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10 Best Under Sink Water Filters of 2023: Consumer Report

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Are you still surveying for the best under sink water filter for your home?

Most areas do not have access to clean water for safe consumption, including the United States.

The water you use daily probably contains a certain amount of heavy metals like lead and iron, VOCs, cysts, herbicides, and even microorganisms like bacteria and viruses.

These harmful contaminants will cause health problems for your family in both the short term and long term. More seriously, some of these health problems are fatal.

If you live in these areas, the best under sink water filter is a mandatory device to keep your family and yourself away from illness due to the consumption of contaminated water.

Sometimes, finding a high-performance yet affordable under-sink water filtration system is challenging.

I’ve done all the hard work for you with my years of expertise and experience.

Trust me, what I am going to show you is the real deal about under sink water filtration system that fits your needs.

I’m not some random bloggers that simply grab a few water filters from online marketplaces and call it a day (I have seen many from just a few simple Google searches).

Even with my years of expertise in the water treatment industry, I still spent a few days researching, survey, analyze, compare (in-depth), and filter to come out with this best under-sink water filtration system list that I’m satisfied with.

Table of Content show

Top 10 Best Under Sink Water Filter of 2023 (At a Glance)

Before we moving to the buying guide and detailed reviews, let’s have a look at the top 10 list of the carefully picked under sink water filtration system first:

  1. Waterdrop WD-G3P600-W Tankless ROBest Under Sink Tankless RO (Overall)
  2. APEC Top Tier Supreme RO-PH90Best Under Sink RO Filter
  3. APEC WFS-1000 3-Stage Under SinkBest Value (Non-RO)
  4. Home Master TMAFC-ERP ArtesianBest Water Efficiency (RO)
  5. iSpring CU-A4 Compact SystemBest Ultrafiltration (UF)
  6. iSpring RCC7AK-UV Deluxe Under SinkBest Under Sink RO with UV
  7. Express Water RODI10D Deionization ROBest Water Purity
  8. Express Water ROALK5D Alkaline ROBest Under Sink Filter for Alkalinity
  9. Woder 10K-Gen3 Water FilterBest Long-lasting Under Sink Water Filter
  10. Culligan US-EZ-4 EZ-Change Water FilterBest Budget Under Sink Filter

What is an Under Sink Water Filter?

An under-sink water filter is a water treatment device that is installed underneath the kitchen sink to filter water going to the faucet to provide you with clean and safe water for consumption and cooking.

Under sink water filters are commonly used in homes and offices to supply clean drinking water.

Why Use an Under Sink Water Filtration System

Because the water you are getting contains a lot of harmful contaminants such as sediments, chlorine, heavy metals, fluoride, lead, VOCs, bacteria, and viruses.

The best candidate to remove these contaminants is the under sink water filter because they are generally larger and consist of multiple stages of different filters, so they tend to offer the highest filtration power in removing over 99.9% of harmful contaminants in water.

Under sink water filtration systems also come with a variety of choices to deal with all kinds of different contaminants in water, if you want to remove Chlorine, there are activated carbon filters, if you want to remove microorganisms, there are UV filters, and if you want to remove total dissolved solids, there are RO filters.

To protect you and your family from contaminated water, you will need the best under-sink water filter for your home.

Under-sink is among the most popular types of water filtration system sought by families, especially those with more family members.

The reasons why many people prefer an under counter water filter are:

  • Strong filtration performance
  • Under counter placement
  • Last longer (higher capacity)
  • More choices of filtration system
  • Fast water filtration rate

Strong Filtration Performance

One of the main reasons why people are using an under-sink water filter at home is because of its strong filtration performance in getting rid of harmful contaminants in tap water.

Its high filtration power is achieved by the flexibility in utilizing multiple filters in a stages filtration process to remove a wider range of water contaminants.

Because the under sink system can fit in multiple stages of filters, allow it to have more features like UV disinfection, remineralization, and taste improvement.

If you want the best water filtration for your home, you’ll have to go for an under sink filtration system (most of the time).

Under Counter Placement

When comes to home and kitchen-related things, space and appearance are two important elements to consider.

The advantage of using an under sink system is it will not occupy any sink top space like a countertop system, especially if your kitchen is not big.

Also, some families have certain theme colors or designs for their kitchens, so having an under-counter water filter hiding in a covered space will not affect the theme aesthetically.

Last Longer (Higher Capacity)

Another advantage of under sink water filtration system is its higher filtration capacity, allowing it to last longer and reduce your maintenance frequency for filter replacements.

More Choices of Filtration System

There are more choices of filtration system for the under-sink setup, such as reverse osmosis, ion-exchange, ultraviolet (UV), activated carbon, sediment, ultrafiltration (UF), and ionization.

If you prefer to use a filtration system other than sediment and activated carbon, under sink water filter is your go-to pick.

Fast Water Filtration Rate

Except for the Reverse Osmosis system, all the under sink water filtration system comes with high water filtration rate, saving your time in filling up your water bottle or cup.

Top 10 Best Under Sink Water Filter [Reviews]

Here are the reviews of each under sink water filter and the reasons why they were picked and included in this top 10 list.

1. Waterdrop WD-G3P600-W Tankless RO [Review] – Best Tankless Reverse Osmosis Under Sink Water Filter

Waterdrop WD-G3P600-W Tankless RO


  • Effectively remove 99% of major contaminants
  • Tankless design
  • An intelligent water filtration system
  • Quick and easy installation
  • Quick 1-turn filter change
  • Space efficient
  • Fast water filtration rate of 600 GDP with an internal pump
  • Efficient wastewater to clean water ratio of 2:1
  • Beautiful design
  • Smart faucet
  • More

The Waterdrop undersink water filter WD-G3P600-W is an innovative high-performance tankless Reverse Osmosis water filtration system that’s capable to remove most contaminants in tap water with filtration size down to 0.0001um.

With the combination of sediment filter, activated carbon, and reverse osmosis technology, this water filtration system can effectively remove a wide range of contaminants such as chlorine taste and odor, heavy metals (eg: lead, mercury, copper), carcinogens (eg: cadmium, chromium), microorganisms (eg: cysts, bacteria), Inorganic contaminants (eg: arsenic, fluoride), organic contaminants (benzene, lindane), total dissolved solids (TDS), turbidity, and more.

Here’s the breakdown of the Waterdrop undersink filter:

Stage 1 – CF Filter (PP + Activated Carbon): Removes rust, sand, silt, chlorine taste and odor, volatile organic compounds (VOCs), and more particulates.

Stage 2 – RO Filter (RO membrane): Removes contaminants like heavy metals, microorganisms, and inorganic compounds, and reduce total dissolved solids (TDS) and scale.

Stage 3 – CB Filter (Activated Carbon): Improve water taste.

Moreover, the tankless design takes up less space and protects the system from secondary pollution like bacteria growth.

Also, with the help of an internal pump, this Waterdrop tankless RO system is producing pure water at a 600 GPD rate, which is about 8 times of most Reverse Osmosis systems in the market, with no more waiting time for filling up your water bottle or cup.

