The 10 Best Under Sink Water Filters: Reviews & Ultimate Guide

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This is our review of the best Under Sink Water Filters of 2021.

We reviewed several under sink water filters and found out that the Waterdrop G3 Reverse Osmosis Under Sink Water Filter System is the best one.

We know that it isn’t easy to select an under sink water filter, as you need to understand the different types, the main factors to consider when buying, the pros and cons of each model, and so on.

To make this task easier for you, we combined our expertise on the topic plus some extensive research, to put together a comprehensive under sink water filter guide and a review of the best models available in the market, for different situations.

In this article, you will find out the best under sink water filters available, their pros and cons, an explanation of why they are better for specific situations, and a detailed buying guide to provide you all the relevant information to choose the best under sink water filter for you.

Let’s get started!

Our Top Picks for Best Under Sink Water Filters

10 Best Undersink Water Filters Reviewed

After investing our time researching and reviewing several undersink water filters, we identified the 10 best options for different purposes.

We’ve invested the time so you don’t have to:

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  • Best for: Overall (RO)
  • Type: Reverse Osmosis Under Sink Water Filter
  • Dimension: 18.07 x 5.52 x 17.52 inches
  • Weight: 31 pounds
  • Filter Longevity: Carbon Filter: 6 months, Post Activated Carbon Filter: 12 months, RO Membrane: 24 months
  • Remineralization: Optional bundle

If you are looking for a Reverse Osmosis under sink water filter, the Waterdrop G3 Reverse Osmosis system is the best overall and we highly recommend it! It’s easy to install and set up, has a compact and modern design that allows you to save space, it’s efficient with only a 1:1 waste water ratio, and comes with modern smart monitoring capabilities. 

The Waterdrop G3 RO Under Sink System filters up to 400 GPD, and it’s able to remove several contaminants through a 7-stage filtration process, such as chlorine, sand, rust, solids, bad taste and odors, and other impurities. It also reduces TDS, limescale, heavy metals, bacteria, viruses, and more than 1,000 other harmful contaminants.

Another set of features that we love are monitoring capabilities, as the faucet has a LED ring that glows with different colors to let you know in real-time the status of your water filters. It also has an LCD panel that displays in real-time the TDS level of the water. The system comes with an automatic flushing capability that self-cleans the system when needed, without manual intervention.

The compact and nice-looking design of the Waterdrop G3 RO system saves space and makes it not only aesthetically pleasing but also makes the installation process easier.

Like any RO system it produces waste water, but the Waterdrop G3 RO is highly efficient with a waste water ratio of 1:1, which means it only wastes one gallon of water for each gallon of filtered water, better than most of its competitors.

The Waterdrop G3 RO under sink system is NSF 58 and 372 certified, meaning that the NSF 58 is for TDS reduction, ensuring that it’s able to remove most of the contaminants of the water, including heavy metals, fluoride, limescale, etc., and NSF 372 ensures that it’s a lead-free material system.

Pros:

  • Tankless, with a great design
  • Smart filter life indicator
  • TDS water quality monitoring
  • NSF certified
  • Good waste water efficiency
  • Great daily water output
  • Internal pump
  • Space-saving

Cons:

  • Price
  • Slow water flow
  • Some customers mentioned it may be required to run some water until the TDS drops to an acceptable level
  • Best for: Overall (Conventional)
  • Type: Conventional Under Sink Water Filter
  • Dimension: 12 x 4.25 x 9 inches
  • Weight: ‎6 pounds
  • Filter Longevity: 6 months or 600 gallons

The Aquasana AQ-5300 under sink water filter is an excellent choice for a conventional under sink water filter, as it combines an affordable price with the ability to remove several harmful contaminants, and it is NSF certified.

The best feature for us is the NSF certifications, as the certification NSF 42 ensures that this filter can remove chlorine and bad tastes and odors, the certification NSF 53 is against volatile organic chemicals (VOCs), lead, and Cryptosporidium, the certification NSF 401 is against herbicides, pesticides, detergents and pharmaceuticals, and the P473 against PFOA (Perfluorooctanoic Acid) and PFOS (Perfluorooctane Sulfonate).

