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The Best Under Sink Water Filters of 2023 Buyer’s Guide & Reviews

The best under sink water filters with activated carbon and reverse osmosis membrane to remove chlorine, lead, fluoride, and heavy metals.

Best Under Sink Water Filters 2023

Until 3 or 4 years ago, the under sink water filter, or actually any type of residential filters for that matter, is not usually considered a must-have in the US households, especially among those who use communal water.

After all, if you live in a city in the US, your drinking water has to be treated extremely vigorously before it travels to your home.

The city’s water treatment plant has to be effective, does it not? And with all the annual testing, your drinking water’s supposed to be safe.

Unfortunately, the countless water safety scandals in the recent years have suggested otherwise.

In a recent incident, drinking water in Flint, Michigan was found to contain an amount of lead large enough to cause poisoning in small children.

It turned out that while the water may be safe out of the factory, it can pick up contaminants along the way. In this case, it carried lead - the neurotoxin from the old pipes to the homes of the city’s 100,000 residents.

So, the bad news is, when the water comes out from the tap, there’s a real chance it comes with lead, arsenic, hormones, and a bunch of other contaminants that can cause health problems in the short and, more often, in the long term.

The good news is residential filtration technology has developed to the point it allows you take control and minimize, if not eliminate, the risks.

For drinking water alone, a few filter options are available. You can check out my article best home water filtration system to find the exact filter based on your needs. But generally, for a couple of gallons of pure, safe water a day for drinking and cooking, countertop and under-sink filters are your best bet. (Check the differences at the end of the article).

In the scope of this article, we will offer a detailed guide on the best under sink water filters for your home, and give a review on the ones that fit with our expectations.

Buying Guide: How To Buy An Under Sink Water Filter

Matters to keep in mind when looking for an undersink filter.

Contaminants Removed

Some, especially RO filters, can be extremely effective at removing a wide range of different heavy metals and chemicals. More simple filters, meanwhile, may be designed to only remove chlorine or chloramine.

Keep in mind what you want cleared out of your water, and check carefully if the filter you’re looking at is made to remove those contaminants before you get one. Make sure it’s NSF certified/listed for that, even if that means you’ll have to pay a little more for them.

Waste vs. Pure Water Ratio

If it’s a reverse osmosis filter you’re looking for, aim for a low waste vs pure water ratio.

Traditional RO systems typically waste a large amount of water for every gallon purified. The waste:purified water ratio can sometimes be as high as 5:1, leading to a skyrocketing water bill.

Modern RO systems have the problem sorted out. The ratio is oftentimes 3:1 and may get as low as 1:1, thanks to new technologies and sometimes special pumps to increase feed water pressure.

Filter Life

Installation and replacement of an under-sink filter can be easy or a bit time-consuming, depending on the type of filters you’re having. One thing is for sure, though: it’s no fun spending time in a narrow cabinet under the sink to change your filter cartridge.

To minimize the nuisance, look for filters that need replacing no more often than twice a year. Most modern sediment and carbon filters can actually promise that, especially if it’s tap water you’re dealing with. Well water may require more frequent filter replacement.

If you’re going for an RO filter, make sure the membrane is accompanied by several stages of pre-filters. With that, you’ll still have to change the pre-filters after every few months, but the RO membrane will stay effective for years (2 - 5 years).

Operating Water Pressure

Most water filters require stable feed water pressure in order to work properly. A filter’s operating water pressure is usually written on the product description, or on its label.

It is important to know your home water pressure condition before getting a filter. (How to measure it). If it is borderline low (close to the bottom limit of the filter’s operating pressure), consider getting a pump to speed it up.

Healthy Minerals Added

Not a must, but it’s always nicer to drink alkaline water compared to acidic water. While the health benefits are still a matter of dispute, the “sweet” taste of mineral water is remarkably more pleasant to most people.

In reverse osmosis, aka RO systems, remineralization of the water before it travels to the tank also means reduced acidity levels, which minimizes degradation of the tank. This feature is available on the Home Master Artesian and HydroPerfection, which are among the list of filters we’ll be introducing in this article.


Nothing good is cheap, and the same applies to under sink water filters. A strong filter system typically costs more than 200 dollars. Some can be worth more than half a grand.