Water efficiency is another factor to consider in this tankless Reverse Osmosis system. With a wastewater to clean water ratio of 2:1, it can save a lot of water and reduce your water bill.

Note: You need to flush the whole system for at least 30 minutes or 8.5 gallons of water after installation. Alternatively, you may flush and wait until the blue light on the faucet stop flashing.

Want a powerful Reverse Osmosis system but without the cons like slow filtration rate, water tank, a large amount of wastewater, complex installation, and bulky in size?

The answer is Waterdrop WD-G3P600-W Tankless Reverse Osmosis system.

It’s nice-looking, compact in size, strong filtration performance, no water tank, fast water filtration rate, easy installation, quick filter replacement, less wastewater, smart faucet, smart leakage detector, and embedded with sensors to remind filter life, water quality, and TDS value in real-time.

Also, the Waterdrop tankless RO system WD-G3P600-W comes with a leakage protector that monitors leakage in real-time and will cut off water and power supply automatically in case leaking happens to protect your property and electrical appliances.

I also like the smart faucet that indicates the filter status, so that I don’t have to open up the bottom cabinet and check every time.

Basically, I think the only con is the price.

However, in the long run, the greater water efficiency (2:1) does compensate for the extra cost of the system with the lower monthly water bills.

If you can afford it, get it and you won’t regret it, it’s really good.


  • Strong water filtration power
  • Fast water filtration rate of 600 GPD with an internal pump
  • 2:1 clean water to wastewater ratio
  • Compact and space-efficient
  • Tankless
  • Quick and easy installation
  • Fast filter replacement
  • Good quality materials
  • With leakage detector
  • Comes with a smart and lead-free faucet
  • 1-year warranty


  • Expensive
  • Require electricity

Waterdrop G3P600 Discount Code: Apply the code "BRIZFEEL5" to enjoy an additional 5% OFF!

2. APEC Top Tier Supreme RO-PH90 RO Water Filter [Review] – Best Under Sink RO Filter



  • Effectively removes 99% of contaminants in tap water
  • Strong filtration performance with 6 water filtration layers
  • High flow rate at 90 GPD
  • Produce high-purity mineralized drinking water with calcite remineralization.
  • Improved water taste by raising the pH level and neutralizing acidity in the water
  • More

The APEC Top Tier Supreme RO-PH90 is a powerful Reverse Osmosis system with a remineralization feature that provides pure and tasty water to your family.

It’s capable to remove 99% of contaminants including chlorine, lead, bacteria, fluoride, viruses, heavy metals, arsenic, and more.

The system comes with a 100% lead-free and metal premium designer faucet and FDA Certified JG food grade tubing for safe and contamination-free drinking water.

Besides, it includes a 100% US-made high-purity calcium carbonate mineralizing water filter to enhance pH in the water, which is great for those who are looking for alkaline water.

In terms of security, the APEC Top Tier Supreme RO-PH90 water filter is WQA certified and comes with 2 years manufacturer warranty and lifetime support to provide you with peace of mind.

In terms of performance and overall functionality, APEC Top Tier Supreme RO-PH90 is the best Reverse Osmosis system that you can get for your family.

It has a high filtration power, fast water production rate, high tank capacity, remineralization, and is made by a US-based reputable brand.

One of the concerns people avoided Reverse Osmosis is because it removes beneficial minerals in the water, but with the remineralization feature, you can get the best of both worlds – clean water with only healthy minerals.

To me, this Reverse Osmosis filter system is quite easy to install as there’s nothing complicated to put the system up, mostly just connect the tubings.

All these benefits simply make it the top choice for kitchen sink water filter.

Also, the instruction given is very clear and even come with pictures, I just follow it closely and get the job done in under an hour.

Oh ya, remember to flush the system first before you start drinking the water. To do that, after you’ve installed the system, open your water supply and fill up the tank until full (for me it took about 2.5 hours).

Once the tank is full, drain it until empty and repeat the same process one more time before you start drinking the water.


  • Strong filtration power
  • High water filtration rate
  • Good material quality
  • Large water storage capacity.
  • Simple Installation
  • Parts are industry standard


  • Price on the high side
  • No leak detector

3. APEC WFS-1000 Under Sink Water Filter [Review] – Best Value (Non-RO)

APEC WFS-1000 3 Stage Under-Sink Water Filter System image


  • Great water filtration performance
  • Fast water filtration rate of 1 gallon per minute (GPM)
  • Utilize 3 filtration layers to remove major contaminants like chlorine taste and odor, rust, sand, solids, VOCs, and more
  • Made in the USA for quality assurance
  • Comes with FDA-certified JG food grade tubing and a lead-free chrome faucet for water safety.
  • All the 3 filter cartridges can last up to 12 months.
  • Backed by a one-year satisfaction guarantee and lifetime support from APEC.
  • More

The APEC WFS-1000 3-stages under sink water filtration system is a fast water filter (or called hi-flow water filter) that delivers clean drinking water to your faucet quickly to shorten the waiting time to fill up your cup or bottle.

Here’s the breakdown of the APEC 3-stages under sink water filtration system:

1st stage – Sediment filter (10-inch PP): Remove large particles, rust, dust, sand, and more.

2nd & 3rd stage – 2x Extruded Carbon Block: Greatly remove chlorine taste and odor, VOCs, chemicals, and impurities from the tap water while keeping the beneficial minerals and water alkalinity.

All three high-capacity filter cartridges can last up to 12 months. The longer filter life also means fewer replacements and lower maintenance costs for using this under sink filtration system.

Looking for the best non-RO water filtration system (under the sink) that is affordable and provides great water filtration?

This is the one.

The APEC WFS-1000 3-stages under sink water filtration system offers a great water filtration for a home in getting rid of common contaminants, impurities, and chemicals while keeping the beneficial minerals in your tap water.

Also, due to the direct flow-through filtration system, there is no wastewater produced in the filtration process while providing a constant supply of clean and tasty filtered water.

For busy folks, this fast water filter will prevent you from getting angry and frustrated in filling up your bottle and cup.

Not only that, If you prefer not to have the same filter in stages 2 and 3, you can also replace the stage 3 filter with one of the six alternative filters based on your water condition, which are FI-CHLORAMINE, FI-FLUORIDE, FI-CERAMI, FI-PHPLUS, FI-NITRATE, and FI-ARSENIC.

If your tap water quality is soft, then this is the best under counter water filter for you.


  • Strong water filtration capability without producing wastewater
  • High water filtration rate at 1 GPM
  • Retain beneficial minerals in the water
  • Interchangeable filter cartridges for different removal purposes
  • Affordable price
  • No water tank
  • Longer filter life up to 12 months
  • Simple and fast installation
  • Great water taste
  • Comes with stainless steel faucet


  • Cannot reduce TDS value in tap water
  • Weaker filtration power compared to Reverse Osmosis
  • No filter replacement indicator
  • Moderate quality of fittings

4. Home Master TMAFC-ERP Artesian with Permeate Pump [Review] – Best Water Efficiency (RO)

Home Master Artesian Full Contact with Permeate Pump image


  • Consists of 7 stages of water filtration and enhancement which is capable to remove 99% of contaminants like chemicals, sediments, heavy metals, and inorganic compounds
  • Come with a built-in non-electric permeate pump (made in the USA) to reduces water waste up to 80% and increases water production by up to 50%
  • Patented Full Contact technology adds calcium and magnesium minerals twice during the purification process
  • Long-lasting and easy-to-change filters
  • Replace filters only once a year
  • More

The Home Master Artesian Full Contact with Permeate Pump uses 7 stages of water filtration and enhancement to remove up to 99% of chlorine, chloramines, heavy metals, pharmaceuticals, dissolved solids, and other contaminants. 