And while it removes up to 77 harmful contaminants, the Aquasana AQ-5300 under sink water filter has a patented filter that keeps healthy minerals like calcium and magnesium in the filtered water, to ensure that you have clean and tasty water to drink.

It has a higher flow rate than most of its competitors, being able to filter through half a gallon per minute, which is great if you don’t have time to wait for filtered water.

Another nice feature of the Aquasana AQ-5300 is how quick and easy it is to replace the filters, as you only have to twist off, remove the old filter and replace it with the new one, and twist on again. And you only will need to change the filter every 6 months.

Pros:

  • NSF certified
  • Easy to install
  • Easy to change the filters

Cons:

  • Filter’s lifespan
  • Some customers complained about leaks after some time
  • Best for: Overall (Simple)
  • Type: Simple Under Sink Water Filter
  • Dimension: 4.5 x 4.5 x 15 inches
  • Weight: 7.89 Pounds
  • Filter Longevity: 5 years

The CuZn UC-200 Under Counter Water Filter is a great choice for a simple under sink water filter, as it combines in a single package a powerful water filtration system, an easy to install device, and a durable filter.

And this last feature is probably the one that sets apart this water filter from the competition, as it will last 5 years or 50.000 gallons of water without the need to change filters. And CuZn provides warranty replacement if it stops working sooner, so you will have clean water without extra cost for a long time.

The CuZn UC-200 under sink filter has a 3-stage filtration process that removes the most common contaminants in municipal water such as heavy metals (like lead and mercury), chlorine, sediments, herbicides, pesticides, VOCs, etc. And it uses a bacteriostatic filtration system which means that it won’t grow bacteria or mold like other systems.

While it removes contaminants, it is not as powerful as other under sink water filters like Reverse Osmosis systems we present on our list, as it won’t lower TDS, or deal with contaminants from well water, or deal with hard water, making it a good choice for municipal water filtration only.

Another great feature of the CuZn UC-200 system is how quick and easy it is to install, and you probably can do it in less than 5 minutes as it only needs to be connected directly to the cold water line, as this type of system won’t need an additional faucet.

Pros:

  • Filter longevity, up to 5 years
  • Simple to install
  • 5-year warranty

Cons:

  • A large model that may not fit under sink in some cases
  • Not designed to reduce TDS or to deal with well water
  • Best for: Value (RO)
  • Type: Reverse Osmosis Under Sink Water Filter
  • Dimension: 15 x 8 x 18 inches
  • Weight: 20 pounds
  • Filter Longevity: 6 months
  • Remineralization: Yes

The iSpring RCC7AK 6 Stage Reverse Osmosis System is the best choice for value if you are looking for a Reverse Osmosis under the sink system. It is a certified RO system that offers a 6-stage water filtration process with remineralization at a competitive price.

This NSF certified system is capable of removing up to 99% of the most common contaminants from the water, and it also comes with an alkaline remineralization filter that restores the healthy minerals removed by the RO membrane, which balances the pH of the water making it less acidic, and improves the taste.

While installing a RO under sink system is not as easy as installing a conventional or simple under sink system, several customers mentioned that it was straightforward to install this under sink system, with good support of physical and online manuals, videos, and phone support.

Another nice feature that we like in the iSpring RCC7AK 6 Stage System is that the 1st stage housing is transparent, which means that you can visually check the sediment filter and know when it needs to be changed.

Our least favorite thing about this system is its low efficiency, as it will produce 3 gallons of waste water for each gallon of filtered water. If this is an issue for you, you can always choose a similar model that comes with a permeate pump, the iSpring RCC7P-AK Boosted Performance Under Sink 6-Stage Reverse Osmosis System, that improves the waste ratio to just 1:1.5.

Pros:

  • Powerful contaminant removal
  • NSF and WQA certified
  • Remineralization
  • Nice looking faucet included

Cons:

  • Low waste water efficiency
  • Some customers complained about leaking
  • Best for: Value (Conventional)
  • Type: Conventional Under Sink Water Filter
  • Dimension: 6 x 15 x 12 inches
  • Weight: 14 pounds
  • Filter Longevity: 12 months

The APEC WFS-100 3 Stage Under Sink Water Filter is a very popular filter and a good choice for value in the category of the conventional under sink water filters, offering a good filtration system with an affordable price, and with filters that last longer than usual minimizing the recurring cost associated with it.