That said, the most expensive systems are not necessarily the best ones for you. Sometimes they include features you don’t particularly need (designed to remove 99% nickel, and there’s a very safe amount of nickel in your water, for example). Not that it can hurt to have those features, it’s just unnecessary, especially if you’re on a budget.

Review of The Best Under Sink Water Filters 2023

Out of more than 10 brands of undersink water filters we found on the market, we picked out the best four reverse osmosis filters and one simple filter following the criteria of filter quality and lifespan, water efficiency, and price.

Here’s our picks for the Best Under Sink Water Filters.


Home Master Artesian

iSpring RCC7AK

APEC Top Tier Alkaline

Home Master TMHP

CuZn UC-200

Removes >98% chlorine






Removes >94% fluoride






Removes >98% lead, mercury, arsenic

Yes, except arsenic III

Yes, except arsenic III

Yes, except arsenic III

Yes, except arsenic III

Yes, except arsenic III

UV light






Fast flow pump






Full Contact Technology






Alkaline water






Water waste: Pure water ratio*






Minimum water pressure

40 psi

45 - 70 psi

40 psi

40 psi

No specific requirements


NSF listed companyNSF certified components

NSF certified

NSF certified components


NSF certified media

1. Best Overall: Home Master TMAFC-ERP Under Sink Water Filter

The Home Master TMAFC-ERP Artesian is an under-sink water filter that sets the standards for others in the industry with its efficient and long-lasting filters, and a pure water:waste water ratio of 1:1.

  • Effective in removing contaminants
  • Low waste water ratio
  • Fast flow with pump
  • Alkaline water
  • NSF listed
  • Faucet included
  • The loaded package is a bit pricey to most people (but it’s worth every penny!)

A Complete, Well-rounded System

The TMAFC-ERP Artesian is made in the US with NSF certified components by Perfect Water Technologies, Inc., an NSF listed manufacturer.

This package of under-sink water filter comes with an RO membrane, pre-filters to protect said membrane, a post-filter and remineralizer for alkalinization of the water after filtration, a tank for pure water storage. Also in the package are a drain saddle, fittings, tubing, and an adapter. It also includes a faucet so that you can have purified water from a separate tap.

That’s everything you need for pure alkaline water from your own kitchen.

Improved Flow Rate And Incredibly Low Waste

One of the biggest problems with RO water filters is that they tend to produce lots of wastage before they can offer a gallon of clean water. The waste:purified water ratio can sometimes get as high as 5:1.

The Home Master TMAFC-ERP comes with a permeate pump that works to improve the system efficiency. It reduces up to 80% of wastewater. As a result, the waste:purified water ratio is probably the lowest among reverse osmosis systems: 1:1.

The good thing is, this pump uses energy from the reject water, and thus doesn’t even require electricity to work!

Super Effective Water Filtration

The system includes a set of 3 filters: a spun poly sediment filter, a catalytic carbon filter, a coconut shell granular activated carbon water filter, and the RO membrane. When water comes out of your faucet, up to 99% of dissolved solids, chemicals & metals are already removed.

The catalytic carbon filtration media in the pre-filter is a special feature in this system. This material is one of the few that are highly effective in removing chloramine, a chemical disinfectant used widely in the US to replace chlorine.

Not only that, but the Artesian remineralization also allows healthy minerals, calcium and magnesium in particular, back into the water, making it slightly more alkaline. This will show in your water TDS reading, so don’t be surprised if the number’s above zero!

Innovative Filter Design

In traditional RO systems, the filter housing is kept for re-usage every time a filter is changed, posing risks of re-contamination. The Home Master TMAFC-ERP, meanwhile, has a modular filter design, where the filter and its housing are incorporated into one single unit and are disposable together. This makes it slightly more expensive, but is better hygienically.

These filters can last about 2000 gallons, and it is recommended by the manufacturer to change it once every year. (Replacement filter)


This is probably the easiest RO system to install on the market. The membrane and filters come readily assembled, so you don’t have to worry about it.

Installation typically takes about 50 minutes.

The process may involve some drilling and screwing, however, for the filtered water dispenser. Therefore, if you’re not exactly a handyman or handywoman, it’s best to ask for the help of a plumber.

