Looking for an under sink water filter to remove chlorine, lead, sediments and other contaminants from your drinking water?
You’ve come to the right place.
An under sink water filter is the best choice if you need to treat water for drinking, making coffee, cooking and other kitchen activities.
In this buying guide, we review the best under sink water filters for removing a wide range of chemicals and impurities from water you use to drink and wash dishes. We also explain how to install and maintain an under sink system and provide answers to frequently-asked questions.
Undersink water filters are point of use filters, meaning they treat water at a specific access point in your home - usually in your kitchen.
Pitcher water filters and faucet water filters can be used in lieu of an under counter water filter, but you'll generally get much cleaner water using an under sink unit.
Top 6 Under Sink Water Filters 2023
APEC WFS-1000
OUR TOP PICK
3 stage filter
90 gals/day
18 x 12 x 10 inches
$$$
iSpring RCC7AK-UV
BEST REVERSE OSMOSIS FILTER
6 stage filter
75 gals/day
14.5 x 5.2 x 19.5 inches
$$
CuZn UC-200
BEST HIGH CAPACITY FILTER
3 stage filter
75 gals/day
4.5 x 4.5 x 15 inches
$$$
Aquasana AQ-5300.55
BEST SMART FILTER
3 stage filter
90 gals/day
4.2 x 12 x 12.9 inches
$$
Home Master TMHP
MOST WATER-EFFICIENT RO
7 stage filter
75 gals/day
12 x 16 x 20 inches
$$$
Home Master TMAFC-ERP
Best for drinking water
7 stage filter
50 gals/day
12 x 16 x 20 inches
$$$$
Frizzlife MK99
Best budget
2-stage filter
2 gals/min
5 x 5 x 13.5 inches
$
HQUA-OWS-6
Best UV filter
1-stage filter
6 gals/min
22.8 x 2.5 x 2.5 inches
$$
Woder WD-10K-DC
Best lead filter
1-stage filter
3 gals/min
12 x 2.5 x 2.5 inches
$
Best Under Sink Water Filters: Reviews
1. Our Top Overall Pick: APEC WFS-1000 Super Capacity Premium Quality 3 Stage Under-Sink Water Filter
The APEC WFS-1000 is one of the most popular and highest rated under sink water filters sold anywhere - and for good reason.
It consists of 3 stages of filtration, two of which use activated carbon blocks to completely remove chemicals and odors from your tap water.
If you don’t want to spend a lot of money on an expensive reverse osmosis (RO) system, I highly recommend this filter. It doesn't remove as many impurities as an RO system, but it's adequate for treated city water.
It is easy to install – no need to spend more money on a plumber. It even comes with most of the tools you’ll need.
The main complaint from customers is that the instructions are a bit confusing. But since installation is straightforward, you won’t have much trouble understanding which part goes where.
Pros
Cons
Best Features
3-stage filtration: The first stage consists of a sediment filter that removes rust, sand and dust from the water. The polypropylene filter has an extended dirt-holding capacity to increase lifespan. The other two stages consist of activated carbon that removes chlorine taste and odor, cloudiness and chemicals.
12+ months filter lifespan: For an average family, the filters can last 12 months or more. This reduces the number of filter replacements you have to make, which saves you time and money.
Fast water flow: The water pressure from your faucet doesn’t suffer noticeably even with the three stages of filtration.
Double carbon filters: Having two carbon filters increases filtration performance, ensuring your water is cleaner, healthier and better-tasting.
Easy installation: Most customers had no trouble installing the unit under their sink. The instructions are a bit fuzzy but you’ll figure out everything in no time.
Issues and Limitations
Ineffective Against Dissolved Solids
The APEC WFS-1000 does not remove dissolved solids from water. These include hardness minerals like calcium and magnesium and metals like iron.
If your water is hard, you’ll have to get a separate under-sink or whole house water softener.
If you’ve been seeing rust deposits on your utensils and surfaces, you’ll have to look for a water filter specially designed to remove iron.
This makes the APEC water filter less than ideal for use in homes that receive well water.
Avoid this one if: You receive well water. It contains dissolved solids that this filter cannot remove. It’s also not ideal if your main concern is bacteria in water. The filter does not remove or kill microbes.