Its innovative design eliminates the most common problems like canister filter housing leaks, high water waste, slow flow rate, service challenges, and slightly acidic water.

Besides, the Reverse Osmosis systems use catalytic carbon filtration media in the carbon pre-filters to treat the chloramine, which normal carbon filters are unable to effectively remove.

Also, some Reverse Osmosis water filtration systems produce highly pure but slightly acidic water, and when the acidic water sits in the storage tank, the acidic water dissolves some of the rubber bladders and causes storage tank degradation which affects the taste of the water.

In contrast, the Home Master Artesian Full Contact with Permeate Pump prevents storage tank degradation from occurring with its patented ‘Full Contact’ remineralization system. This system balances the water’s pH level by adding a small amount of calcium and minerals (30-60 mg/L combined) through a natural process when the water travels to the storage tank and when the water travels to the faucet.

Compared to other Reverse Osmosis systems, the Home Master TMAFC-ERP Artesian Full Contact uses a modular “all-in-one” design where the filter is incorporated into the filter housing to avoid the possibility of the microorganisms, sediments, and biofilm accumulate in the filter housing and cause leaking.

Last but not least, the Home Master TMAFC-ERP Artesian Full Contact is made in the USA and backed by a 5 years limited warranty.

The unique point about this RO water filter system is it incorporated a permeate pump.

The permeate pump makes use of the brine’s hydropower to overcome the backpressure from the tank and allow the Reverse Osmosis water filtration system to take advantage of the pressure it has to fill up the water tank faster, hence reduce the amount of brine by up to 80% and increase water production by up to 50%, which improve the system efficiency significantly.

It’s the best under sink Reverse Osmosis system for water efficiency.

Also, it provides slightly cleaner water by eliminating TDS creep.

On top of that, the Home Master TMAFC-ERP Artesian Full Contact uses larger fittings, tubing, and high-flow components to further increase the water’s flow rate to the faucet. So it’s great for those who want to fill up their glasses fast.

From my research, I found that the majority of buyers have positive reviews in using this Reverse Osmosis system for months to years, which you can rest assured for the product quality in the long run.


  • Strong filtration performance
  • Better water efficiency (less wastewater)
  • Fast clean water production rate
  • With permeate pump that doesn’t require electricity
  • The installation and annual maintenance are quick and simple
  • Reasonable price for the features and quality
  • Comes with integrated filters and filter housing that you can simply replace every year easily


  • The design of the whole system is just normal and looks a bit cheap
  • The instruction manual is not simple enough for beginners with no basic skills. You may have to follow the online instructional videos.
  • Due to the addition of a permeate pump, more tubes are crossing around and make the whole system look messy
  • The quality of the fitting is moderate

Upgrade Recommendation:

Want to destroy harmful microorganisms in your tap or well water?

Just upgrade to the Home Master TMHP HydroPerfection Reverse Osmosis System, it has all the benefits of Home Master TMAFC-ERP plus a UV filter and an Iron removal prefilter.

5. iSpring CU-A4 Ultrafiltration Water System – Best Ultrafiltration (UF)

iSpring CU-A4 Ultrafiltration Water System


  • Effectively removes up to 99% of harmful contaminants like chlorine, lead, bacteria, arsenic, giardia, volatile organic compounds (VOCs), and more
  • Retain essential minerals in the water
  • Compact size with no water tank
  • No wastewater
  • Simple installation and maintenance
  • CU-A4 Easy-Twist Cartridges make filter replacement quick and easy
  • All components comply with ANSI/NSF standards and FDA for quality assurance
  • More

The iSpring CU-A4 is a 4-stage compact water filtration system with Ultrafiltration (UF) and KDF/GAC technology to remove a wide range of harmful pollutants in tap water while keeping the essential minerals for great taste and alkaline balance.

Here’s the breakdown of the 4 progressive filtration stages:

Stage 1 – Sediment Filter (5-micron Polypropylene): Get rid of larger particles like sand, rust, silt, dirt, and solids.

Stage 2 – UF membrane (0.1-micron hollow fiber): Removes harmful contaminants like bacteria, cysts, giardia, pharmaceuticals, algae, and protozoa.

Stage 3 – Kinetic Degradation Fluxion (KDF) + GAC: Removes water pollutants such as heavy metals (eg: lead, chromium), arsenic, hydrogen sulfide, germicides, chloramine, pesticides, and bacteria. 

Stage 4 – Activated Carbon Filter (Coconut Shell): Removes residual chlorine taste and odor.

The water filtration system is tested against ANSI/NSF standards 42 (chlorine taste and odor, particulates), 53 (lead, asbestos, VOCs), 401 (pharmaceuticals, pesticides, germicides), and P472 (PFOS, PFOA) for water quality and comply strictly with FDA standards.

Need a high-performance water filtration system but don’t want the slow filtration rate, space-consuming, and high cost from a Reverse Osmosis system?

The Ultrafiltration (UF) technology is your best choice.

It has a 0.1-micron filtration accuracy, enough to get rid of a large range of harmful contaminants while having a 0.56 GPM filtration rate and retaining essential minerals in the water.

Besides, the iSpring CU-A4 water filtration system also comes with a Kinetic Degradation Fluxion (KDF) Media, which gives it the edges in fighting against heavy metals and microorganisms.

Bear in mind that the UF membrane is not good in reducing total dissolved solids (TDS) in water, so if your tap water is hard, then you should go for a Reverse Osmosis system; if the tap water is soft, then Ultrafiltration (UF) is more suitable for you.


  • Great filtration performance
  • Fast water filtration rate
  • Compact and analyze
  • Retain healthy minerals in the water
  • No wastewater
  • Great filtered water taste
  • Easy to install
  • Quick filter change


  • Not effective in reducing TDS value
  • Can’t remove contaminants smaller than 0.1 micron

6. iSpring RCC7AK-UV Reverse Osmosis Water Filter [Review] – Best RO with UV

iSpring RCC7AK-UV Reverse Osmosis Water Filter image


  • The water filter system contains 7 different stages of water filtration and UV sterilization to remove up to 99.99% of contaminants, including arsenic, mercury, fluoride, chlorine, hormones, asbestos, bacteria, viruses, giardia, microorganisms, and more
  • The existence of the UV sterilization stage makes RCC7AK-UV the perfect solution to purifying water sources containing excessive microorganisms (eg: water from wells, lakes, and streams).
  • The Alkaline Remineralization (AK) filter restores useful minerals and produces alkaline-balance water
  • Good water filtration rate of 75 GPD
  • Transparent 1st stage housing makes filter inspection easy
  • More

The iSpring RCC7AK-UV is a 7-stage multi-layered Reverse Osmosis system that is tested and certified by WQA to remove up to 99.99% of harmful contaminants that commonly appear in the city including chlorine, arsenic, fluoride, lead, bacteria, mercury, viruses, giardia, asbestos, hormones, sodium, and more.