Price at time of publish: $351.96

Key specs:

  • Filtration method: Reverse osmosis, sediment filter, artisan filter, carbon (in modular)
  • Pure to drain ratio: 1:1
  • Remineralization: Yes
  • Dimensions: 20L x 16W x 12H inches
  • Certifications: NSF certified components, NSF certified manufacturer
  • Warranty: 5 years limited warranty

2. Best Value: iSpring RCC7AK 6-Stage Drinking Water Filter System

Coming with a reputable multiple-stage filtration and remineralization system that passed all the vigorous testing requirements to win a WQA Gold Seal, the iSpring RCC7AK is another under sink filter that we highly recommend.

  • Affordable
  • Removes 98% of lead, chlorine, other contaminants
  • WQA certified
  • Good customer service
  • Lead-free brass faucet included
  • High wastewater:pure water ratio (3:1)

You simply can’t beat that price for the excellent quality of water it offers.

Purified Water With 5-Stage Ro Filter

The pureness of your drinking water is guaranteed with this iSpring system – it is certified against NSF/ANSI standards.

It removes up to 98% of lead, if there’s any in your water. 99% of a thousand other pollutants will also be taken care of, including chlorine, fluoride, arsenic, hormones, asbestos, bacteria, and viruses.

This is thanks to its well-known 5 stages of water purification, with 3 pre-filters including a fine sediment mesh, a granular activated carbon core, and a carbon block.

After the pre-filters, the water will pass through the RO membrane with pores as small as 0.0001 micron, and become purified.


On the RCC7 5-stage system, after the RO membrane, the water is polished with only a post carbon filter before travelling to your faucet. The problem with this system is that it filters out not only toxic heavy metals, but also minerals that are important to your body, and makes the taste slightly acidic.

On the RCC7AK 6-stage system, Ca+ and Mg+ are reintroduced via an extra remineralization process. While this won’t create a significant change on your mineral intake, it alkalizes the water and brings a “sweeter”, more natural taste to it.

The Filter

With 3 stages of pre-filtration, the water has become very clean before it even gets to the RO membrane. That is why the iSpring RO membrane can last up to 3 years.

Other parts of the filtration system can last up to one year, as do in most RO systems. You can change it a little sooner or later depending on the quality of the water in your house. The polypropylene pre-filter has a clear housing, allowing you to see the sediments removed from your water and building up. You will get an idea of when to change it.

One thing to note: the system produces wastewater at a ratio of 3:1 at its best. If feed water pressure is low in your house (lower than 50 psi), purchasing a permeate pump to speed things up and reduce wastewater may be a good idea.

Price at time of publish: $213.99

Key specs:

  • Filtration method: Reverse osmosis, activated carbon, carbon block, sediment filter
  • Pure to drain ratio: 1:3
  • Remineralization: Yes
  • Dimensions: 15.5L x 5.1W x 19.5H inches
  • Certifications: NSF 58, NSF certified manufacturer
  • Warranty: 1 year manufacturer warranty

3. Best for Alkaline Water: APEC Top Tier Alkaline Mineral pH+ 6-Stage

If you’re looking for an under-sink RO system that frees your water from toxins but keeps the beneficial minerals in it, get the APEC Top Tier Supreme Alkaline Mineral pH+.

  • Removes 99% arsenic, fluoride, lead, and other contaminants
  • Mineralization for alkaline water
  • Improves taste and odor significantly
  • Faucet included
  • Higher waste:pure water ratio (3:1)

5 stages of water purification

Like most other high quality RO systems, the APEC offers 5 stages of water purification.

The first is a rough filter made of polypropylene sediems. It removes larger particles, rust, and dust from the water, protecting the membrane life. The water then goes through 2 carbon block membranes, where 99% of chlorine, odor, and any weird tastes are taken care of.

Next, there’s a High Rejection TFC RO membrane to even further remove any contaminants in the water. This membrane gets rid of heavy metals such as arsenic, lead, chromium, radium, as well as fluoride, bacteria, and viruses.

Finally, as it leaves the storage tank, the water goes through another coconut shell activated carbon for removal of any odor it picks up during its time in the tank.

The APEC can produce 90 gallons of pure water per day - the highest output of the 4 RO systems in this list.