Bottom Line
The APEC WFS-1000 water filter is great for anyone looking for a high-performance and easy-to-install under-sink water filter to remove chlorine, sediment and chemicals from their tap water.
2. Best High-Capacity Carbon Filter: CuZn UC-200 Under Counter Water Filter
The CuZn UC-200 is one of the highest-rated under sink filters sold on Amazon with 500+ customer reviews.
The CuZn UC-200 turns cloudy, chlorine-tasting and chemical-laden water into clean, clear and safe drinking water.
This filter is designed to clean about 50,000 gallons of water - about 5 years of use - before you need to replace it.
The UC-200 uses three stages of filtration, all contained in one cartridge. This makes installation easy and ensures the filter does not affect your faucet’s water pressure.
Note: this system is larger and heavier than it looks in the images. Measure carefully, because you may have trouble fitting it under your sink.
Bonus: verified customers on Amazon praise the company’s customer service as much as the product.
Pros
Cons
Best Features
3-stage NSF-certified filtration: This under-sink filter consists of three stages. Micro-sediment membranes remove small particles of dust, rust and silt. A Coconut Shell Carbon filter removes chlorine and chemicals. A KDF-55 filter removes heavy metals like lead and inhibits the growth of bacteria and mold.
High capacity: The CuZn UC-200 has a surprisingly high capacity for its price. It can filter up to 50,000 gallons of water, which translates to about 5 years for an average family. No hassles and extra expenses replacing the filter every few months.
DIY installation: There is no need to hire a plumber to set up this under-sink filter. The instructions are very clear and easy to follow. They also have an installation video on YouTube.
You don’t need to install an extra faucet for this filter. It connects directly to your cold water line. All the parts you need are included in the package.
The only tool you need to have on hand is an adjustable wrench to tighten the connections.
Excellent customer service: The almost-perfect rating is not because the filter is flawless. It has a few issues and there were several complaints from customers. But the company’s handling of complaints is amazing.
If you encounter any issue, they’ll give you a refund, send you a new unit or do whatever it takes to help you solve it.
It’s nice to see such high quality customer service from a major manufacturer.
Issues and Limitations
1. Size
The main issue with this unit is its size. It’s bigger than most people expected, making it difficult to fit it under the sink.
But most customers were eventually able to install it.
2. Ineffective Against Dissolved Solids
As for other limitations, this filter cannot handle well water. None of the three filtration stages can capture dissolved solids found in plenty in well water.
Avoid this one if you receive well water. This filter cannot remove iron and other dissolved solids found in well water.
Bottom Line
This filter is great for anyone who needs a high-capacity water filter they won’t have to replace for years. It’s also great for large families, restaurants and cafes where water consumption is high.
3. Best Smart/Connected Under Sink Water Filter: Aquasana AQ-5300.55 3-Stage Under Sink Water Filter
The Aquasana AQ-5300 combines an excellent 3-stage filter with connectivity to a smartphone app that lets you track the number of gallons filtered and sends you filter replacement reminders.
The filter itself is a 3-stage system that can handle a wide range of contaminants except dissolved solids and water-borne bacteria.
Pros
Cons
Best Features
3-stage filtration: Stage 1 consists of a 20-micron pre-filter that catches sediment, rust, silt and dust particles. Stage 2 is an activated carbon filter that removes chlorine and a variety of other chemicals from water. Stage 3 consists of a catalytic carbon filter that reduces chloramines and heavy metals.
Dedicated faucet: You’ll need to install a dedicated faucet for the Aquasana filter. But at least it’s included in the package. All you need to do is drill a hole in the sink and install the faucet. You have three finish options for the faucet to match your home décor: oil-rubbed bronze, brushed nickel and chrome.
Easy installation: Installation takes a bit more time than other filters because of the faucet. But you don’t need to hire a plumber.
The instructions are very clear. As long as you have the right tools, it takes about an hour to have your filter ready and the new faucet running.
Issues and Limitations
1. Doesn't Filter Bacteria, Cysts or Viruses
If you are planning to use this filter to treat drinking water, note that it does not remove bacteria, cysts and viruses.
