If you find the water from your tap has a bad taste or an off-putting odor and you’re concerned with its quality, an under-sink water filter could be your solution. A recent study found that as many as 63 million Americans or 1 in 5 people have been exposed to potentially unsafe water multiple times in the past decade. So finding the right filter is a very important consideration for your health and safety.

Finding an affordable and effective water filtration system can be daunting — between understanding all the differences in types, models, installation, and varying filtration methods, it can be a confusing process for many consumers.

Under-sink water filters are among the most popular choices for homeowners who are looking to filter their water. Apart from being affordable and durable, under sink systems are actually fairly easy to install and require very limited maintenance.

Plus, you’ll be rewarded with an unlimited source of pure water that’ll make it tough to go back to drinking unfiltered water.

Under-sink filters are a point-of-use product (POU) which means it can be installed at the exact location you need access to cleaner water. Apart from bringing your home instantly filtered water, under-sink water filters help to alleviate the carbon footprint caused by an astounding number of plastic bottles a year.

Sometimes, in a world full of constant distractions, it’s too easy to forget how important it is to drink clean water. Luckily, under-sink water filters can help remedy your in-house water situation.

Considering consumers will likely be looking at multiple under-sink models to fulfil their needs, we’re narrowed down the most important factors to consider when choosing the proper under-sink filter. From contaminants removed, certifications, prices, warranties, certifications, water pressure, and installation, here’s everything you’ll want to know before buying your under-sink water filter.


OptimH2O Reverse Osmosis Claryum Under-Counter Water Filtration System with Chrome Finish Faucet
  • Total approx 5 year cost: $1,150
  • Flow rate: 0.5 gpm
  • Warranty: 2 year
See on Amazon

Best overall (non RO)

Aquasana AQ-5200
  • Total approx 5 year cost: $655
  • Flow rate: 0.5 gpm
  • Warranty: 1 year
See on Amazon

Runner up

  • Total approx 5 year cost: $740
  • Flow rate: 0.5 gpm
  • Warranty: 1 year
See on Amazon

Best for lead removal

Brondell Coral
  • Total approx 5 year cost: $420
  • Flow rate: 0.5 gpm
  • Warranty: 1 year
See on Amazon

Best no faucet under-sink filter

3M Aqua-Pure 3MFF100
  • Total approx 5 year cost: $705
  • Flow rate: 2.5 gpm
  • Warranty: 1 year
See on Amazon

Best cheap (but worthy)

  • Total approx 5 year cost: $400
  • Flow rate: 1.5 gpm
  • Warranty: 1 year
See on Amazon

What to look for in an under-sink water filter

Contaminants removed

Contaminants Certification to remove Products
Harmful contaminants: Lead, Asbestos, Arsenic, Mercury, Cysts, VOCs etc.* NSF 53, 58 Aquasana OptimH2O, Aquasana AQ-5200, APEC RO-PH90, Brondell Coral, 3M Aqua-Pure 3MFF100, Filtrete Maximum
Chlorine and Chloramines NSF 42 Aquasana OptimH2O, Aquasana AQ-5200, Brondell Coral, 3M Aqua-Pure 3MFF100, Filtrete Maximum
PFAs P473 Aquasana OptimH2O, Aquasana AQ-5200
Emerging contaminants NSF 401 Aquasana OptimH2O, Aquasana AQ-5200

*Check with product performance data sheets if you are concerned about a particular contaminant.

The top factor in choosing an under sink water filter is the number of contaminants removed, or how much of a specific contaminant a filter can remove.

If you are worried about the quality of your water and are unsure of what is in it, then you should aim for the best product available that eliminates the most contaminants possible. If you know exactly what contaminants are in your local water source, you can be more precise in your purchase.

For example if your local water source has trace amounts of lead in it, then you will want a water filter that can filter over 99% of lead, and other contaminants may not be as much of a worry for you. Under-sink water filters commonly remove the following contaminants: chlorine, iron, lead, asbestos, TDS (total dissolved solids), bacteria, cysts, and fluoride along with many others.