While this 3-stage filter removes some of the common water contaminants like dust, rust, chlorine, bad taste and odors, VOCs, chemicals, etc. and keeps the healthy minerals, it does not remove lead and does not reduce TDS, which can be a showstopper for some situations, making it more suitable for municipally treated water.

This is a tankless system that can deliver a fast flow of water with good pressure instantly, without the need to wait a long time to fill a cup of water.

Another great feature of the APEC WFS-1000 Under Sink Filter is the longevity of its filters, which will last 12 months, twice the duration of other models.

Pros:

  • Filter’s longevity
  • Does not remove healthy minerals
  • Nice quality faucet included

Cons:

  • Does not remove lead and TDS
  • Some customers complained about the installation process
  • Best for: Value (Simple)
  • Type: Simple Under Sink Water Filter
  • Dimension: 5 x 5 x 13.5 inches
  • Weight: 4.2 pounds
  • Filter Longevity: 6-8 months

The Frizzle MK99 Under Sink Water Filter is the best value choice for a simple under-sink filter because it is an NSF tested water filter capable of removing the harmful contaminants of your water and leave the beneficial and essential minerals, it is an easy to install system and comes with a great price.

The NSF 42 ensures that this under sink filter is capable of removing chlorine, taste and odors, and the NSF 53 ensures that it removes lead, arsenic, fluoride, etc. Apart from these contaminants, this 2-stage water filter is capable of removing 99.9% of the 58 common harmful contaminants from your water, but leaves the beneficial minerals in it (like calcium, magnesium, and potassium), offering tasty and healthy water.

The Frizzle MK99 Under Sink Water Filter System is quick and easy to install, and it is compatible with your cold water line, whatever your sink has a 3/8″ or a 1/2″ feed water valve.

It is also quick and easy to replace the filters, and the system is designed to be able to complete this task in less than 3 minutes. It has an automatic water shut-off so you don’t need to shut off the water supply to replace the filter, just twist the device and change the filter without the need for any tools.

The filter longevity is in line with other models, and the supplier recommends changing it every 6 to 8 months for better filtration, but they can be used for up to 2 years.

Pros:

  • Price
  • NSF tested
  • Good at removing contaminants
  • Easy to install and replace filters

Cons:

  • Some customers complained about low water pressure
  • Best for: Good Choice (RO)
  • Type: Reverse Osmosis Under Sink Water Filter
  • Dimension: 16 x 5.25 x 17.5 inches
  • Weight: 27 pounds
  • Remineralization: Yes

The APEC Water Systems ROES-PH75 Essence Series is a great under sink RO system, that purifies water through a 6-stage filtration process but includes a remineralization process to add back the healthy minerals to the water, and comes with a flow restrictor and automatic shut-off valve, all of this at an extremely competitive price.

The APEC Water Systems ROES-PH75 Essence Series uses a 6-step filtration process to ensure the removal of the common harmful water contaminants, and on the last stage minerals lost in previous stages are added back to the filtered water, raising the pH, making it tastier and healthier.

Another feature that differentiates this system is the fact that it comes with a 2 year extended manufacturer’s warranty, with registration.

The only thing we don’t like about this RO under sink system is the waste water efficiency of 1:3, wasting 3 gallons of water for each gallon of purified water, but it is a typical efficiency amongst RO systems.

Pros:

  • Remineralization
  • Easy connection to refrigerator
  • 2-year extended manufacturer’s warranty
  • WQA certified
  • Filters longevity

Cons:

  • Low waste water efficiency
  • May require an additional pump
  • Some customers mentioned the faucet quality
  • Best for: Good Choice (Conventional)
  • Type: Conventional Under Sink Water Filter
  • Dimension: 10.63 x 4.33 x 12.6 inches
  • Weight: 4.4 pounds
  • Filter Longevity: 6 to 12 months

The iSpring CU-A4 Under Sink Water Filter is a good choice if you are looking for a conventional under the sink water filter, as it comes with a 4-stage filtration process that includes an ultra filtration stage (with a membrane with a pore size of 0.01-micron) to ensure the removal of most common and harmful water contaminants like rust, sand, VOCs, chlorine, lead, arsenic, etc. without removing the beneficial minerals from your purified water.