So make sure your water is already safe to drink. If you are concerned about these bugs, I recommend a reverse osmosis, UV or ceramic water filter.
2. Does Not Remove Dissolved Solids
Another limitation is that the Aquasana AQ-5300 does not remove most dissolved solids. So it wouldn’t be effective on well water.
It’ll only help with sediment and some chemicals but will not remove iron, manganese and hardness minerals like calcium.
Avoid this one if you receive well water in your home. It is also not the best choice if you want to neutralize bacteria and viruses in your drinking water.
Bottom Line
This filter is great for anyone looking for a high-performance under-sink water filter that can remove chlorine, chloramines and a wide range of chemicals.
4. Best Reverse Osmosis Filter: iSpring RCC7AK-UV Deluxe Under Sink 6-Stage Reverse Osmosis Drinking Water Filtration System
The iSpring RCC7AK-UV combines the water purification of Reverse Osmosis with the biological-killing power of UV light to provide the purest possible drinking water.
Reverse osmosis is one of the most effective ways to filter-out bacteria, viruses, hardness minerals, heavy metals, rust, chlorine and a wide range of chemicals. But still, some small viruses and bacteria can still get through RO filter media.
Adding UV filtering after the RO filter kills any remaining biologicals and prevents them from entering your drinking water.
So if you are looking for the absolute purest and best quality drinking water, I highly recommend buying this iSpring under sink water filter system.
The RCC7AK-UV is more expensive than other picks on this page, but it provides unmatched filtration performance.
Pros
Cons
Best Features
High-performance RO filtration: RO systems are the gold standard for water filtration. No other filter matches their performance. According to Aquasana, their system can remove 99% of over 1,000 contaminants including lead, bacteria, chlorine, sodium, arsenic and fluoride.
6-stage filtration:
Stage 1: A sediment pre-filter to remove rust, sand, dust and other particles. This filter is see-through to allow you to easily monitor accumulated sediment.
Stage 2: A carbon GAC filter removes chlorine, odors and cloudiness from the water. It also ensures chlorine doesn’t reach the RO membrane, which could damage it.
Stage 3: CTO filter removes chloramines, chemicals and VOCs.
Stage 4: The RO membrane, the heart of the system, catches any remaining contaminants.
Stage 5: A carbon post-filter removes remaining odors and tastes from the water.
Stage 6: pH filter restores water’s alkalinity and re-introduces beneficial minerals that were stripped out by the RO membrane.
Long lasting filters: The RO membrane has an estimated lifespan of 2-3 years. The other filters will last 6-12 months depending on how much water you consume. Replacing the cartridges is easy.
DIY installation: Even if you’ve never done any plumbing before, you can tackle this project in an hour or two. All the parts are included and you only need basic tools to set up the filter under your sink.
Issues and Limitations
1. Pricey
The system is more expensive than conventional under-sink filters, but it’s actually a bargain when you compare it to other RO filters that can cost $500 or more.
2. Wasted Water
One downside you’ll just have to accept with any RO system is wasted water. It’s how reverse osmosis systems work.
All the trapped salts and contaminants have to go somewhere. The system flushes them out with water.
This particular system flushes 3 gallons of water for every 1 gallon you use.
That’s why RO filters are usually installed on just one tap. A whole house system would waste too much water.
Avoid this one if you are not concerned about chemicals and/or biologicals. If your main concerns are chlorine, taste/odor and sediment, then a less expensive 3-stage carbon filter will do just fine.
Bottom Line
This filter is great for homeowners who want the highest-quality purified and biological-free drinking water.
5. Most Efficient Reverse Osmosis Filter: Home Master TMHP HydroPerfection Under Sink Reverse Osmosis Water Filter System
If you hate the thought of wasting so much water but still want RO- and UV-purified water, then the HomeMaster TMHP is a great choice.
Compared with the iSpring RCC7AK-UV, this Home Master is far more water-efficient, with only 1 gallon of water lost for each gallon consumed.
It is also more expensive.
Like the iSpring system, the Home Master filter includes a UV filter to ensure your drinking water is completely safe. In addition, it can handle well water without any problem thanks to the integrated iron pre-filter.