We recommend finding out what contaminants are in your water source by checking your local Consumer Confidence Reports (CCR), or getting your private well water tested. This is because different systems remove different contaminants so choosing your product should be based on your specific needs. Here are our main contaminants of concern and reasons why:

There are also many other contaminants (too many to list), but if you get a quality under sink water filter you can do your best to protect yourself and your loved ones from any adverse health effects.

Because of the potential for lead to get into your water through leaching from old pipes after it leaves the water treatment facility, we do not recommend any products that have not been certified to reduce lead.


To be sure filter systems are filtering out what they claim to, look for products that have NSF (National Sanitation Foundation) or WQA (Water Quality Association) certifications that are the gold standards in the USA for water filtration systems. NSF and WQA marks are meant to provide proof that a product was “impartially reviewed to established standards or guidelines,” states the NSF.org website.

NSF and WQA marks also confirm that product labels and their claims have been objectively verified by a trusted third party and demonstrate a company (or organization’s) commitment to quality, compliance, and safety. The mark, which is recognized in more than 180 countries around the world, has varying associated numbers that range from the automotive industry, retail products, lab equipment, nutritional products, sustainability, and of course, water, wastewater, and food safety.

For under-sink water filters, look for the following certifications:

  • NSF 42 – Is certification to reduce mainly aesthetic or non-health related issues. These include chlorine, taste and odor, iron, manganese, and zinc.

  • NSF 53 and/or NSF 58 – Are certifications to reduce or eliminate contaminants that have known negative health effects. NSF 53 products have a carbon filter and can reduce contaminants to various degrees depending on the quality of the filter.

    These contaminants include heavy metals (e.g., lead), Cryptosporidium, Giardia, pesticides, herbicides, benzene, MTBE, radon, trihalomethane, and PCBs. NSF 58 refers to reverse osmosis (RO) membrane filters, which can remove perchlorate, fluoride, nitrate, nitrite, radium, bacteria, cysts, and heavy metals. It is important to note that carbon filters and RO systems have many crossovers, but they do not filter out all of the same contaminants, as such they can be used in conjunction with one another in the same system.

  • NSF 401 – This certification is for new and emerging compounds, mainly as a result of pharmaceuticals, herbicides, pesticides, chemicals, flame retardants, and detergents being found in tap water that were previously not present.

  • NSF P473 – Certification to reduce PFAS, including PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoate). To make this claim the product must be below to EPA healthy advisory limit of 70 parts per trillion.

Look for multiple certifications when searching for a water filter, and make sure they line up with the contaminants you either know, or suspect are in your water source.

Best overall (Reverse Osmosis)

NSF: 42, 53, 58, 401, P473
Price: 208.99 (Amazon)

After getting through our top two factors in choosing an under sink water filter, we wanted to introduce you to our top-rated product. It ticks a lot of boxes, and to be our top choice it had to.

OptimH2O Reverse Osmosis Claryum Under-Counter Water Filtration System with Chrome Finish Faucet


  • Removes 99% of harmful contaminants including arsenic, lead, PFAS, and bacteria

  • Certified to NSF 42, 53, 58, 401 + P473

  • Improves taste and odor

  • Compatible with well water systems

  • Large filtering capacity

  • RO + Carbon + Claryum + Remineralization

  • Value

  • 2 year warranty


  • Slower flow rate than some under-sink models

Buy from Amazon

The Aquasana OptimoH2O has impeccable filtering, here are some of the main contaminants it can reduce or remove:

  • Lead: 96.6%
  • Chlorine: 97.66%
  • Arsenic: 97.6%
  • Cysts: >99.99%
  • Emerging compounds: >94.2%
  • PFAS: 96%
  • Asbestos: 99%

Performance data sheet

Being tested and certified by the NSF to NSF/ANSI standards 42, 53, 58, 401 + P473 to remove more than 80 contaminants, it is one of the most comprehensively certified systems available. In comparison, more than 50% of under-sink water filters on the market do not have any certifications adhering to NSF standards, and this has 5 of them.