The CU-A4 Under Sink Water Filter is really simple to install and to change the filters, and it comes with push to connect fittings and color-coded tubes to simplify the installation process, and twist on and off filter cartridges to smooth the filter replacing process.

Like most conventional under sink water filters, this system also comes with an additional faucet, in this case, a premium chrome finish faucet that looks great in a kitchen sink.

And while the CU-A4 is not NSF certified, the manufacturer mentions that the system is independently tested to comply with NSF and ANSI standards for water quality and safety.

Pros:

  • Does not remove healthy minerals
  • Tested to NSF standards
  • Nice quality faucet included

Cons:

  • Does not remove fluoride and TDS
  • Some customers complained about the installation process
  • Best for: Good Choice (Simple)
  • Type: Simple Under Sink Water Filter
  • Dimension: 3.6 x 3.9 x 16.7 inches
  • Weight: 4 pounds
  • Filter Longevity: 16.000 gallons (about 2 years)

The Waterdrop 15UA Under Sink Water Filter is a good choice for a simple under the sink water filter system, as this easy-to-install system comes with a 4-stage filtration process that includes an ultrafiltration membrane to filter out particles larger than 0.01-microns, delivering pure and healthy water to your family.

This system has the NSF 372 certification that ensures the product is made of lead-free and BPA-free materials, and it is tested against NSF 42 standards to ensure the reduction of chlorine, bad tastes and odors. And through the 4-stage filtration process, also removes other common contaminants such as sediments, heavy metals, chemicals, etc.

The Waterdrop 15UA Under Sink Water Filter is quick and easy to install, and according to the manufacturer, you can do it in less than 3 minutes as you just need to connect it directly to the cold water supply using the push-to-connect fittings.

The filter of this system has a longevity of 2 years or around 16.000 gallons, which is good compared with the competition, and makes this filter a price-competitive option. When it’s time to change the filter, the process is quite easy as the twist-and-lock design allows you to replace the filter in seconds without using tools.

Pros:

  • Price
  • NSF certified
  • UF process that maintains healthy minerals
  • Filter longevity

Cons:

  • Does not remove fluoride and TDS
  • Some customers complained about low water flow
  • Best for: Budget
  • Type: Simple Under Sink Water Filter
  • Dimension: 4 x 6.8 x 14 inches
  • Weight: 3.09 pounds
  • Filter Longevity: 6 months

We had to include the Filterete Advanced Under Sink Water Filtration System in our list, because if you need an affordable, NSF certified, and easy-to-connect simple under sink water filter, this is a nice option.

While not as powerful as other filters we covered in our guide, this water filter has an NSF 42 certification to ensure the reduction of aesthetic or non-health-related contaminants, like chlorine, bad taste and odors, and particulates. With a filter of 0.5-microns, it is also capable of filtering out cysts, sand, rust, and sediments.

The Filterete Advanced Under Sink Water Filter is easy to install, and the manufacturer mentions that you should be able to do it by yourself in less than 30 minutes. Because it doesn’t require an additional faucet, you should be able to install it in different locations of your home.

Changing the filters should also be a quick and easy task, as the system has a smart design that only requires a 1/4 turn for a quick filter change.

The 6-month filter longevity is not as good as other similar models, so even if the initial price is lower than other options, you should consider this when choosing the best under sink water filter for your home.

Pros:

  • Price
  • NSF certified
  • Easy to install

Cons:

  • Filter longevity
  • Some customers complained about the flow rate after a few months

Buying Guide for Undersink Water Filter

Before buying an under sink water filter you should get a clear idea of the important topics regarding this type of purchase, like the main factors to consider, the pros and cons, and how you can install it, and the most frequently asked questions about under sink water filters.

That being said, we put together a comprehensive guide that covers these important topics.