Pros
Cons
Best Features
Multiple stages: This system targets almost all kinds of contaminants using different types of filters. There is a sediment pre-filter, an iron pre-filter, catalytic carbon to remove chlorine and chloramines, a UV filter to neutralize bacteria and viruses and an RO membrane to catch chemicals, bacteria and other impurities.
Ideal for well water: It’s hard to find an under-sink filter that can treat well water. That’s because most filters are not designed to handle the dissolved solids found in well water, particularly iron.
The Home Master system incorporates an iron filter that not only ensures rust doesn’t become a nuisance around your home but also protects the RO membrane from damage.
Mineral re-introduction: At the last stage, the system re-introduces beneficial minerals into the water by passing it through natural crushed marbles. This greatly improves the taste of the water.
High water flow: RO systems can be frustrating to use because of their weak flow. Home Master uses wider fittings that provide a stronger flow rate.
Less water waste: The Home Master system has a water waste ratio of 1:1. It wastes less water than most other RO systems.
Issues and Limitations
1. Price
This system is expensive. But considering the extra features and high filtration performance, it’s understandable why it costs more than standard RO systems.
2. Lengthy Installation
The other issue is the long installation process. You can install the system yourself but you’ll need 2-3 hours to get it up and running.
Avoid this one if you are looking for a low-cost under-sink water filter. If you want a cheaper RO system, consider the iSpring unit above.
Bottom Line
The HomeMaster Hydroperfection filter is great for anyone who wants a high-performance RO under-sink filter that minimizes water waste. Also a better choice for homes that receive well water due to its built-in Iron filter.
6. Best Under Sink Filter for Drinking Water: Home Master TMAFC-ERP
When it comes to drinking water, reverse osmosis systems are hands down the best under sink filters. They provide a level of purification that other types of filters simply cannot match.
In addition to chlorine and various chemicals, an RO system also reduces heavy metals like lead as well as microbes like bacteria and viruses.
The best RO system for drinking water is the Home Master TMAFC-ERP. In addition to removing virtually every contaminant in water, it also mineralizes the water - twice - to make it healthier and better tasting.
If you are used to buying bottled mineral water, the Home Master TMAFC-ERP is an excellent, and cheaper, alternative.
Pros
Cons
Best Features
High-performance filtration: There’s no beating reverse osmosis when it comes to filtration performance. The TMAFC-ERP RO system uses a sediment filter, catalytic carbon and an RO membrane to remove sediment, rust, scale, chlorine/chloramines, chemicals, heavy metals, TDS and microbes from water.
Two re-mineralization points: One issue people have with RO systems is that they produce flat tasting water. That’s because all the minerals are stripped out by the RO membrane.
The TMAFC-ERP returns healthy minerals into the water at two points, ensuring you get slightly alkaline mineral water that’s only better for your health, but tastes great as well.
Permeate pump: The TMAFC-ERP comes with an integrated non-electric permeate pump that does two things: it fills the reserve tank faster so you always have drinking water, and reduces how much water goes down the drain.
The permeate pump, together with Home Master’s Fast Flo RO Kit also increases flow rate out of the faucet.
Modular filter design: Home Master RO systems have a modular design where the filter cartridge is one with the filter housing. This ensures you don't stay with the same housing for years, which can cause mould and leaking.
With Home Master, you change the housing every time you replace the filter. This increases overall system longevity and makes filter replacements so much easier.
Issues & Limitations
1. Expensive
The Home Master TMAFC-ERP costs more than other types of under sink filters. It also costs more than other under sink RO systems. If you are on a budget, consider getting an iSpring RO system or a carbon filter like the APEC WFS-1000.
2. Takes Time to Install
While the Home Master TMAFC-ERP is designed for DIY installation, setting it up takes a good 2-3 hours. That’s because you need to install a dedicated faucet. If you are busy, you may opt to just hire a plumber.
3. Wasted Water
Other types of filters don't drain any water.
RO systems need to flush the RO membrane to keep it working and the water used gets drained.
Because the Home Master TMAFC-ERP has a permeate pump, it drains less water than other RO systems (about a gallon for every gallon of purified water), but that’s still water down the drain.