All components including filters, tank, tubing, and other water-contacting parts are manufactured to comply strictly with NSF/ANSI standard (58 for Reverse Osmosis) and FDA (CFR-Parts 174).

The Alkaline Remineralization stage restores the right proportion of beneficial minerals and natural taste, and the high-performance UV stage provides an extra level of protection against viruses and microorganism contamination.

The iSpring Reverse Osmosis system also went through rigorous testing for air leaks, pressure, and cycle resistance to maintain the quality and high-performance standard.

The filtration system consists of 7 filtering stages, each one is designed to progressively remove contaminants and improve the water quality:

1st stage (pre-filter) – Sediment filter (PP): Removes larger particles and contaminants to protect the water filter system from clogging.

2nd & 3rd stage (pre-filters) – KDF/GAC & Carbon block (CTO): To protect the RO membrane from chemicals like chlorine and chloramines.

4th stage (core filter) – RO membrane: Removes contaminants down to 0.0001 microns, which is too small until only water molecules can squeeze through.

5th stage (post-filter) – GAC filter: Provides final polishing by absorbing undesirable taste, odor, and color before the purified water is delivered to the next stage.

6th stage (post-filter) – The 11-watt UV lamp: Provides an additional level of protection through Ultraviolet Sterilization against a wide variety of viruses and microorganisms that might pass through the first 5 stages.

7th stage (post-filter) –  Alkaline Remineralization filter: Restores healthy minerals and a natural alkaline balance to produce a more natural taste.

The combination of both GAC and CTO filters in the 2nd and 3rd stages provides greater protection against harmful chemicals like chlorine than CTO alone.

The iSpring RCC7AK-UV uses an 11 watt UV lamp shielded in a stainless steel housing with a flow sensor switch to control the UV lamp on and off automatically with the water flow for power saving and lengthening the lifespan of the UV lamp.

The UV sterilization stage kills the small percentage of viruses, bacteria, and other microorganisms that could potentially remain in the water after the Reverse Osmosis process.

The Alkaline Remineralization (AK) stage is designed to restore the natural minerals and alkaline balance of the water. The red mineral stone portion of the AK filter adds back healthy minerals including not just calcium, magnesium, and more. The calcite portion of the filter neutralizes the pH of the RO water and makes the water tastes better with the presence of minerals.

The system also includes a lead-free, solid brass faucet with a brushed nickel finish for you to mount on the counter to enjoy your clean and healthy drinking water.

The iSpring RCC7AK-UV is one of the best kitchen sink water filter for all families.

For your peace of mind, the entire system is backed by a 1-year money-back guarantee, a 1-year manufacturer warranty, and iSpring’s lifetime technical support.

From my findings, the iSpring RCC7AK-UV is the best under-sink Reverse Osmosis system with a UV feature.

Personally, I think UV is unnecessary for treated water unless the water source is untreated (eg: lake, river) and the condition is really bad.

But if you are looking for a complete solution of water purification, a Reverse Osmosis filtration system with UV sterilization is by far the most complete method available.

Because of its super filtration performance, it’s also the best under sink Reverse Osmosis system for well water.

The whole system is designed for do-it-yourself installation and fits nicely under a standard kitchen sink.

Also, the installation is straightforward and guided by clear written instructions and instructional videos.


  • Strong water filtration performance
  • Highly effective against major contaminants including microorganisms
  • The installation is considered simple for someone with basic skills
  • Produce clean and alkaline-balance drinking water
  • The customer service of iSpring is quick in handling the customer’s problems and issues


  • Required power socket and electricity to turn on the UV light
  • The UV lamp could be unnecessary for a treated water source
  • The system set up time could be time-consuming due to many connections and the instruction is not simple enough

7. Express Water RODI10D Deionization Reverse Osmosis Water Filter – Best Water Purity

Express Water RODI10D Deionization Reverse Osmosis Water Filter


  • Effectively removes 99% of water pollutants like chlorine, fluoride, arsenic, nitrate, lead, bacteria, calcium, VOCs, and more
  • Fast water filtration rate of 100 GPD
  • Quick and simple installation
  • Comes with an emergency leak stop detector
  • Deionized water for aquarium’s setup
  • More

The Express Water RODI10D is a 6-stage Reverse Osmosis water filtration system with deionization technology to hugely reduce total dissolved solids (TDS) and harmful contaminants in tap water.

Here’s the breakdown of the 6 stages of filtration layers:

Stage 1 – Sediment Filter: Removes rust, sand, dust, dirt, and larger particles.

Stage 2 & 3 – Carbon filters: To get rid of pollutants like chlorine taste and odor, volatile organic compounds (VOCs), and more.

Stage 4 – RO membrane: Removes most water contaminants like bacteria, arsenic, lead, fluoride, viruses, total dissolved solids (TDS), and more.

Stage 5 – Deionization filter: Removes dissolved contaminants and minerals in the water.

Stage 6 – Activated carbon filter: Removes residual taste and odor.

Moreover, the system also has a high filtration rate of 100 GDP and a leak stop valve to protect your property from water leakage.

If you want the purest water with the lowest possible TDS value, you can’t run away from this water filtration system, a combination of Reverse Osmosis technology and Deionization (Ion-exchange technology) to produce the maximum purity water.

If your tap water is very hard, I highly recommend you use this water filter to soften the water hardness level. It is one of the best under sink water filtration system for home.

Also, you can use the high purity deionized water for many purposes like car reservoir, aquarium, cooking, brewing coffee, planting, cleaning, making ice, and more.


  • Strong filtration performance
  • Hugely reduce TDS value
  • Produce deionized water with maximum purity
  • Fast water filtration rate
  • Simple and quick installation
  • The filtered water is great for aquarium use
  • With leak detector


  • Plain water taste
  • Produce wastewater (brine)

8. Express Water ROALK5D Alkaline RO Water Filtration System [Review] – Best Alkalinity

Express Water Alkaline Reverse Osmosis Water Filtration System image


  • Removes 99% of Bacteria, Viruses, Heavy Metal, Chlorine, Radium, Lead, Arsenic, Fluoride, and more harmful contaminants
  • Up to 20% more oxygen than regular water
  • The Active Mineral Technology adds Calcium, Magnesium, Potassium and other minerals into your water
  • Quick and simple installation
  • More


The Express Water ROALK5D consists of 5 stages of water filtration and 5 stages of mineralization, giving you clean drinking water with useful minerals like potassium, calcium, magnesium, and more.

Here’s the breakdown of the 10-stages express water filter system:

1st stage – Sediment filter: To filters out rust, dirt, sand, dust, etc.

2nd & 3rd stages – Carbon block & Granular carbon: To focus on getting rid of chlorine, volatile organic chemicals (VOCs), and odor.