The Aquasana OptimoH20 utilizes a reverse osmosis membrane to reduce 14 impurities, and a patented Claryum filtration method to reduce 60 other contaminants. The filtering process is finished by remineralizing the filtered water with healthy amounts of calcium, magnesium, and potassium, which provides alkaline, pH balanced water. Here is a breakdown of the 3 stages + remineralization:

  1. Carbon filtration: Reduces organic chemicals, VOCs and MTBE
  2. RO membrane filtration: Filters out dissolved solids smaller than 1 micron including heavy metals.
  3. Claryum filtration: Targets chlorine and chloramine (aesthetic issues)
  4. Remineralization: Healthy amounts of minerals are absorbed back into the purified water to raise the pH level to a balanced level.

The Aquasana OptimoH20 is also our best under-sink water filter for well water. With over 13 million American households relying on well water for drinking, it’s important to keep the water you drink from your well clean. Well water can have microorganisms such as bacteria, viruses and parasites in it, as well as nitrates, heavy metals, organic chemicals, radionuclides, and fluoride.

Essentially anything that can contaminate water can be in a well water source depending on where you live. So you’ll want to get a powerful filtering system to cover a variety of needs, especially for bacteria, from our research only 29% of under-sink water filters offer bacteria reduction. The Aquasana filters 99% of bacteria, putting it in the top 1%.

The filter life for the Aquasana Optimo is solid with the Carbon and Clayrum filters needing to be replaced every 6 months or 365 gallons, which will cost you ~$65. The RO membrane needs to be changed every 1-2 years according to Aquasana and will cost ~$60, and the remineralizer costs ~$30 and needs changing once a year. If you use less water in your home than you’ll only need to replace the RO membrane once every 2-3 years.

The total system and running cost (filter replacements) for 5 years will cost approximately ~$815, which is an amazing deal considering you are getting the best under-sink water filter on the market.

The system can give you up to 32 gallons per day, to apply this practically, men require about a gallon of water a day, and women require just under 3/4 of a gallon a day according to the Mayo Clinic. So if you take this into account, it can provide enough drinking water for a large family.

Look for filters that have to be changed less often. It may not seem like a hassle but if you have to change your under sink filter every 2 or 3 months, it can become irritating, and the risk of banging your head while fiddling around under your sink is real. So, look for filters that only need replacing every 6 months or more.

To ensure this you will want a carbon or sediment filter product with at least 300 gallon filtering capacity as this will typically last up to 6 months.

If you have a reverse osmosis system you will likely have carbon filter replacements that last 6 months, and a reverse osmosis membrane that will need to be replaced annually or can last as long as 5 years in some cases.

For reference, if you are a family of 4 and you each drink the recommended half gallon-gallon of water per day you will consume 60-120 gallons a month, and 360-720 gallons in 6 months.

If you live alone you will consume ¼ of this amount (90-180 gallons). Filters may need to be changed sooner if you consume the amount of water a filter is recommended for, this is to avoid filters becoming clogged with adsorbed contaminants, which leaves no room to capture more.

Compared to other water filters, under-sink products tend to be on the slightly higher end of pricing. They are not nearly as expensive as whole house systems however.

There’s a range of enhanced capability models that are more expensive but low-cost systems usually stick around the $100 threshold.

Under-sink filters that remove chlorine or aesthetic issues will run you about $100.

Higher-quality systems that are certified to remove harmful contaminants such as lead range from $150 to $300. Some premium under-sink filters are on the market for as much as $500, but you don’t need to spend this much for a quality product.

We recommend you stay between the $150 to $300 range, and also look at the ongoing filter replacement costs of your filter, trying to save $50 dollars on a system could cost you hundreds more if it has higher filter replacement costs than another system.

What makes under sink water filters different?