Avoid this one if: You are shopping for a budget under sink water filter.
Bottom Line
The Home Master TMAFC-ERP RO filter is great for anyone looking for the most effective under sink filtration system for drinking water that eliminates almost all impurities including germs.
7. Best Budget: Frizzlife MK99
If you are shopping on a budget, the Frizzlife MK99 is one of the cheapest under sink water filters. It’s a 2-in-1 system that reduces some of the most dangerous contaminants in your water including lead, various heavy metals and chemicals.
It also eliminates the tastes and odors caused by chlorine and other contaminants.
It costs less than $100, is super easy to install and the filter cartridge lasts 1-2 years.
Pros
Cons
Best Features
2-Stage Filtration: The Frizzlife MK99 contains a 2-in-1 filter cartridge consisting of a 5-micron sediment filter and a 0.5 micron activated carbon filter.
The sediment filter reduces silt, rust and other particulates floating in water. This clears up the water and protects the carbon filter from clogging.
The carbon filter reduces chlorine, VOCs and other chemicals, as well as lead and various heavy metals.
Fast flow rate: The 0.5 micron carbon filter doesn't slow down water flow rate out of the tap. Manufacturer specs give a flow rate of 2 GPM if your inlet water pressure is 40 PSI. However, the flow may slow down after some months as it collects contaminants. Make sure you replace the cartridge as recommended to maintain water pressure.
Easy installation: The Frizzlife MK99 is easy to install. It takes most people under half an hour to set it up. Unlike RO systems, you don't need a dedicated faucet nor do you need to connect it to the drain. So no drilling involved.
Easy maintenance: The filter cartridge lasts between 1 and 2 years depending on the quality of your water and your consumption. Bigger households or homes that get water with a high level of impurities may need to replace the filter after 6-8 months.
Changing the filter is easy; you don't even need to turn off the water since the filter has an auto-off valve. Just twist to remove the old filter cartridge and put in the new one.
Issues & Limitations
1. No NSF Certification
According to the manufacturer, the Frizzlife MK99 removes 99.99% of lead. However, it lacks NSF certification for this.
Instead it has IAPMO R&T certification. Frizzlife says the filter is certified by IAPMO to NSF 42 and 53. While IAPMO is a recognized standards and testing organization, most people trust NSF certification.
If you want the peace of mind that an NSF-certified filter provides, you may want to look elsewhere.
But we believe the Frizzlife MK99 is as good as any NSF-certified filter.
2. Doesn't Remove Microbes
If you are concerned there are bacteria and viruses in your water, we do not recommend the Frizzlife MK99. Only a ceramic filter, an RO system, or a UV filter can remove or sterilize microbes in water.
That’s why the Frizzlife MK99 is suitable only for treated city water.
Avoid this one if: You are worried your water contains bacteria, viruses and other microbes. It’s especially not suitable for homes with well water.
Bottom Line
The Frizzlife MK99 filter is great for anyone looking for a pocket-friendly under sink water filter.
8. Best Under Sink UV Filter: HQUA-OWS-6 Ultraviolet Water Purifier
A UV filter is a good choice if your main concern is microbes in water. The UV radiation sterilizes germs, rendering them harmless without adding any chemicals to the water.
The HQUA-OWS-6 UV filter is designed for point-of-use installation such as under the sink. It’s easy to assemble and install, and can handle a flow rate of up to 6 GPM.
Pros
Cons
Best Features
Effective sterilization: As long as your water is within the parameters the manufacturer recommends (iron less than 0.3ppm, hardness under 7 GPG, and so on), the UV filter is very effective at purifying the water.
Easy installation: The HQUA-OWS-6 UV filter is much easier to install compared to other types of under sink filters. You just need to connect it between your cold water line under the sink and the existing faucet. Note that you’ll need to mount the filter on the side of the sink and plug it into an outlet.
Low maintenance: Without filters to replace every few months, the HQUA-OWS-6 is easy to maintain. All you need to do is clean the glass sleeve every 6-12 months (and get a new one after 2 years), and replace the UV lamp every year.