What to Consider When Choosing the Best Under Sink Water Filter

When researching for an Under Sink Water Filter to buy, these are the key features that you should consider:

Type

The type of under sink water filter you choose will have an impact on its cost and difficulty of installation.

The most simple under sink water filters are easy to install, as you don’t need to add an additional faucet to your kitchen sink.

The conventional or regular under sink water filters will require an installation of a specific faucet that will come with the package. This will make the installation more complicated, but you will have filtered water that will flow directly to this new faucet, leaving the other as is. 

Then, there is a special type of under sink water filter, the Reverse Osmosis water filtration system, which is like a conventional under sink water filter regarding installation but combines different filtration stages to deal with several types of contaminants.

Contaminants to Remove

First, you should know which contaminants you need to deal with. You can do this, by checking the CCR of your water provider or by checking the water of your home by yourself, using a water test kit.

Then, with this information in mind, you can check which filters can reduce or eliminate the contaminants in your water. If your water is highly contaminated, you might need a more powerful filter like a Reverse Osmosis filtration system.

Size

You should check the dimensions of the under-the-sink water filter before you buy it, to make sure it fits under your counter. 

Some models are larger than others, and if you go for a RO system it might have a tank, which will need additional space.

Costs: Initial and Maintenance

You should consider the costs associated with buying an under sink water filter before you buy it, to make sure you make the right choice.

Take into consideration not only the initial cost but also the associated costs related to replacing the filters, which you will need to do once or twice a year, depending on the filters.

Certifications

Both NSF or WQA are independent third-party accredited institutions that certify water filters to ensure that they can remove certain harmful contaminants. 

While some brands mention that their products remove specific contaminants, you can only be sure about the products with these certifications, because they were tested by third-party accredited institutions.

Flow Rate

With an under-sink filter, the water needs to go through some filters which will slow down the purified water that will flow from the faucet, which is named the flow rate and it is typically measured in gallons per minute (GPM).

A low flow rate will mean that it can take some time for you to fill a glass of water or a pot of water to cook, which can be problematic if you need lots of filtered water.

Ease of Installation

A regular under sink filter comes with a separate faucet for the filtered water, and if your counter is not already prepared with a pre-drilled hole for an additional faucet, you will need to drill through it, making the installation more difficult.

Read the installation instructions of the undersink filter that you choose to check if it is something that you can do by yourself. Depending on your ability to DIY tasks, you may need external help to install an under sink water filter, so consider this cost into your budget.

Filter Longevity & Capacity

You will need to replace the filter cartridge of your under sink water filter with some frequency, and the longevity of your filter is directly linked to its capacity and the amounts of contaminants in the water.

If your water is highly contaminated, it’s normal that the filter will last less time as it will be more used than normal.

If you select a RO system you need to replace different filters, with distinct frequencies. Usually, the semi-permeable membrane needs to be replaced every 2 years, while the other filters should be replaced once a year.

Waste Water Ratio

This factor is only important if you are looking to buy a Reverse Osmosis under sink water filter, as one of the drawbacks of this type of system is that they generate waste water to produce filtered water. 

This is typically measured as a ratio represented like 1:3, which means that to produce 1 gallon of filtered water, it produces 3 gallons of wastewater.

A 1:3 waste water ratio is common for a typical RO system, but some modern systems are now able to generate much less waste water, some as good as 1:1, combining new technology and permeate pumps to increase water pressure and their efficiency.

Remineralization

Some under sink water filters, and particularly Reverse Osmosis systems, during the filtration process, will remove some important minerals like calcium and magnesium.

Some filters add up minerals on the last stage of the filtration process, remineralizing the water with healthy minerals.

This is not essential if you have a balanced diet, because that is enough to get the magnesium and calcium you need from your food.

What Is an Under-Sink Water Filter?

As the name says, an under-sink water filter is a water filter placed under the sink that filters water on-demand, being able to produce unlimited amounts of water when you turn on the faucet, instead of having to wait some time for the water to be filtered first.

It is a point-of-use (POU) system as it only filters water at the point it’s used, in this case, in the sink faucet. A point-of-entry (POE) system like a whole house water filtration system is capable of filtering the water of the entire house, not only of a specific point.

A conventional or typical under-sink water filter connects to the cold water pipe and sends the filtered water through a specific faucet.

