerals along with contaminants, producing water that is sometimes described as flat-tasting. Whether it’s for taste or health preferences, you can opt for a reverse osmosis system with an alkaline filter to add back in minerals naturally found in drinking water. If that’s what you’re after, we recommend the iSpring RCC7AK 6-Stage Reverse Osmosis System. It’s certified to meet NSF 58 standards and removes up to 98 percent of lead, along with fluoride, arsenic, asbestos, and chlorine.
This under-sink water filter sends water from your supply line through a series of pre-filters, a reverse osmosis membrane, and two final filter stages—including an alkaline filter that restores minerals like calcium, magnesium, sodium, and potassium ions. The result is purified water with an alkaline pH level of 7.5 or more, while standard reverse osmosis systems produce slightly acidic water with a pH of 7 or less. Water is held in a pressurized 2.5-gallon storage tank until you turn on the faucet. This means you may need to rethink your under-sink storage to make space for this larger water filtration setup.
While this system gets plenty of positive praise for the taste of water and the ease of use, it does have an unimpressive 1:3 clean water to wastewater ratio. Even still, it filters up to 75 gallons per day and makes a solid pick for an under-sink water filter that produces crisp, filtered water with demineralization.
Price at time of publish: $279
Dimensions: 14.5 x 5.25 x 18.5 inches | Filter Type: Carbon block, polypropylene | Flow Rate: Not listed
Hydroviv Under Sink Water Filter
Filters are customized for your water supply
Certified to meet NSF Standards 42 and 53
Pricey replacement filters
Water quality can vary from one place to another, which is why it’s important to identify what contaminants you might need to remove from your water supply. Hydroviv doesn’t believe in a one-size-fits-all approach to water filtration and instead offers customizable water filtration filters.
Input your address and the team at Hydroviv uses publicly available water quality measurements along with the company’s own test databases to develop a custom water filtration system for your home that targets contaminants specific to your water supply. But rest assured that all Hydroviv filters meet or exceed NSF Standard 53 for lead removal.
The customizable under-sink water filter from Hydroviv is tailored to your home’s water filtration needs, but installs like most other options. It requires only simple screw-on connections to your water supply and setup can be completed in about 15 minutes. You can opt-in for auto-shipments of replacement filters at six-month intervals, which saves you 25 percent on the retail cost of a replacement filter. The filters are on the expensive side ($115 without the subscribe-and-save discount), so you may want to consider the savings you’ll get from subscribing to a filter replacement schedule, along with the assurance that your customizable water filter will remain functional and effective year-round.
Price at time of publish: $400
Dimensions: 14 x 6 x 6 inches | Filter Type: Varies | Flow Rate: Not listed
Aquasana 2-Stage Water Filtration System with Brushed Nickel Finish Faucet
Certified to meet NSF Standards 42, 53, and 401
Can fit in small spaces
Captures 61 different contaminants
Reduced filter capacity (500 gallons) compared to other models
Some leaking reported if connections aren’t tightened properly
Two-stage under-sink water filters offer additional reduction of particles and contaminants and address a wider range of water quality concerns than single-stage options. This option from Aquasana reduces 61 different contaminants, including chlorine (which affects taste), lead, and other heavy metals, plus PFOs and PFOAs. These claims are backed by independent testing to certify that the system meets NSF Standards 42, 53, and 401.
The entire system measures 9 x 8.25 x 4.25 inches, which means it can even fit in crowded cabinets. The filter housing easily twists apart so you can replace filter cartridges as needed, with no tools. You can expect the filters to treat about 500 gallons of water before needing replacement, which is short of the 600 to 700 gallons of filtration capacity that other under-sink water filters offer. Replacement cartridges run about $60 (for the set). Still, the system is efficient, effective, and easy to install. Pay close attention to the installation instructions and make sure the connections seal tightly; some leaking has been reported with this under-sink water filter system.
Price at time of publish: $116
Dimensions: 9 x 8.25 x 4.25 inches | Filter Type: Carbon block | Flow Rate: 0.5 GPM
Our top recommendation is the Kraus Purita 2-Stage Under Sink Water Filtration System because it meets several NSF standards and treats water using a polypropylene filter and carbon block filter. In addition, it has a digital display monitor to show you current information about water quality, filter status, and battery life. If you’re looking for more basic filtration and don’t need a digital display, consider installing the Waterdrop 15UA Under Sink Water Filter System. This single-stage water filter improves the odor and taste of municipal water and is certified to meet NSF Standard 42. As a budget pick, it’s worth noting that it also has long-lasting and inexpensive replacement cartridges.