4th stage (core) – RO Membrane: Focuses on the most difficult contaminants like arsenic, lead, chromium, TDS, radium and more.

5th-9th stages – 5x Mineralizing filters: To adds 5 stages of mineralization, antioxidants, and oxygen into your clean water. The minerals are ionically activated so the water picks up more mineral content as it passes through the five stages of mineral rocks, the same way the healthiest natural springs on Earth add minerals.

10th stage – Post Activated Carbon Filter: Removes any possible taste or odor.

Filtered water is also a great source of antioxidants with up to 20% more oxygen.

For the accessories part, the Express Water Filter System ROALK5D comes with a fast flow rate faucet with 0.8 GPM and a 4 gallons (3.2 gallons net water capacity) water storage tank and tank stand.

The Express water filter system comes partially pre-assembled, so it just took me about 35 minutes to identify all the parts and put it up, which saved my pocket on hiring a plumber.

If you are concerned about the size, no worry, it’s a compact system made to fit under a sink in a cabinet, either sit upright or on its side (great for small cabinets).

Out of curiosity, I’ve measured the filtered water with my pH meter and got a reading of 10.2 pH (comparable to some of the expensive alkalizing machines in the market which cost you thousands of dollars), which is great for people who preferred alkaline water.

The system uses separate cartridges to add minerals into the water and raise water pH level naturally (same as stream water), which is far better than ionized water.

I’d definitely recommend Express Water Filter ROALK5D to those who prefer to drink alkaline water as it’s the best under-sink Reverse Osmosis system for alkalinity.


  • Great alkaline water taste
  • Strong filtration capability
  • Fast and simple installation with the Quick Connect tubing system
  • Compatible with 3/8″ and 1/2″ under sink connections
  • High water storage capacity
  • Certified by an independent laboratory to NSF standard 58 for water safety and quality
  • Reasonable price


  • Slower water filtration rate
  • For those who prefer lower alkalinity, then the system output water pH is too high for you

9. Woder 10K-Gen3 Under Sink Water Filter [Review] – Best Long-Lasting

Woder-10K-Gen3-Ultra-High-Capacity-Direct-Connect-Water-Filtration-System image


  • Remove up to 99.9% lead, chlorine, chromium 6, mercury, carcinogens, VOCs, heavy metals, turbidity, odor and bad taste, and more contaminants from tap water
  • Super-high capacity filter which lasts up to 10,000 gallons of filtered water or 3 years
  • A high water flow rate of 2 GPM
  • Tested by independent laboratories to ANSI standards
  • More

The Woder 10K-Gen3 Water Filter is a high capacity direct-connect under sink filter that can effectively remove chlorine, bad taste and odor, lead, and other contaminants for a long period.

The Woder filter use microparticles to contain more filtering ingredients so that it can stay effective for a longer time compared to other filters.

As it’s a direct flow-through filter, all the essential minerals like calcium, magnesium, potassium, and more are kept while filtering out the harmful contaminants.

Do take note that It’s only suitable to be used for municipally treated water.

If you simply need a good under sink water filter with a large filtration capacity and last longer, then this is the one you need, as the Woder 10K-Gen3 Water Filter is created for this purpose.

The filter comes as a complete assembled kit, so you just need to connect it to the water source and the faucet to start using it.

And if you want to have a separate faucet for filtered water, just get a valve and a faucet to complete the whole system.


  • Last longer
  • Affordable price
  • Good filtration performance
  • Quick installation
  • Great water taste
  • Less maintenance due to long filter life


  • The flow rate may get slower after a year
  • Only suitable for the municipally treated water source
  • Filtration performance may reduce gradually before reaching the 10,000 filtrations mark

10. Culligan US-EZ-4 Water Filter [Review] – Best Budget Under Sink Water Filter



  • The RC-EZ-4 filter is tested and certified by NSF International for the reduction of sediments, chlorine taste and odor, chloroform, cyst, lead, mercury, VOCs, turbidity, perfluorinated chemicals (PFOA & PFOS), and more
  • The EZ-change replacement filter cartridge allows you to change the filter easily with the quick-connect fittings
  • Comes with a dedicated 100% lead-free faucet
  • The RC-EZ-4 filter can last up to 6 months or 500 gallons of water filtration
  • Comes with a built-in LED filter life indicator for filter replacement
  • High water flow rate at 0.5 GPM
  • Interchangeable filter cartridge between RC-EZ-1, RC-EZ-3, and RC-EZ-4 to suit your water filtration needs
  • More

The Culligan US-EZ-4 Premium Easy-Change Under Sink Water Filtration System is an affordable single filter system that can remove most of the common contaminants, impurities, and chemicals in your tap water.

It fit easily under the sink due to its compact size, suitable for a kitchen with limited under-sink space.

The filter replacement process is fast and easy with its twist-on and twist-off filter mechanism and built-in quick-connect fittings.

If you just need basic water filtration for your home, then the Culligan US-EZ-4 is the best budget under sink water filter for you.

It provides you clean drinking water daily at a minimal upfront cost. 

Even though the RC-EZ-4 filter cartridge can only last up to 6 months or 500 gallons of filtration, its EZ Change filter mechanism makes the filter replacement process easy, quick, and hassle-free (no wrenches are required).

This under sink filtration system also comes with a nice-looking faucet and a built-in LED filter life indicator to notify you of filter replacement.


  • High water filtration rate
  • Quick and easy filter replacement
  • Certified by NSF International
  • Inexpensive


  • Limited water filtration capability
  • Moderate fittings quality
  • One lithium battery is required
  • The installation may take some time if you don’t have the basic plumbing skills
  • The nylon adaptor may cause leaking if not installed properly

Here’s What I Look For In The Best Under Sink Water Filter

The Best Under Sink Water Filter Is Effective Against Contaminants In Your Water

The best under sink water filter should be effective in removing contaminants that exist in your water.

If your water contains only chlorine and some sediments, then you probably don’t need an under-sink Reverse Osmosis System, a system consist of a sediment filter and activated carbon block is enough.

But if your water quality is bad and has a high level of TDS, then the best choice would be an under-sink RO system.

The list above consist of different type of under-sink water filtration system that targets a specific group of water contaminants to fulfill the need of different households.

The Best Under Sink Water Filter Is Durable and Made of High-Quality Materials

For a device that has constant contact with your water, it must be made of high-quality and safe materials to ensure the water you drink and use is healthy and safe.

Besides, a durable under-sink water filter allows you to use it for a longer period to save your money and hassle in finding a new one.

The Best Under Sink Water Filter Is Affordable

Product price is always a factor when comes to decision-making.

Therefore, the best under sink water filter for your home should be within or just slightly stretch from your budget.

To get the best value from your purchase, never pay for what you don’t need or an overpriced system.

What To Consider When Choosing the Best Under Sink Water Filter for Home

Looking for the best under sink water filter but was overwhelmed by too many choices in the market?

I understand.

Sometimes, it’s hard to find an under sink water filter that is great in water filtration and at a reasonable price.

That is the reason why I write this guide about finding the best under-sink water filter for your family.