Truly on-demand

Thanks to the way they combine with your sink, these filters are sleek and highly versatile. A dedicated filter faucet makes it easy to fill glasses or pots for cooking with one hand.

Unlike pitcher filters, most models don’t use a reservoir—meaning there’s no annoying wait for water to feed through the system, RO systems can be an exception, but their holding tanks should be large enough that you never have to wait for water.

A step up in filtering power

Some under sink filters at lower price points use the same filtering mechanism as other kitchen designs. But the majority employ larger, more powerful filtration methods, harnessing mains pressure to push tap water through dense carbon blocks or reverse osmosis membranes (see below).

This leaves tap water purer, better tasting, and potentially safer than when using a pitcher or faucet-mounted solution.

Style considerations

Most under-sink models either send water directly through your pre-existing faucet or through a secondary tap, mounted around your sink. Here, many under-sink filters are supplied with their own water dispensers—but you don’t necessarily need to use the dispenser that comes out of the box. Sourcing your own faucet for an under-sink filter can add to the look of your kitchen, making the filter seem more integrated with your other appliances.

Best overall (non RO)

Aquasana coming through with another banger! Okay, we’ll try and contain our excitement a bit, but this system rivals it’s bigger OptimoH2O brother. It has all of the certifications that it does, minus one, which is only for RO systems.

If you don’t want an RO system, then this is a top choice. Certified to NSF/ANSI standards 42, 53, 401, and P473 it has great filtering capabilities.

Aquasana AQ-5200


  • Removes 99% of harmful contaminants including arsenic, lead, PFAS, and bacteria

  • Improves taste and odor

  • Certified to NSF 42, 53, 401 + P473

  • Easy to install

  • Great tasting water

  • Compact, takes up very little pace

  • No leakage


  • None

Buy from Amazon

The Aquasana 2-Stage AQ-5200 system uses Claryum technology in its two-stage filter to eliminate 99% of contaminants that are most commonly found in municipal wells while leaving in essential minerals that are good for you, like calcium and potassium. Here are some of the contaminants that the AQ-5200 can reduce:

  • Lead: >99.4%
  • Chlorine: 97.66%
  • Cysts: >99.99%
  • Emerging compounds: >94.2%
  • PFAS: 96%
  • Asbestos: 99%

Performance data sheet

What really stands out, the Aquasana 2-Stage system has the most certifications we have seen from the NSF for one single under-sink non-RO product. Essentially, you know you’re getting good, pure, and clean water with every drip of the faucet.

Through this system, the water is filtered through an ion-exchange which filters mercury, lead, and other metals while simultaneously preserving the water’s content of minerals so drinkers are still getting potassium, magnesium, and calcium with every glass.

This under-sink filter comes with one set of double filters that provides 600 gallons of purified water at a rate of 10 cents a gallon, significantly less expensive than the price of plastic water bottles sold at stores.

As mentioned before, filtration systems aren’t only saving consumers money but are doing a substantial job at reducing the earth’s carbon footprint.

Once the system starts to beep, the filters need to be replaced. Expect this to happen every six to eight months, depending on the frequency of use.

At $139.99, the Aquasana AQ-5200 comes at a fair price. Its filters cost $59.99 and need to be replaced every six months, which is not extraordinary.

The Aquasana is very small and compact which saves a good amount of space under the sink and can fit in the vast majority of traditional kitchen sinks.

The environmentally-friendly product comes with a one year warranty and retains beneficial minerals like calcium, magnesium, and potassium. It’s easy to install, maintain, and replace and doesn’t typically require any additional help (sorry, plumbers.)

Some people consider flow rate an important factor when purchasing an under-sink water filter. However, most under-sink water filters come with a dedicated faucet that is installed with the system.

Therefore, most under-sink systems will give you a slower running dedicated faucet whilst maintaining the full flow of your existing kitchen faucet. There are some systems that can be installed and don’t require a separate faucet, these are more rare and most will slow down your water flow rate slightly.