What to Look for in Under-Sink Water Filters
When choosing the best under-sink water filter, you can’t ignore size and space limitations. The room available underneath your sink may determine how large of a system you can install. Single-stage or two-stage under-sink water purifiers are usually the most compact options, since they only have one to two filter cartridges. More stages of filtration usually add to the dimensions and weight of the system. As an example, the Aquasana 2-Stage Water Filtration System is only 9 inches high and 8.25 inches wide, but the iSpring RCC7AK 6-Stage Reverse Osmosis System requires much more space, as it measures 14.5 inches tall and 18.5 inches wide.
There are a variety of filter types used in under-sink water filter systems, depending on the contaminants that are being targeted by the system. Some of the most common are carbon block, granulated activated carbon (GAC), polypropylene, and reverse osmosis membranes. Note that charcoal water filters have largely been replaced by carbon block or GAC filters, which are considered to offer better filtration capability. The best at-home water testing kits can offer some general insights into the quality of your water supply, but a professional lab will be able to give you a clear breakdown of the quanitity of contaminants in your water.
In addition to the type of filter, the number of filters can affect the quality of the sink filter. Single-stage systems will reduce fewer contaminants than multi-stage under-sink water purifiers. Options that include a reverse osmosis (RO) membrane usually remove a broader set of contaminants, including fluoride and TDS, which aren’t removed by non-RO under-sink water filters.
Pay attention to filter capacity, since it indicates how often you can expect to replace the filter cartridge of your under-sink water filter. Filter life is usually estimated in months, gallons, or both. Most filters have a life expectancy of six months or 500 to 700 gallons. Once the filter reaches capacity, its performance declines significantly. You’ll need to replace the filters to ensure your water supply meets your quality expectations. Fortunately, most under-sink water filter systems have cartridges that twist off without the need for tools or excessive force, making this maintenance task fast and simple.
To ensure that your filtered water is delivered quickly to your glass, check the flow rate for an under-sink water filter system. A typical flow rate is either 0.5 GPM or 0.75 GPM. Either one will fill a standard glass in just a handful of seconds, but if you frequently fill large water bottles or cooking pots, you may want to prioritize a higher flow rate for faster fill rates. An efficient flow rate of 0.75 GPM is one reason why we recommend the Kraus Purita as the best overall water filter for kitchen sinks.
Are under-sink water filters worth it?
The advantage of an under-sink water filter is the fact that it treats water flowing from your kitchen sink, giving you filtered water for drinking, cooking, cleaning, watering plants, or any other purpose. Other types of kitchen water filters, like pitchers or countertop filtration systems, require refilling to maintain a supply of filtered water.
Installation requirements are usually minimal for under-sink water filters and the filter life is typically between six months and a year. This makes them worth it to customers seeking a water filtration system that doesn’t need to be refilled frequently or one that requires frequent filter replacements.
What water filter can remove the most contaminants?
How many contaminants a water filter can remove depends on its filter type. The highest-performing under-sink water filters typically use a combination of filters to target a wide spectrum of contaminants. As a rule of thumb, single-stage under-sink water filters that only meet NSF Standard 42 remove far fewer contaminants than systems that meet NSF Standard 53, which addresses 50 contaminants.
“Ultimately, checking the certification to confirm that a filter system is certified to filter the contaminants of concern, regardless of technology used, is the best way to assure that a filter system will meet a consumer’s specific needs,” Andrew says. So look for a filter that has third-party certification to back up its claims. In addition, you can check the NSF Product Listing Page to find certified under-sink water filter systems.
How long do water filters last?
The filter cartridges of an under-sink water purifier will eventually lose effectiveness due to accumulation of particles. How quickly this happens depends on the quality of incoming water, but most filters have a stated lifespan of about six months or 500 to 700 gallons of water treatment. The type of filter will also determine how long it lasts. A reverse osmosis membrane only requires replacement about every two years, but a carbon block filter typically needs to be replaced after about six months in most cases.
Why Trust The Spruce?
This article was written by Erica Puisis, a freelance home writer who has been contributing to The Spruce since 2017. Puisis has expertise in large and small appliances and has extensively researched water quality systems, including the best water softeners and best reverse osmosis systems. When researching the best under-sink water filters, she compared various types of filter systems. She evaluated the most popular models based on how many stages of filtration they offer, the flow rate of each system, filter maintenance, and storage tank considerations. All of our recommendations have been certified to meet at least one NSF standard pertaining to water filtration systems.
As part of the research process, Erica also interviewed Rick Andrew, director of the NSF Global Water Program. Rick spoke about the various types of water filters on the market and elaborated on the importance of choosing certified systems.