Instead of just showing you a list of water filters, I also want you to learn how to select the most suitable under-sink water system for your home.

Most of the best under-sink water filtration systems consist of multiple stages, from three to seven, to offer stronger filtration and features like remineralization.

In general, the more stages of filters an under sink water filter has, the stronger the filtration performance, because each filter is designed to remove a specific contaminant.

For instance, an activated carbon filter is used to remove chlorine chemicals, a sediment filter is used to remove sediment particles, a KDF filter is used to remove heavy metals, Reverse Osmosis is used to remove dissolved solids, and a UV filter is used to remove microorganisms.

So when these filters combine into a multi-stage under sink water filtration system, it can remove all of these contaminants.

To find the right under sink water filter that is suitable for your home, here are something you need to know:

Filtration Capability

First, what kind of filtration capability do you need?

Now we are talking about filter out harmful contaminants from tap water, but what exactly are those?

In other words, what contaminants need to be removed from your water source?

If your water quality is considered good, you may just need some basic water filtration with sediment filter and activated carbon filter for sediments and Chlorine.

If your water quality is moderately contaminated, you may need to consider an ultrafiltration filter or RO system.

If it is highly contaminated with a large number of dissolved solids, like most water in the United States, the RO system is the ideal choice.

If your water is prone to viruses, then you should consider adding a UV filter as a safety measure.

Of course, you don’t need to know every single impurity in your tap water, but it’s good for you to at least know the quality of your water in brief, like whether it contains a significant amount of certain contaminants like lead, mercury, fluoride, arsenic, pesticides, etc.

The most accurate way to know your tap water is to get some water sample and send to the certified lab for testing.

Otherwise, you may read the report from your water supplier or do some testing with a TDS meter for water hardness estimation.

Here is the list of contaminants in water that need to be removed and what type of filter is designed to remove them:

  • Sediments: Polypropylene (PP) sediment filter 
  • Chlorine taste and odor: Activated Carbon filter
  • Chloramines: Specialty carbon filter media
  • Heavy metals: KDF filter, Activated alumina
  • Fluoride: Activated alumina
  • Small particles: Ultrafiltration, Reverse Osmosis
  • Bacteria: Reverse Osmosis, UV filter, Ultrafiltration
  • Viruses: UV filter, Reverse Osmosis filter

Types of Filtration Technology

Once you know about the quality of your tap water, it’s time to decide the filtration technology required.

If your water is hard, like more than 120 ppm (or 120 mg/L), it’s best to use a Reverse Osmosis system to greatly reduce the total dissolved solids (TDS) in water.

If your water is soft, like less than 60 ppm (or 60 mg/L), the Reverse Osmosis system is a bit overkill, and I’ll suggest you go for a combination of sediment filter and activated carbon block. Additional ultrafiltration (UF) can be added to the filtration system for stronger protection (optional).

If you’re using well water or a poor-quality water source that is vulnerable to viruses, a water filtration system with an ultraviolet (UV) lamp is strongly recommended.

If your tap water contains an excess amount of cations (eg: magnesium, calcium) or anions (eg: nitrate, arsenic), then Ion-exchange (IX) system is an effective method to remove those ions.

Also, most of the time (if not all), you’ll need a sediment filter as a front layer of filtration to block the larger particles (eg: rust, sand, stone, etc.) and an activated carbon filter to treat chlorine taste and odor, so these two are like the defaults in a multi-stages water filtration system.

Filtration Performance

Alright, after you’ve decided the type of filters that you need, it’s time to dive in deeper on the filtration performance required.

For instance, if you’re getting an under sink Reverse Osmosis system, how many stages of filtration do you want or need?

For instance, a basic setup would be a 3-stage Reverse Osmosis system: 

Sediment + Activated Carbon Block (ACB) + Reverse Osmosis membrane

An upgraded version would be a 4-stage Reverse Osmosis system:

Sediment + Granular Activated Carbon (GAC) + Activated Carbon Block (ACB) + Reverse Osmosis membrane

Note: The double activated carbon filters are used to prevent chlorine chemicals from reaching the RO membrane for a longer lifespan.

Or a max performance 6-stage Reverse Osmosis system:

Sediment + Granular Activated Carbon (GAC) + Activated Carbon Block (ACB) + Reverse Osmosis membrane + UV filter + GAC

Note: The post-UV lamp is used to kill any potential bacteria that grow inside the RO tank and escaped viruses, and the last GAC filter is used to remove residual taste and smell from the filtered RO water.

Theoretically, it can go more than 10 stages of filtration and you can also find those in the marketplace, but I wouldn’t recommend you to get a water filtration system that goes beyond 6 stages of filtration (excluding additional features like mineralization).

That’s too much and the excess filters are redundant with no real contribution.

Water Flow Rate

Each under sink water filter will have its maximum water flow rate in GPM, indicating how many gallons of water they can filter in a minute, so if this matters to you, then choose the one with a higher filtration rate.

For RO under sink water filters, the one that offers the highest water flow rate is the Waterdrop Reverse Osmosis WD-G3P600-W at 600 GPM, which is over 8 times faster compared to other RO systems.

Filter Capacity

I believe nobody is enjoying changing the filter cartridges under the narrow sink area, so it is better to buy larger capacity filters that can last longer.

To reduce the maintenance frequency of the under sink water filter, you can install a whole house water filter to share the burden with all point-of-use water filters.

The lifespan of the filter cartridge depends on their capacity and your water usage.

Here is the general lifespan of each type of filter:

  • Sediment filter can last about 3 to 6 months
  • The activated carbon filter can last about 6 to 12 months
  • Reverse Osmosis membrane can last about 2 to 3 years

Feedwater Pressure

Most under-sink water filters require a certain level of water pressure to operate effectively, especially the Reverse Osmosis system.

If the water pressure is low, consider getting a water pump to boost it.


If you prefer the taste of mineral water, then the APEC Top Tier Supreme RO-PH90 and Home Master TMAFC-ERP Artesian are the best under-sink water filters for you.

The re-mineralized water contains essential minerals and is alkaline and has a better taste.

Size of the Under Sink Water Filter

Unless your kitchen has a large under-sink space, the filter size is something you need to take into account when considering the best under-sink water filter.

Generally, the more stages of filters, the larger the under sink water filtration system and require a larger under-sink space.

Also, the Reverse Osmosis under-sink system will need a larger space to accommodate the water tank unless you use a tankless RO system.

Additional Features

Are you a fan of alkaline or mineral water?

No problem.

If you’d like to have more of certain minerals in your filtered drinking water, you can consider getting a multi-stage water filtration system with mineralization stages to add minerals into the filtered water.

With the flexibility of the under sink water filtration system, you can build an ideal water filtration system that is dedicated to your home.

Price of the Under Sink Water Filter

Before getting too excited with the filtration performance and features, what’s your budget by the way?

It’s the fact that the price tag is always an important deciding factor in purchase consideration, so take your time and think about your budget.

How much money are you willing (or capable) to pay for a water filtration system for your family members’ health?

Generally, the more powerful the water filtration, the more expensive the under-sink water filter is.

In short, you get what you pay for.