Some simple under-sink water filters won’t come with a specific faucet, as you connect it directly to the sink cold water line and all the water passes through it before it reaches the regular faucet.

The Different Types of Under Sink Water Filters And How They Work

As mentioned before, there are 2 types of under sink water filters, the simple and regular (or conventional), with slightly different ways of working.

Simple Under Sink Water Filter:

This type of under sink water filter is connected to the cold water line and the water is diverted to go through this filter.

This way, all the cold water is filtered when it passes by the water filter, going back to the pipes and flowing by the regular faucet.

The simple under sink water filter is typically cheaper than the conventional one, and it is also simple to install as you don’t need to install a specific faucet.

Conventional Under Sink Water Filter:

The conventional under sink water filter is also connected to the cold water line, but it doesn’t go back to the line.

It is then connected to a specific separate faucet, and all the filtered water goes through this faucet, while the regular faucet only gets regular water that didn’t pass through the water filter.

Usually, the filter cartridge of this type of filter will last longer than the simple under sink filter because not all the water passes through it, only the part of the water that you want to filter.

Undersink vs Countertop Water Filters

Both under sink and countertop water filter systems are good options if you want clean water to drink, but they have some differences that might make one of them better for your specific situation.

On the table below you can understand how they compare against each other:

FeatureUnder Sink Water FilterCountertop Water Filter
FiltrationGood capacity and advanced filtration processesGood capacity and advanced filtration processes
LocationIn a cabinet under the sink, so in a more hidden locationOn the countertop, so it will take some countertop space. Also, because it will be visible, the design will be more important.
SizeLarger than countertop as they will be hidden under the sinkTypically more compact to save countertop space
CapacityBecause they are larger, they typically have more capacity which means the filter cartridge needs to be replaced less oftenDue to their compact design, the capacity is typically lower than an under sink water filter
InstallationMore complex than the countertop water filter, as you may have to drill a hole in your sink to install an additional faucetEasy to install, as you only need to connect an adapter to the faucet.
CostAffordable, but on average more expensive than a countertop water filterAffordable
Reverse Osmosis SystemThere are RO under sink water filter systemsThere are RO countertop water filter systems
POE or POUPoint-of-UsePoint-of-Use

Undersink vs Whole-House Water Filters

You might be wondering if you need an under sink or a whole house water filter for your specific situation.

In the table below you can understand how these systems compare against each other, to make the best choice for you.

FeatureUnder Sink Water FilterWhole House Water Filter
FiltrationGood capacity and advanced filtration processesGood capacity and advanced filtration processes
LocationIn a cabinet under the sink, so in a more hidden locationThe system is installed at the point of entry of the water in your house
SizeLarge systems, but will be hidden under the sinkLarge systems as need to have the capacity to filter all the house water
CapacityBecause they are large systems designed to filter the water of  just one point, the sink, they will last longer and the filter cartridge needs to be replaced less oftenThese systems are designed to filter all the water of your home so they will have a large capacity and the filters will last long, typically more than 6 months
InstallationRelatively easy and straightforward, but you may have to drill a hole in your sink to install an additional faucetMore complex installation process
CostAffordableExpensive, when compared with under sink water filters
Reverse Osmosis SystemThere are RO under sink water filter systemsTypically RO is not used for whole house water filters as they produce waste water, and that wouldn’t be efficient to filter all the water in your home
POE or POUPoint-of-UsePoint-of-Entry

Conventional Under Sink Water Filter System vs Reverse Osmosis System

You may have decided to for an under sink water filter, but you are still wondering if you should go for a conventional system or a Reverse Osmosis system.

Both systems are good options, but in our view, 2 major factors differentiate them and might help you to decide.

A Reverse Osmosis system removes a diverse amount of contaminants, as the RO process is a powerful filtration method that combines different filters and filtration stages to provide pure water.

On the other hand, a Reverse Osmosis system generates waste water, so for each gallon of filtered water is wastes between 1 gallon (efficient system) to 3 gallons (typical RO systems), which is a problem that you won’t have with a conventional under sink water filtration system.