After the post-filter, the water has become pure and is safe to consume. For increased healthy mineral intake, however, calcium carbonate is added into the water in an alkalization stage, which also improves its taste and smell.

Note, however, that the pH level of the treated water will only increase by 1 to 2 points, which already translates to 10 - 100 times in alkalinity. If your tap or well water has a pH of 5, it will most likely increase to 6.5 maximum. Don’t expect it to come out of the filter becoming bottled sports water alkaline at 8 or 9.


Installation typically takes about 60 minutes from start to finish. Like other undersink filtration system, it takes some basic drilling/screwing work. Follow the instructions carefully and you should be good.

If you hate spending an hour or two in a cabinet under the sink, however, calling a plumber is also a good option.

Price at time of publish: $222.59

Key specs:

  • Filtration method: Reverse osmosis, activated carbon, carbon block, sediment filter
  • Pure to drain ratio: 1:3
  • Remineralization: Yes
  • Dimensions: 16L x 5.25W x 17.5H inches
  • Certifications: N/A
  • Warranty: 2 years extended manufacturer warranty

4.  Best for Well Water: Home Master TMHP Reverse Osmosis Filter System

Most RO filtration systems can work very well on tap water. Well water, however, is a different story.

  • Effective in removing iron, chlorine, lead and other heavy metals
  • UV light to destroy microorganisms
  • Water is remineralized
  • Low waste: pure water ratio (1:1)
  • Faucet included
  • High price
  • Requires electricity (for UV light)

Unlike tap water, well water is usually not treated with chlorinechloramine, or fluoride. Therefore, such chemicals are much less of a problem. Sediments such as sand, rust, and microorganisms and heavy metals, however, are very often found in well water.

In many parts of America, well water is usually specifically rich in iron. While it’s unlikely that you can get an overdose of the metal from drinking the water, iron usually comes with trace impurities and harbor bacteria which are potentially harmful. It also tend to leave rust stains on your sink and ceramic dishes.

So, if you’re using water from a private well, you want a filtration system that can take care of the iron, the microorganisms, along with other heavy metals, at the same time softening the water.

There’s one that is designed to take care of the job: the Home MasterTMHP HydroPerfection.

An Advanced Purification And Softening Process

With an RO membrane, the HydroPerfection is among the most effective under-sink water filtration systems to purify and soften well water.

To prevent iron from damaging the RO membrane, the system is also equipped with an iron pre-filter which contains advanced redox media KDF85. Together, the RO membrane and the pre-filters can clear out 99% of chemicals, heavy metals (water-soluble lead, mercury, nickel, chromium, ect), sediment, pesticides, and other contaminants. It also removes 98% of iron, eliminating the typical metallic taste from well water.

Uv Light To Get Rid Of Viruses And Bacteria

After passing through the RO membrane, the water is essentially purified. To further make sure it’s free of any disease-causing microorganisms, a UV light, one of the 4 methods approved by the FDA to purify water, is employed.

This light that produces short wavelengths is known for being effective at breaking molecular bonds within the organisms’ DNA and killing or disabling them. So, any bacteria and viruses that can pass through the RO membrane will be destroyed in this process.

But the HydroPerfection doesn’t stop there…

Alkaline Water

After purification, the water is often time slightly acidic. This is because the RO membrane is so effective it happens to also filter out essential minerals from the water.

The Home Master HydroPerfection offers remineralization at two points. It releases a small amount of minerals before the water travels into the tank (to prevent tank degradation from the acidic water) and before it gets to the faucet.

While it won’t turn a pH 4 into a pH 9, it does balance out the purified water and make your water slightly more alkaline.

The only reason why this system doesn’t become the best-buy in our list is its high price, partly due to the added UV light. This gadget is quite useful if you use well water. However, if you’re using tap water, chances are most of the microorganisms are already deactivated before they reach your home. Not that it will hurt to have the UV, it just isn’t necessary.