For the health of your family, I think the price of getting the best under sink water filter is worth it.

If budget is not a big concern for you, I’ll recommend you to get the best under sink water filtration system for your family, it’s definitely worth the investment.

If your budget is tight, no worry, just get a great water filtration system within your budget.

Anyway, getting a water filter is already the right step towards more saving in the long term.

But anyhow, you shouldn’t pay for something you don’t need, like extra features or extra stages of filters that do not offer significant value.

If you want the strongest filtration system in the market, look for a multi-stage under sink Reverse Osmosis water filter.

Do You Need an NSF Certified Under Sink Water Filter?

Based on my experience, most of the best under sink water filters come with the NSF certification.

If an under sink water filter can get the NSF certification, that means its filtration performance is tested to be effective against the specific type of contaminant.

Want peace of mind? Use an NSF-certified under-sink water filter.

How Do Under Sink Water Filters Work?

The under-sink water filters force the untreated water to pass through every stage of filtration before reaching the existing water faucet or a new faucet.

Each layer of filtration will remove a certain group of contaminants.

In this way, there is no escape from the contaminants and you will only get the cleanest and safest water.

Types of Under-Sink Water Filters

There are three different types of under-sink water filters, which are:

  • Simple under sink water filters
  • Conventional under sink water filters
  • Reverse Osmosis under sink water filters

Simple Under-Sink Water Filters

The simple under-sink water filters will connect to your existing water line and faucet.

They are easiest to install and provide clean water for all kinds of usages like drinking, washing, and cooking.

It’s also one of the most popular kitchen sink water filter setup.

But the drawback is because there is no dedicated faucet for filtered water and you are using the clean water for all purposes, the filters’ life is shorter and needs to be replaced more frequently.

Conventional Under-Sink Water Filters

The setup is similar to simple under sink water filters, but the difference is that the conventional under sink water filters have a dedicated faucet to serve filtered water.

This gives you the option to use filtered and unfiltered water and directly improve the lifespan of the under sink water filter.

Besides, with a conventional under sink water filter, you can use hot unfiltered water together with cool filtered water.

The drawback is that it requires additional installation of the dedicated faucet on the countertop.

Reverse Osmosis Under Sink Water Filters

The Reverse Osmosis under sink water filters consists of multiple stages of filters along with the RO membrane and water tank to hold filtered water.

They are the most powerful under sink water filtration system that produces the cleanest and purest water.

They also come with a dedicated faucet to preserve the RO filtered water for drinking.

The drawbacks are they need extra under-sink space for the water tank and produce wastewater in the process. 

Types of Filters in Under-Sink Water Filtration Systems

Few types of water filters commonly incorporate into the under-sink water filtration systems, and they are:

  • Sediment filter
  • Activated Carbon filter
  • Ultrafiltration filter
  • Reverse Osmosis filter
  • Alkaline filter (or mineralization filter)

Sediment Filter

The sediment filters are used as a front-line defense of most under sink water filters to remove sediments and large particles to protect and extend the lifespan of the rest filters.

Besides, a sediment filter is vital to improve the filtration efficiency of the whole under sink water filtration system.

Without the sediment filter, the main filters will get clogged faster and reduce effectiveness.

Activated Carbon Filter 

Most of the best under sink water filters (if not all) use one or two activated carbon filters to deal with chlorine taste and odor, gases, and chemicals.

Activated carbon filters are one of the most popular filters in water filtration applications.

Ultrafiltration (UF) Filter

The ultrafiltration membrane is a sub-micron membrane that allows only the tiniest contaminants to pass through and remove the rest contaminants including bacteria.

The filtration performance of a UF membrane is not as strong as an RO membrane, but it provides a higher water flow rate and does not produce wastewater in the process.

The advantages make the ultrafiltration filter a great choice to treat moderately contaminated water, while the Reverse Osmosis filter is the perfect choice for both moderate and highly contaminated water.

Reverse Osmosis Filter

Reverse Osmosis filters are the powerhouse in water filtration which offers the strongest water filtration.

It can remove 99.9% of the contaminants including total dissolved solids (TDS).

You will often see this RO filter in the best under sink water filtration systems.

Alkaline Filter (or Remineralization Filter) 

Alkaline filters or remineralization filters are usually placed after the Reverse Osmosis filter to add minerals to improve water taste and pH level.

By combining the Reverse Osmosis filter and remineralization filter, you get to enjoy the safest and tastiest drinking water.

Under Sink Water Filters vs Countertop Water Filters

Under-sink and countertop water filters are the two common types of water filtration systems.

The under sink water filters are preferred by more families as the countertop spaces are more premium and limited.

Besides, the under sink water filter is also a better choice in terms of aesthetics.

Advantages of Under Sink Water Filters

Here are the advantages of under sink water filters:

  • Under-sink placement
  • Strong water filtration
  • More choices

Under-Sink Placement

Usually, the under-sink space has less usage other than putting soap, dishwasher, and allocated pipes.

By choosing the best under sink water filter for your home, you can free up the premium countertop space to put your kitchen appliances and tools.

Strong Water Filtration

Under sink water filters come with multiple filters that offer stronger water filtration capabilities in removing a wide spectrum of harmful contaminants.

Want the best quality of water? Choose the best under sink water filtration system.

More Choices of Filtration Stages

Under sink water filtration systems come with more choices for different needs, whether you want to get rid of Chlorine, Chloramines, heavy metals, viruses, or total dissolved solids.

You can choose according to your water quality.

Disadvantages of Under Sink Water Filters

  • Larger in size
  • Installation and maintenance take a longer time

Large in Size

Under sink water filters are large and bulky, which need a large under-sink space to accommodate them.

Installation and Maintenance Take Longer Time

Because under sink water filters consist of multiple filters, the installation and filter replacements will take a longer time.

If you do not have any basic plumbing skills, the installation of an under sink water filter would be challenging for you too.

Also, changing filters under the kitchen sink area is harder physically compared to the countertop.

The 5 Reasons Why Should You Buy an Under Sink Water Filter

First, the best under sink water filter offers stronger water filtration to provide you the best quality of water for drinking and other use.

Second, an under sink water filtration system will not take up any countertop space in your kitchen.

Third, an under sink water filter can be hidden underneath the kitchen sink for aesthetic concern.

Fourth, you are looking for a water filter for one single sink and not the entire house.

Fifth, by having an under sink water filter, you no longer need to buy and stock up bottled water, which saves you lots of time and money.

Under sink water filters are great, but not all of them are equal in terms of value, filtration performance, and quality.

Make sure you read the best under sink water filter reviews before buying.

The under-sink Reverse Osmosis water filters are some of the most popular filtration systems that are sought by many families due to their superior filtration performance.

RO-based water filtration systems are the best under sink water filters in terms of filtration performance.

Here are common stages of a Reverse Osmosis under-sink water filtration system:

  1. Sediment filter – To remove large particles.
  2. Activated Carbon filter – To remove Chlorine chemical as the RO membrane is vulnerable to Chlorine.
  3. Reverse Osmosis membrane – To remove most of the contaminants including total dissolved solids (TDS).
  4. Remineralization filter – To add essential minerals into the water to improve the taste and pH level.
  5. Post Activated Carbon filter – To remove any residual odor and contaminants and improve water taste.