Under Sink Water Filter Benefits

Removes Contaminants & Impurities from Your Water

The main benefit of an under sink water filter, like any water filter, it’s their ability to remove harmful contaminants and impurities from your water, improving its quality.

An under-sink water filter can remove impurities, sediments, heavy metals, chlorine, arsenic, bacteria, viruses, nitrates, etc., to ensure that you and your family have access to clean and fresh water to drink.

Improve Water Taste & Odor

Under sink water filters can improve the taste and odor of your water, because some of the removed contaminants are not only bad for your health, they are also responsible for the bad taste and odor.

An activated carbon filter is especially efficient at removing bad taste from the water, and most of the under sink water filters will have one of these filters.

Countertop Space Saving

One of the good things about under sink water filters is that they are hidden under the counter, so there is no need to take important countertop real estate like a countertop water filter does.

Even if it takes more space and is generally less aesthetically pleasing than a countertop water filter, that is not a problem because it stays in a closed cabinet.

Environment-friendly

By using an under sink water filter system you will heavily reduce your bottled water consumption, which is really beneficial for the environment.

With this choice, you will reduce the amount of plastic waste in our oceans.

Cost

There are some costs associated with buying an under sink water filter, not only the initial cost but also the recurring costs associated with replacing the filters periodically.

But the cost of this type of water filter is not that high, and they are less expensive than other types of water filters.

Their durability and high efficiency in removing contaminants make this type of water filter a really good cost-effective option.

And if currently you spend money buying bottled water, buying an under sink water filter is a no-brainer option – you will save lots of money in the long run.

Easy to Maintain

Under sink water filter systems need some maintenance, as you need to change the filters with a pre-determined frequency.

But this is a simple task that you can do in a few minutes, as most of the systems are designed to make this activity user-friendly.

And the capacity & lifespan of most under sink water filters are longer than other water filter types, like countertop or faucet filters, so you don’t need to replace the filters quite as often.

Under Sink Water Filter Disadvantages

Single Point of Use (POU)

While a whole house water filter can filter the water of your entire house, an under sink water filter can only filter the water that comes through one faucet, so it works only on a single point.

If you need more points in your house with filtered water, you will need to buy additional filters, which is not ideal if that is your situation.

Separate Faucet

For the conventional under sink water filters, there is a need to install a separate faucet that delivers the filtered water.

This faucet comes with the device but implies that you will have more effort installing it.

Installation

While the installation of an under sink water filter is not overly complicated and can be done by people with basic manual skills, it requires more effort and manual labor than the installation of other types of water filters, like countertop or faucet water filters.

And if you choose a conventional under sink water filter, you might need to drill through your countertop to install a separate faucet, if your countertop isn’t already prepared with a pre-drilled hole, making the installation process a bit more complex.

Is an Under-Sink Water Filter Right For Me?

There are different factors to consider if an under sink water filter is the right choice for your situation.

If your water is contaminated and you want access to clean and pure water, a water filter is a good solution.

If you and your family need a significant amount of clean water to drink and cook on-demand, without having to wait some time for the water to be filtered, an under sink water filter is a good option.

Another good reason to opt for an under sink water filter is If you have enough space under the kitchen sink and you don’t want to use your countertop space with a water filter.

If you are spending lots of money on bottled water, an under sink water filter will give you better quality water at a fraction of the cost of bottled water.

On the other hand, if you don’t need much water, you don’t need to remove many contaminants because your water is relatively clean, you have a tight budget, and have time to wait for filtered water, a water filter pitcher might be a better choice for you.

And if you need to get filtered water not just in one location, the kitchen sink, but on the entire house, a whole house water filter might be a better choice.

One of the reasons to not opt for an under sink filter is if you are renting and the countertop doesn’t have a pre-drilled hole for the additional faucet, maybe it is not the solution for you because you would have to drill the countertop. In this case, a countertop water filter would be a better choice for you.

How to Install an Undersink Water Filter

Each under-sink model might have its specific installation process, so you should always follow the manufacturer’s instructions and video to understand the proper installation process.

Below we will give you an idea of the usual steps involved in the installation of a conventional under sink water filter.