Even though flow rate is not the biggest concern when you’re considering an under-sink filtration system, be sure to look for products with at least a minimum flow rate of 0.5 gallons per minute (gpm) for typical under-sink models.

If you want a plumbed in fixture without a dedicated faucet you’ll likely want a faster flow rate, so it doesn’t slow down your faucet every time you turn on your tap. Average water pressure of a faucet is 2.2 gpm, so look for a product rated from 1.5 to 2.5 gpm to avoid your flow rate being noticeably affected.

For Reverse Osmosis systems, their filter rate is slower as they have a more rigorous filtering process. That is why most systems have a holding tank, so filtered water is ready to use right away. We recommended for RO systems you look at gallons per day (gpd), with systems 10 gpd.

PSI is another factor to look for, the majority of under-sink water filters require at least 40 psi water pressure to be effective. The highest psi a house should possibly have is 80 psi, and the average house is 50 psi. So look for a product that can handle between the ranges of 40-80 psi. If your house has low water pressure (<40 psi), then we advise to look for an under-sink filter with a permeate pump, that will boost the water pressure making a filter viable.

In terms of space, if you live in a small apartment, you might want to consider a compact unit of under-sink filters. Obviously, since they’re installed beneath your sink, these types of filters are pretty good when it comes to saving space versus on-top alternatives. If space is limited, even beneath the sink, some countertop models are available. The tape measure will be your best friend here, so measure your space and compare it to product dimensions.

When considering water waste, some reverse osmosis systems have high waste to filtered water ratios. For RO systems, you’ll want to aim for a 3:1 or 1:1 ratio.

Having a warranty is a good option to consider when purchasing an under-sink filter. If your product ever turns out to be faulty — which happens — you won’t have to deal with the headaches of finding a new one and manufacturers will provide you with a replacement.

The average warranty for under-sink water filters is 1 year. So we’d recommend purchasing a warranty that is at least one year, and more ideally greater. Generally, the longer the warranty, the more confident in their product manufacturers are.

While some systems are more difficult to install than others, user-friendly systems that are easy to install might be easier on your state of mind. All of the products listed can be installed by consumers.

Some under-sink filters provide easy-to-follow and step-by-step instructions with the goal of making it as easy as possible to go from store to function as soon as possible. Obviously, if troubles ever persist, you can call a plumber to help your installation (We’ve all been there).

Listed above are the 2 products we believe cover most under-sink water filtering needs. Here are more of our top choices that cover more specific needs:

Runner up

Our runner up choice is a strong reverse osmosis filter, but falls short of the Aquasana H2Optimo and Aquasana 2-Stage.



  • Filtering capability

  • WQA Gold Seal certified to NSF/ANSI 58

  • Super capacity filters (long life)

  • Affordable filter replacements

  • Suitable for most houses

  • 90 GPD capacity

  • Remineralization

  • Large holding tank


  • Only certified to one NSF/ANSI standard

Buy from Amazon

The APEC RO-PH90 performance data sheet is not readily available, however, we got in contact with APEC and they provided it upon request. Here are the contaminants it reduces:

  • Lead: 96.8%
  • Fluoride: 93.8%
  • Arsenic: 99%
  • Chromium: 99%
  • Copper: 98.4%
  • Turbidity: 98.7%
  • Barium: 98.8%
  • Cadmium: 98.3%
  • Radium: 98.8%
  • Selenium: 97.8%

The WQA has certified this product to NSF/ANSI standard of 58 so you know you are getting a quality under sink water filter that has been through rigorous independent testing. 

This is a 6-stage filtration system, meaning it has 6 different filters. Each stage has its own unique filtering capability: 

  1. Sediment filter: removes dust, particles, and rust.
  2. Carbon block filter: removes chlorine and chloramine and any associated odor and taste
  3. Carbon filter: removes VOCs and other common chemicals
  4. Reverse osmosis membrane: filters harmful contaminants including arsenic, lead, fluoride, chromium, radium and more.
  5. Coconut shell refining carbon: removes any residual taste from RO tank
  6. Calcium carbonate remineralization: increase pH level by adding calcium carbonate mineral back into the water.