Price at time of publish: $439.27

Key specs:

  • Filtration method: Reverse osmosis, ultra violet, sediment filter, artisan filter, carbon (in modular)
  • Pure to drain ratio: 1:1
  • Remineralization: Yes
  • Dimensions: 15L x 5W x 16H inches
  • Certifications: N/A
  • Warranty: 5 years limited warranty

5. Best Non-ROUnder-sink Filter: CuZn UC-200 Under Counter Water Filter

Talking water filtration, you can’t ignore CuZn. It was an easy decision for us to nominate its UC-200 as the best non-RO under counter filters on the US market in 2023.

  • Reduces chlorine, sediments, lead, heavy metals.
  • Improves water taste and odor Easy installation.
  • Does not affect flow.
  • Good customer service Filter lasts 5 years.
  • Not designed to remove TDS

Fuss-free installation

Apart from praises on water quality improvement, the reason this undersink filter is so welcomed into the American homes is that it’s super easy to install. It comes compact and simple with a braided stainless steel compression hose. All you need is 5 minutes and a crescent wrench to connect it into the cold water line.

In fact, you can even connect it to the hot water line. According to the manufacturer, the durable housing would allow that and water quality will be improved, though at a slightly lesser level.

Don’t even worry if it’s non-standard plumbing you have in the house – CuZn is known to have a super responsive customer support team who will offer thorough consultation to their customers. Better yet, they also provide non-standard kits for free.

One thing to note before purchase, though: don’t let the photos fool you. The unit will most likely be larger than you expect. Dimensions are 4.5 x 4.5 x 15 inches, so make sure your cabinet can accommodate the filter when it arrives.

3 Stage Filtration Process

The CuZn filter consists of 3 different layers of filtration media.

The outermost of the filter are micro sediment membranes. This takes care of larger sediments – think sand, plastic fibers, and rust.

Inside the membranes is acid washed coconut shell activated carbon, which targets chemicals such as chlorine, chloramine, herbicides, pesticides, and reduces any weird taste or odor in the water.

Finally, there’s a layer of KDF 55, an NSF certified medium, to further control scale, bacteria and algae, and remove inorganic contaminants (water soluble heavy metals like lead and mercury).

Unlike RO filters, these media allow healthy minerals (calcium and magnesium) through. Water will taste and smell better, but there won’t be too large of a change on the number on a TDS meter, so if your goal is to reduce TDS, the APEC or the iSPRING system may be a better choice.

Long Filter Life

For municipal water in most places, CuZn can last about 50,000 gallons of water. Which means once you’ve installed the thing there, you can basically forget about it. Replacement time won’t come until 5 years later.

Mileage may sometimes vary due to water quality, however, so if there have been reconstruction activities going on around and you’re concerned about that affecting water quality, taking a visual inspection at the filter may be helpful. With a clear housing, it allows you to see through to check if the sediment filter is overloaded.

If it is, definitely call their customer service line; they may offer a solution or a replacement depending on the usage duration and other factors. One thing most customers have reported is that the support team will go out of their way to make sure you’re satisfied with the product.

Price at time of publish: $116.17

Key specs:

  • Filtration method: KDF-55, sediment filter, carbon
  • Pure to drain ratio: N/A
  • Remineralization: N/A
  • Dimensions: 16L x 4.5W x 16H inches
  • Certifications: NSF certified components
  • Warranty: 5 years prorated performance warranty

How To Install An Undersink Filter

The installation of an conventional undersink water filter typically involves the following steps:

  1. Drill a hole on your sink or countertop for the drinking water dispenser if your sink doesn’t already have one spare hole. Secure the dispenser into the hole.
  2. Turn off the cold water valve under the sink. Drain the cold line.
  3. Install the fitting to the cold water supply.
  4. Connect the tubing from the system to the fitting and the new faucet.
  5. Run the filtered water for 5 minutes before using.

For the simple filter type, no separate dispenser is needed. Simply integrate the filter directly into the cold water line and the job is done.

If it’s a RO system you’re dealing with, the installation can be a bit more complicated and time-consuming. A words-only instruction probably wouldn’t be of much help, so take a look at this detailed instruction video below. The series features the installation of a Home Master RO system from start to finish.

Why You Should Install An Under Sink Water Filter

They’re becoming very popular among households in the US. And for good reasons.