Step #1: Turn off and Disconnect the Cold Water

Before starting the installation, turn the shut-off valve to turn off the cold water, and disconnect the cold water line.

You can use a towel to clean some water that was on the pipes.

Step #2: Select the Water Filter Location

Select the location where you want to place the under sink water filter, and put the filter in place. Take into consideration that you need to leave some space to be able to change the filters from time to time.

Step #3: Connect the FIlter to the Cold Water Supply

Now you need to connect the cold water line to the under sink water filter system.

Step #4: Install the Faucet

If you need to install a faucet, this is the time to do it. If your sink does not have a pre-drilled hole, you will need to drill a hole on it.

This is the most complicated step so make sure you take the necessary precautions. Use the right tools and wear safety glasses.

After drilling the hole in your sink, place the faucet in it and align it in the right direction, and connect the tubes at the bottom of it to the water filter.

Step #5: Mount the Water Filter

You can now secure the under sink water filter to the side you selected. As mentioned before, just make sure that you have room to change the filters in the future.

Step #6: Turn the Water Back On

Turn the water on and check if there are any leaks or defects in the installed system.

Step #7: Test the System

Finally, you need to test it to check that it’s working properly. Turn on the faucet to let the water run for a few minutes to flush it out.

If you have to install a simple under sink water filter system, the installation process is even easier as you don’t have to worry about the additional faucet.

Just connect the filter directly to the cold line, integrating the under sink water filter system into the path of the cold water supply.

If you selected a Reverse Osmosis under sink water system, you can find how to install a Reverse Osmosis System in 10 steps in our RO review guide.

Under Sink Water Filter Maintenance

The under sink water filter maintenance is simple, and there are only two main topics to consider: when and how to change the filter cartridges.

When to Change the Under Sink Water Filter Cartridge?

There is no direct answer to this question because it depends on the model you choose, and the replacement frequency can vary a lot.

In some models, you may need to change the filter every 6 months, others work properly for 2 to 3 years until you need to change the filter.

Of course, if you are a heavy user or if your water is heavily contaminated, you may need to change the filter more frequently than indicated.

How to Change the Under Sink Water Filter Cartridge?

The process to change the filter cartridge of an under sink water filter is usually straightforward.

You just need to turn off the water supply, open the case where the filter is, remove the old filter, replace it with the new one, and close the case.

Then just let the water run for a few minutes to check if everything is working properly.

FAQ About Under Sink Water Filters

Here are some answers to frequently asked questions about undersink water filters.

How much does an under sink water filter cost?

There are different types of under sink water filters, which will have an impact on the cost. So you can find under sink water filters from $100 up to $500.

Take also into account a recurrent cost associated with the replacement of filters.

And if you have to hire a plumber to install the under sink water filter, add an additional $100 to $200 to your budget.

Should I get an under sink water filter system or an RO system?

In this case, you can have the best of both worlds as some under sink water filters are Reverse Osmosis systems.

You can choose a conventional under sink water filter or a Reverse Osmosis under sink water filter, and the big difference is that typically the RO system can remove more contaminants as it goes through several filtration stages and uses RO process to clean the water.

Can I install an undersink water filter myself, and change the filters?

Today the under sink water filters are relatively easy to install, and the manufacturers provide easy step-by-step instructions and detailed videos to show you how to do it by yourself.

So, if you have some manual ability, you should be able to do it by yourself without any problem.

Changing the filter’s cartridge is an easy activity that for sure you can do by yourself.

Is under sink water filter water better than bottled water?

With both options, you will have clean water, but the big difference is that if you drink filtered water instead of bottled water, you will reduce the amount of plastic waste generated by the bottles, reducing your environmental footprint.

Another benefit is the amount of money you will save because the initial investment on an under sink water filter will be quickly paid by the amount of money saved for not buying bottled water.

Our Verdict

After reading our comprehensive guide and detailed under sink water filter reviews, you are in a good position to select the best model for your home.

Any of the options we presented would be a good choice to deliver filtered water for you and your family to drink and cook.

For us, the best overall choice is the Waterdrop G3 Reverse Osmosis Under Sink Water Filter System, but all the under sink water filters we listed are great options, so you can’t go wrong with any of these options!