High flow rate: The HQUA-OWS-6 UV filter allows a flow rate of up to 6 GPM, which is more than enough for a kitchen faucet. Make sure your water doesn't flow any faster than this as it could reduce sterilization effectiveness (if it flows faster than 6 GPM, you’ll need to install a regulator/restrictor).Issues & Limitations
1. No Auto-off Function
Some UV filters have an auto-off/on function where they turn on only when they detect water flowing. This saves energy and lengthens the life of the UV lamp.
The HQUA-OWS-6 UV filter lacks this feature. It stays on all the time. One downside of this is that water sitting within the tube can get pretty hot if you don't use the faucet for an extended period. When you go to open the faucet, it temporarily produces hot water that can burn you.
Be careful when turning on the faucet if it’s not been used for a while. Always let the water run for a few seconds before you touch it.
2. You May Need a Pre-treatment Filter
You may need to add the cost of additional filters to your budget. The HQUA-OWS-6 UV filter only deals with microbes; it doesn't reduce any other impurities.
So if you are also worried about iron, lead, chemicals or the taste of chlorine, you’ll need to install an additional filter, either a whole house or under-sink filter.
Another reason you may need an additional filter is to make sure the water is within the required parameters for successful UV treatment.
For instance, if your water hardness is higher than 7 GPG, you’ll need a whole house water softener. If you use well water with high iron levels, you’ll need to install an iron-reducing filter.
Avoid this one if: You are concerned about multiple impurities in your water. Get an RO system instead. It’ll remove the microbes as well as chemicals and heavy metals.
Bottom Line
The HQUA-OWS-6 UV filter is great for anyone looking for a UV filter to sterilize germs in their tap water.
9. Best Under Sink Water Filter for Lead: Woder WD-10K-DC
If your water contains dangerous levels of lead (get a test to be sure), an RO system is the best choice. But an RO filter is pricey, is tedious to install and wastes some water.
If your only worry is lead, the Woder WD-10K-DC is an excellent choice. It removes over 99% of lead, reduces various other impurities, and is easy to install.
Pros
Cons
Best Features
99.9% lead reduction: Although it doesn't have an NSF certification for lead reduction (it has NSF 42 for chlorine, tastes and odors reduction, and NSF 372 for lead-free components), the manufacturer says the Woder WD-10K-DC can remove up to 99.9% of lead from water.
You can request for test data from the company. Also, customers who’ve tested their water before and after installation say it does reduce lead to safe levels.
Removes other impurities: The Woder WD-10K-DC is not a lead-only filter. It also reduces chlorine, tastes & odors, various chemicals such as VOCs, and heavy metals.
Easy installation: It takes just a few minutes to connect the Woder filter’s ⅜” fittings to your cold water valve and faucet under the sink. Unlike an RO system, you do not need a dedicated faucet (though you can install one, if you want).
Issues & Limitations
1. Relatively Low Flow Rate
The most common complaint from users is the low flow rate of the Woder WD-10K-DC. You’ll notice an immediate drop in pressure from your faucet (you might consider installing a dedicated faucet specifically for drinking and cooking water).
The Woder WD-10K-DC has a flow rate of 3 GPM at 60 PSI. If your water pressure is lower than this, you’ll get an even lower flow rate.
But most people are happy to put up with slower flowing water for the peace of mind that it is lead-free.
2. No Replacement Filter
The Woder WD-10K-DC does not have a replaceable filter. You have to replace the entire system with a new one.
Fortunately, the filter is not that expensive and it lasts for about 3 years or 10,000 gallons.
Avoid this one if: You don't have a lead problem. If you want to remove chlorine or chemicals, there are other fast-flowing filter you can get.
Bottom Line
The Woder WD-10K-DC filter is great for anyone who wants to get lead-free water from the kitchen faucet.
Do I Need an Under Sink Water Filter?
Even if you get treated city water, it could still contain a variety of contaminants like sediment, lead and chemicals.
Some of these impurities may have gotten into the water on its way to your home.
For instance, if you have an older home build before 1986 when the government mandated lead-free plumbing, you might have lead pipes that introduce lead into your water.