They’re Oftimes Advanced Filters

Advanced filters

Since they stay under the sink, these filters are typically large and oftentimes complicated systems. Four out of five filters reviewed in this article are Reverse Osmosis systems, which are the most powerful in removing pollutants from water. They consist of several steps of pre-filtration before the water actually travels to the RO membrane, thus maximizing the filtration efficiency.

After the RO treatment, the water becomes very safe to drink. More than 90% and up to 99% of most contaminants, from chlorine to heavy metals like lead and chromium are removed.

A few have a UV lamp to further destroy any living organisms. Some systems go further by adding back some minerals into the water, making it taste “sweeter”.

The result? High quality purified alkaline water right out of your tap.

Long Filter Life

Due to their large size and complicated system, most quality under-sink filters can last quite long.

Six to 12 months is the general consensus for a pre-filter if it’s communal water you’re using (well water that is not filtered at the point of entry may require more frequent replacement of the sediment and carbon filters). An RO membrane, meanwhile, can last up to 5 years. These are turtles compared to faucet filters or small countertop filters, which require replacement every 2 - 3 months.

They Take No Countertop Space

Under-sink Filter

Countertop filters can be effective in removing contaminants from your tap water, but let’s face reality: they’re no treats to the eyes. The best a counter-top filter can do to the aesthetics of your kitchen is only to not destroy it.

Nor are under-sink filters any eye candy. In fact, they tend to be a lot bulkier and yes, uglier.

The good thing is they are made to hide under the sink, leaving space for other kitchen items. Apart from a small extra faucet for purified water (if it’s an RO or a conventional filter), all parts of these systems - the wiring, tubing, cartridges, tanks, etc - are completely out of sight. You can technically forget about it until replacement time.

The Different Types Of Under Sink Water Filter, And How They Work

There are three main types of undersink water filter: conventional filter, simple filter, and RO filter.

1. The Conventional Under-Sink Water Filter

A conventional filter is one attached to your cold water line, allowing the filtered water to pass through and come out from a separate faucet. Unfiltered water, both hot and cold, can be used from your original faucet.

Since they require an additional faucet for filtered water and fittings to attach to the cold water line, conventional filters can be a little tricky to install. If you don’t already have an extra hole available on your sink /countertop for the faucet, some drilling will be necessary.

On the other hand, because the filtered water is separated from unfiltered water, the filter life is prolonged compared to the simple version.

2. The Simple Under-Sink Water Filter

A simple under-sink filter processes water from the whole cold water line. Water will then be dispensed through regular faucet - no additional faucet is needed.

As they filter more water, these filters typically have shorter life spans, and require changing more often than conventional filters.

On the other hand, since they only require a simple connection to the cold water line to work, these under-sink filters are the easiest and quickest to install among the three kinds of filters. Installation typically takes only minutes, and does not require a plumber. That is one of the reasons these simple filters are getting very popular, especially among families and individuals living in rent apartments and houses.

3. The Reverse Osmosis Filter

A reverse osmosis (RO) filter employs the reverse osmosis process to flush away contaminants from the water. Pure water will then be dispensed through a faucet (usually a separate one from the regular faucet), while “wastewater” - the water with all the contaminants, will be drained away or used for non-drinking purposes.

See The best reverse osmosis systems and how they work

Since the RO membrane is extremely fine, it is usually accompanied by several layers of pre-filters to make sure larger sediments and pollutants are removed from the water even before it travels to the membrane. This promotes efficiency, making RO filters so far one of the most effective non-electronic devices for purifying water.

But that comes at a price. RO filters are also some of the most difficult systems to install.

Mileage may vary, depending on the design of the system itself, the space you have under the sink, and your plumbing skill proficiency, but it usually takes somewhere between 30 minutes to 2 hours to set one RO filtration system up. If you’re unfamiliar with plumbing work, you may have to resort to calling a handyman or a professional plumber. That contributes to the higher total price of these filters compared to the conventional and the simple filters.

Under-Sink Filter Vs Countertop Filter

If you’re contemplating which one to buy, here are a couple of things to keep in mind.

The Similarities

Both under sink and countertop filters are larger filtration devices or systems (compared to, say, faucet or showerhead filters). They tend to have a big capacity, and employ advanced filtration technologies to purify water to a drinkable level.