That’s a lot of filters! Fortunately these filters can be purchased as a complete set. However, like most RO systems the filters need to be changed at different times, as some filters have shorter lifespans. The shortest is 1 year, and the longest is the RO membrane which lasts 3 to 5 years (depending on use). So you won’t be changing filters often. 

The price for 6 filter replacements is around $150, so it’s a great bang for your buck. The majority of under sink filters/reverse osmosis need filter changes at least once every 6 months, so this system is a step above. 

This system is suitable for houses with water pressure between 40-85 psi. This will cover the vast majority of homes water pressures, the average psi of homes is 50 and the maximum is 80. 

This model has a 4 Gal. storage tank, so when that is full the dedicated faucet flows freely. And the storage tank begins to refill as water is used.  The system can filter 90 GPD. For reference, it is recommended to drink ½ to 1 gallon of water a day per person, so if you have a large family it has you covered (and more). 

For the price of just under $350 this comprehensive system has all your drinking needs covered. The 5 year cost for this system including purchase is approximately ~$900.

Its ongoing costs (filter replacements) are low, so this system will be cheaper than most other under sink/reverse osmosis systems long term. 

The APEC comes with a 1-year warranty and lifetime technical support for peace of mind.

Best for lead removal

The Flint Michigan water crisis grabbed the world’s attention. Making national and international headlines as a result of aging lead pipes leaching the heavy metal neurotoxin into the water supply of over 100,000 Michigan residents. It showed that in one of the most advanced countries in the world, you can get irreversible damage simply by having a glass of water.

Brondell Coral


  • Lead reduction

  • Value

  • Taste and smell

  • Easy installation and filter changes

  • LED filter change indicator light 

  • Multi-stage filtration

  • 1 year (600 Gal.) filter life

  • NSF 42, 53, & 372 certified


  • Does not reduce bacteria, iron, or fluoride

Buy from Amazon

If you want to make sure there is not lead in your drinking water, and this is all that matters to you, then the Brondell Coral will remove 99.7% of lead. It is also certified to reduce over 60 other contaminants. Here are a few:

  • Lead: >99.7%
  • Chlorine: 98%
  • Cysts: 99.99%
  • Asbestos: 99.96%

Performance data sheet

It’s certifications include WQA certification to NSF 42 and 53, so it will remove both aesthetic issues as well as harmful contaminants. It also has an NSF 372 certification, which means that the product has been made using “lead-free” materials. It’s certified to the equivalent in Canada with a certification of CSA B483.1.

The filter life for the Brondell Coral  is 1 year or 600 Gal., which is great considering the average filter life for under-sink filters is around 6 months. It has a flow rate of 0.5 gpm which should handle all your drinking needs, in a minute that’s one person’s suggested water intake for an entire day. To filter the water the Brondell Coral has three stages of filtration: 

  1. Sediment filter
  2. Pre-carbon filter
  3. Carbon filter

These filters reduce physical, chemical, and biological contaminants that is system is certified for, including:

  • Bad taste and odor
  • Heavy metals (e.g., lead and mercury)
  • Commercial contaminants (MTBE)
  • Herbicides
  • Industrial chemicals
  • Pesticides
  • TDS
  • VOCs

The price for this system is very fair, coming in below $150 dollars. Filter replacements will cost you $69.99 (for all three). The total 5 year running cost for the system would cost approximately $430 dollars. That’s a great deal for some of the best lead and chlorine filtration out there. 

This Brondell product is easy to install and has a double O-ring filter seal designed to prevent leaks. It is suitable for all households as it has a maximum psi rating of 100 psi and minimum of 35 psi.

Changing filters is easy with it’s twist and lock design, so no tools are necessary. It even has a filter change reminder, so you won’t have to keep track yourself. The one year warranty included is about average for under-sink filters.