The amount of contaminants is even higher if you receive well water. It contains lots of dissolved solids that harden water, cause discoloration of surfaces and can sometimes be harmful.
If you want water that you are sure is safe for drinking, cooking, pets, baby food and other household activities, then you need a water filter.
You could install a whole house water filter but that will cost you more and you might have to hire a plumber to install it.
Most people opt for a point-of-access under-sink filter that’s cheaper and easier to install.
Depending on the type of filtration media, an under-sink filter can remove lots of stuff from your water.
What is an Under Sink Water Filter?
This is any water filter system that is permanently installed under the sink.
Most undersink water filters connect directly to your incoming cold water line and provide filtered water through the existing faucet or a dedicated one.
Under Sink vs. Countertop Water Filters
A countertop water filter sits on the counter and connects to the end of the faucet rather than to the water line.
It’s a good choice if you don’t have much space under the sink.
While they do require some space on the countertop, most models are small enough for even the smallest kitchens.
On the downside, countertop water filters tend to have a lower flow rate than under-sink models.
That’s not a problem if you are only filtering water for drinking.
But if you plan to use the filtered water for cooking, washing utensils and other activities, an under-sink filter is the better choice.
Under Sink vs. Whole House Water Filters
An under-sink filter is a point-of-access filter. You install it at a specific faucet.
A whole house filter is a point-of-entry filter. You install it on the main water line coming into the house.
Which one is the right filter for your home?
If you are solely concerned about using filtered water for drinking and cooking, an undersink filter will save you a lot of time and money.
But if you want also want filtered water for washing and bathing, then you’ll need to step up to a whole-house filter.
Note: Many homeowners use both types of filters, for example a single RO under sink filter in the kitchen for drinking water plus a less-expensive/no-RO whole-house filter to remove sediment, chlorine and chemicals .
3 Types of Under Counter Water Filters
In-Line Water Filters
Easiest to install, hidden from view.
The filter connects directly to the main cold water line and the filtered water is directed back into the existing faucet.
So you don’t need to install a dedicated faucet for the filtered water.
The main downside with this filter is that you have to install two of them if you also want to filter the incoming hot water.
Faucet Water Filters
Widest range of options.
The filter connects to the cold water line and the filtered water is directed to a dedicated faucet. That means you have to drill a hole in the sink for a new faucet.
Similar to a simple water filter, a conventional filter serves only one water line. If you want to filter both the hot and cold water, you have to install two separate filters and two separate faucets.
Reverse Osmosis Water Filters
For the purest drinking water possible.
Most water filters use activated carbon to remove chlorine and chemicals from water. But activated carbon does not remove bacteria and other harmful water-borne bugs.
A reverse osmosis filter removes a wide range of impurities including chemical, heavy metals and dangerous microorganism including bacteria, cysts and viruses.
How Do Under Sink Water Filters Work?
A typical under sink water filter uses multiple filtration stages is a specific sequence, usually from larger mesh to finer mesh filters. Each stage targets a specific type of impurity.
The first stage usually consists of a large-mesh / 100 micron sediment filter to remove large particles like dust and silt from the water.
The second and third stages usually consist of smaller-mesh carbon filters that capture molecules of chlorine and other chemicals.
In an RO filter, an even finer mesh RO membrane comes next to remove whatever other impurities and microorganisms the other filters missed.
Many RO filters also incorporate an alkalizing/water ionizer stage where the pH of the slightly acidic water is increased and lost minerals are added to improve taste.
Finally, some systems finish the filtering process by adding a UV filter to kill any remaining small organisms that survived earlier stages.
How To Buy The Right Under Counter Water Filter For Your Home
Here’s what to consider when buying an under-sink filter for your home.
Number of Filter Stages
A high quality under sink water filter will have at least 2-3 stages. The more stages the water goes through, the purer it becomes.
The most expensive RO filters use as many as 9 stages.
Type of Filter
Modern carbon filters are extremely good at removing contaminants from water. If your water is generally clean, then you don’t have to buy a pricey RO filter.
But if you are concerned about removing all chemicals and bacteria from your drinking water, then an RO filter is the best.