In fact, the two filtration systems may sometimes have the same features. For example, the reverse osmosis process is oftentimes seen employed on both types of filters.

The Differences

1. Location of installation

The first and the most obvious difference between the two filtration systems is suggested right in their names: one takes up space on the countertop (or table top), while the other is hidden in a cabinet under the sink.

This means if you have a small kitchen and want to utilize your countertop space, an under sink system may be a better choice.

The location of installation actually leads to many other differences between these two kinds of filters.

2. Size and capacity

First, since under-sink systems are installed out of your sight, they are usually larger (as large as the cabinet allows) and have a stronger capacity than their countertop counterparts. They typically consist of bigger and more complex cartridges that require less frequent replacement.

Countertop filters, meanwhile, are usually made more compact to save space. This translates to smaller, less complex cartridges.

3. Method of filtration

Under-sink filtration typically takes advantage of the in-house water pressure. The process involves the water running through one or more cartridges of different materials, leaving impurities behind. In more advanced systems, RO is employed.

There are, meanwhile, more options when it comes to countertop filters. Apart from cartridge and RO filtration, gravity filtration and electrolyte filtration are also widely adopted.

4. Ease of installation

Since under-sink filters are connected to the pipeline, they tend to require some drilling, screwing, and wrenching, all of which have to be done inside a small cabinet. Most modern filters are now made extremely easy to install; nevertheless, they still require about half an hour working in the limited space under the sink, which is no picnic to anyone.

Countertop filters are oftentimes much easier to install, if that has to be done at all. A simple attachment of the filter’s connector to the faucet, and you’re good to go. Some has its own tank that requires no installation; you can routinely fill them with a pull down faucet.

Under-Sink Filter Vs Whole-House Filter

Should you install an under sink filter, a whole house filter, or both?

Before getting on to that, let's investigate the differences between the two types of filters.

1. Location of installation

An under-sink water filter is apparently installed under the sink, at the point of use. The whole-house filter, meanwhile, is placed at the point of entry, where the water first enters your house pipe system.

This means installation of the whole house filter tends to be more difficult, not only because of the bigger size alone, but also because during the process water supply to the whole house will have to be ceased.

2. Size and capacity

Designed to take care of the water in the kitchen, an undersink filter typically has a large capacity. A large and strong simple under-sink filter can last several years and filter up to 50,000 gallons of water. RO under-sink filters can process less water (1000 - 5000 gallons) in its lifespan, but with higher level of pureness.

Whole house filters have the biggest capacity of all residential water filters. Due to the fuss associated with water supply shutdown for a replacement, these filters are designed to last longer, usually more than 6 months. Some of the biggest whole house filters can last up to 10 years and process a million gallons of water.

3. Method of filtration

Used for drinking and cooking water, under-sink filters are designed to remove not only sediments but also a large amount of heavy metals and chemicals in the water.

An under-sink filter typically consist of several cartridges, or a cartridge with several layers of sediment filters and activated carbon or carbon block filters. More advanced under-sink filtration systems also employ reverse osmosis membranes to maximize water purity.

Mechanical filtration is also applied on whole-house filters, except usually at a larger scale.

Whole house filters have to process a huge amount of water for a wide variety of everyday uses, from cooking to washing, cleaning, and even watering. Therefore, strong filtration methods such as reverse osmosis are not usually employed as they’re cost-inefficient.

For high quality water for drinking and aesthetically pleasant water for other uses, the most common setting is a simple whole house water filter or a whole-house water softener with a pre-filter, plus an RO filter under the sink or on the countertop for drinking water.

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Our Expertise

Luna Regina has been researching and writing on water quality and water filtration since 2018. She has developed test methods and carried out the tests on a wide variety of water filters, including countertop filters, pitchers, shower filters, undersink, and whole-house filters and water softeners. Luna’s works have been featured on CNN, Business Insider, and Forbes. She has also gained impressive plumbing skills from her years of work with the filters.

About your guide

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Luna ReginaEditor

Luna Regina is an accomplished writer and author who dedicates her career to empowering home cooks and making cooking effortless for everyone. She is the founder of HealthyKitchen101.com and HealthyRecipes101.com, where she works with her team to develop easy, nutritious recipes and help aspiring cooks choose the right kitchen appliances.

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