Reverse Osmosis under-sink water filters are the most powerful filtration system that removes a large spectrum of harmful contaminants.

While they have some disadvantages like a higher price, lower flow rate, and produce wastewater, the benefit of having top-quality drinking water is unmatched.

Looking for the best RO under-sink water filter with mineralization? I’d highly recommend the APEC Top Tier Supreme RO-PH90.

If you are willing to top up a bit more for a much faster flow rate, less water waste, and tankless, then the Waterdrop Reverse Osmosis WD-G3P600-W fits your requirement perfectly.

Best Under Sink Water Filter Brands

Here are the best under sink water filter brands that manufactured the top-quality under sink water filtration systems:

  1. APEC
  2. Waterdrop
  3. Home Master
  4. Express Water
  5. iSpring
  6. Woder
  7. Culligan

These brands are popular and well-known with their high-quality water filters.

How to Install an Under Sink Water Filter?

If you have no basic plumbing skills, I’d advise you to hire a professional plumber to avoid the wrong installation and leaking problems.

If you have some plumbing skills and knowledge, here is the installation guide for the under sink water filters:

  1. Shut off the main water supply.
  2. Mark the designated area to install the under sink water filter.
  3. Drill and attach the filter tightly with screws.
  4. Attach the water tube into the inlet of the under sink water filter.
  5. Connect the outlet of the filter to the water filter with a water tube.
  6. Make sure every connection is tightened and turn on the main water supply.
  7. Check if there is any leaking and flush the system for 20 to 30 minutes before using it.
  8. Done!

If you are using a new dedicated faucet for filtered water, just install a tee fitting on the water pipe and follow the above steps.

Make sure you follow the installation manual given by the manufacturer or seller before installing the under sink water filter.

Comparison of the Best Under-Sink Water Filters of 2023

Here’s the comparison of the top 10 best under sink water filtration system:

NameStageFlow RateBest forPrice
Waterdrop WD-G3P600-W8600 GPDOverallShow
APEC Top Tier RO-PH90690 GPDRO waterShow
APEC WFS-100031 GPMValueShow
Home Master TMAFC-ERP675 GPDWater efficiencyShow
iSpring CU-A440.56 GPMUltrafiltrationShow
iSpring RCC7AK-UV775 GPDRO with UVShow
Express Water RODI10D6100 GPDWater PurityShow
Express Water ROALK5D1050 GPDAlkalinityShow
Woder 10K-Gen312 GPMLong-lastingShow
Culligan US-EZ-410.5 GPMBudgetShow

FAQ for the Best Under-Sink Water Filters

Here’s the answers for the frequently asked questions regarding under sink water filter:

1. Can I straight away drink the filtered water from a newly installed water filter?

No. A newly installed system may have residues or cloudiness, which require flushing before use.
Once you have installed a new water filter, you need to flush the system for 10-45 minutes or 5 to 10 gallons of water, depending on the water filter.

2. Why my filtered water have black flakes or grey in color?

No worries, It’s normal for the first few times if you are using a water filtration system that contains carbon block filter.

The greyish color is due to the black color carbon block and the black flakes are from the newly manufactured carbon block.

Just open the water tap and flush the system for about 5 minutes and 2-3 times will do.

3. Why the TDS value I measured is not much difference between tap water and filtered water?

Because a flow-through water filter (non-RO) will retain the minerals in water which contribute to TDS value, therefore, the TDS reading will not drop much if your tap water is treated and soft.

TDS value is only applicable to estimate the effectiveness of a Reverse Osmosis system.

4. Can a TDS meter really measure the Total Dissolved Solids in the water?

The answer is no.

I have seen many people used a TDS meter or TDS pen to measure Total Dissolved Solids in their water without knowing what is really being measured.

In short, what TDS meter measured is the electrical conductivity (EC) in water (pure H2O has virtually zero EC), and then times the EC value by a factor between 0.5 to 1 (set by the manufacturer) to estimates the TDS (which is not the real Total Dissolved Solids in water).

For instances, dissolved organic solids (eg: sugar) and microscopic solid particles (eg: colloids) are not measurable by the TDS meter because they do not affect the water conductivity significantly.

The accurate way to measure the actual TDS in water is to evaporate the water and then weighing the dissolved residue left.

5. Is the water filter brand important?

Not absolutely but is recommended if it’s a highly reputable brand in term of product safety, quality control and customer support.

As we discussed earlier, the important parts of considering a water filter system are about the material of the components, where the components are manufactured, and the functionality of the filter system.

So more importantly, choose a water filter system which all its components are manufactured by reputable companies with strict material control and strict quality control (eg: US-based manufacturers).

6. If the water filter is “Made in USA”, is that mean it’s 100% safe and good?

Not really. For example, a water filter company bought all the low-quality components from elsewhere and assembled in the USA, the company is allowed to say the water filter is “Made in USA”, but this doesn’t justify the product quality and safeties.

What you really need to know is where the components (which used to build the water filtration system) are manufactured. For instance, if all the components are made in the USA and assembled in Thailand, then the water filtration system is considered safe.

7. Is NSF certification required?

The answer is no, but it’s recommended to have NSF certified for all components that have contact with water (especially for smaller brands).

NSF is a certification system and not a quality control system, so it can’t guarantee the filter performance in the long run and the quality of your filter when it’s manufactured (since thousands of filters are being manufactured and shipped to customers directly without going through NSF).

8. How to know whether the filter cartridge is clogged or it’s time to replace?

You can measure the pressure drop by installing pressure gauges before and after the filter.

When the filter cartridge is new, run the water filtration system and write down the difference of pressure reading (let’s say 2 psi). Then measure again after a few months, you’ll notice the pressure difference is increasing, let’s say to 7 psi.

When the difference of 2 pressure gauges reading reach about 15, it’s time to change the filter cartridge (or wash if it’s washable).

9. How long can your water filter cartridge last?

For safety wise, any filter cartridge that is not washable should change every 1 year (maximum) except sediment filter which required to change more frequently (2-4 times a year depending on water quality).

While for the RO membrane, the lifespan is about 2 years since it gets washed constantly.

10. Is RO water bad for you?

No, RO water is simply the purest drinking water. There’s no solid scientific proof or research shows that RO water is bad for you.

Conclusion: The Best Under Sink Water Filter Is Filter That Removes Targeted Contaminants In Your Water And Is Priced Reasonably

Have you found the best under sink water filter for your home already?

I hope you did, trust me, each of the top 10 best under-sink water filters in the list is worth getting for your family, it is just which one is more suitable for your requirements.

Installing an under-sink water filter in your home can supply your whole family clean and safe drinking water, this benefit alone is worth your investment.

Back to you, which of the best under sink water filtration systems are you going to buy for your family?

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2 thoughts on “10 Best Under Sink Water Filters of 2023: Consumer Report”

  1. Out of the 10 recommended filters, the tankless RO really catch my attention, compact size with good filtration rate as a RO filter = Win.

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