Best no faucet under-sink filter

This system has a capacity of 6,000 gallons but it’s known for being the ideal option for customers who don’t want a dedicated faucet. The system is added directly to home’s water line so it’s perfect if you don’t want a dedicated faucet.

3M Aqua-Pure 3MFF100


  • Certified by NSF 42 and 53

  • High capacity

  • Fast flow

  • Easy to install


  • You may need additional parts after installation

  • Expensive filters

Buy from Amazon

It reduces particulate, chlorine taste and odor, lead, parasitic protozoan cysts, and select volatile organic compounds (VOCs) such as benzene and p-Dichlorobenzene. Here are the main contaminants the 3M Aqua-Pure reduces:

  • Lead: 99.6%
  • Chlorine: 97.4%
  • Cysts: >99.99%
  • Particulate Class I: 99.4%

The 3M brand has been manufacturing water filtration products for over half a decade and most of their products sport the NSF 42 and 53 certifications. 

Filters are a bit expensive at $120.42 and the overall price is mid-to-high range at $223.52.

Because it doesn’t require a separate faucet, it’s very easy to install but requires some general household tools during setup. Since there’s no need to alter the counter, however, installation can be very quick and cost-efficient.

Best cheap (but worthy)

We understand the importance of using money effectively, especially in the current state of the world where job security is less stable than it ever has been in many of our lifetimes.

The standout point for the Filtrete Maximum is that it costs only $53.99, which is the cheapest option we have found for being able to reduce both Chlorine, Lead, and some other harmful contaminants.


  • Certified by NSF 42 and 53

  • Affordable

  • Reduces lead

  • Reduces chlorine

  • Fast flow


  • Does not reduce a wide range of contaminants

Buy from Amazon

This is a perfect choice if you are looking to affordably target some contaminants and don’t need more brod filtering capabilities. The total five year cost of $400 is the lowest on our list, so not only are you up front costs cheap, but so are the filter replacements. 

This model also has a high flow rate, as it is plumbed directly into your cold water line it is certified to flow at 1.5 gpm, so it will slightly reduce the average flow rate of most homes, which is 2.2 gpm. But you should not notice a significant change. 

Here are some of the main contaminants the Filtrete Maximum reduces:

  • Lead: >99.3%
  • Chlorine: >97.4%
  • Cysts: >99.95%
  • Particulate Class I: >99.9%

Performance data sheet

How do under sink filters remove contaminants?

Carbon block filters

Unlike most point-of-use water filters, under sink systems are less constrained by the need to be small or portable. This means they’re able to employ more rigorous, powerful types of filtration mechanisms, such as reverse osmosis and carbon block filters.

Reverse Osmosis

Under sink filter pros

  • Seamless filtered water. These filters stake a good claim for being the easiest point-of-use designs available. Not only do they free up space on your kitchen counter, but they don’t require manual filling. Also, their larger size means that cartridge replacements are only necessary every six months, as opposed to around half that for pitcher and faucet filters.

  • Efficient filtering. Unlike most types of kitchen filters, under-sink systems take advantage of the water pressure from your mains system. They use this pressure to push water through the filter, instead of relying on a gravity reservoir. This allows under sink filters to use denser cartridges, which can take on a greater range of pollutants.

Under sink filter cons

  • Installation. Many under sink models can be installed by the homeowner—but there’s also a good chance you’ll need the help of a professional if you aren’t confident in your DIY skills. Be sure to consider any time and costs this may involve. Installation can be less a matter of adapting your under sink plumbing, than making alterations to your countertop. If you have a bespoke counter, alterations may require the services of a stonecutter or carpenter.

  • Kitchen adjustments. On the countertop point, drilling holes in a counter surface may immediately rule out under sink filters for renters and those living in shorter-term accommodation. Reverse Osmosis filters also take up significant cupboard space under the sink, which is hot a huge deal, but worth thinking about.