If you don't like reverse osmosis or the water waste that comes with it, the consider buying a ceramic filter. It’s cheaper and can neutralize most harmful bacteria and viruses from water. But it should be paired with a carbon filter to make sure all chemicals are removed.
Ease of Installation
Most under sink filters involve very simple DIY installation. Some may take longer than others to set up but you rarely need to call a plumber.
Check that all the connectors and hoses are included. Installation will take longer and cost you more if you have to run to the store to get missing parts.
Also make sure the filter can actually fit under your sink before you order.
Water Pressure/Flow Rate
If you are buying an RO system, don’t expect the same water pressure as before. RO systems are slower and the thin tubes significantly reduce water flow.
But this is not a major issue if you are only using the filter to treat drinking water. It doesn’t take forever to fill a glass even if the pressure is low.
However, newer RO systems such as the Home Master one we have reviewed use wider tubes and special filter designs to increase water pressure without compromising filtration performance.
Carbon filters generally have higher flow rates. They are better if you need filtered water for higher-water-volume activities like washing dishes.
Filtering Capacity/Filter Life
Most manufacturers list filter capacity in terms of months or years.
Most carbon filters last between 6-12 months while RO filters can last 2 years or more.
Some filters are rated in terms of gallons. But since it’s hard to track how many gallons of water you are using, you won’t know when to replace the filter.
Always look for the number of months or years of usage recommended by the manufacturer.
Ease of Filter & Membrane Replacement
When buying replacement parts for your under-sink water filter, I recommend you order from the original manufacturer only. There are a lot of poor quality filters sold on sites like Amazon and Ebay today. So check those prices when making a decision.
Something else to check before buying is how easy it is to change the filter.
With most under sink water filter models, you simply unscrew the cartridge, remove the old filter and put in the new one.
In some models, both the filter and filter housing are one unit. So you have to replace all of them.
How To Install an Under Sink Water Filter Properly
Depending on the type and size, you’ll need anywhere between 30 minutes and 3 hours to install an under-sink water filter.
Listed below is the general process. Check your user manual for more specific instructions.
Care and Maintenance of Under Counter Water Filters
Under-sink filters require almost no maintenance. Once you install the filter, check on it now and then to look for leaks.
After the manufacturer-recommended usage time, replace the filters are directed in the user manual.
Frequently Asked Questions About Under Sink Water Filters
Are under sink water filters any good?
An under-sink water filter removes chemicals and other harmful contaminants that are potentially dangerous for your health.
They also improve the taste of water by removing chlorine and chloramines.
What does an under sink filter remove?
It depends on the type of filter. A carbon filter will remove chemicals, chlorine and some dissolved solids.
An RO filter will remove a wide range of chemicals as well as water-borne bacteria, cysts and viruses.
Do I need to hire a plumber to install an under sink water filter?
Usually, no. Most under-sink filters require simple installation that you can do yourself.
Can I use an under sink filter with well water?
Look for a filter specifically designed to remove dissolved solids like iron found in well water.
Do I have to install a new faucet for an under sink water filter?
Not always. Some under sink filters work with the existing faucet.
How To Get The Best Deal
In my experience, the best places to shop for under sink water filters in the United States is on major retail sites like Amazon.com, Walmart.com, HomeDepot.com and Loews.com. All of these retailers offer a good assortment of high-quality products at competitive prices.
When starting your journey, I recommend shopping on Amazon due to the variety and the quality of their reviews.
Specification Chart
Disclamer: All links below go to Amazon.com
| PRODUCT | DIMENSIONS | PRICE | WEIGHT | FEATURES | SPECIFICATIONS | |
|---|---|---|---|---|---|---|
| Doulton W9330958 SuperCarb Under Sink Water Filter  | 3.5 x 3.5 x 12 inches | $$$$ | 3.2 pounds | Ceramic filter / Genuine OEM product | NSF Certified / ADA Compliant | |
| APEC WFS-1000 3 Stage Under Sink Water Filter | 18 x 12 x 10 inches | $$$ | 13.3 pounds | US MADE super capacity filter | 100% lead-free Chrome faucet / Plus NSF & FDA certified | |
| CuZn UC-200 UnderCounter Water Filter | 4 x 4 x 15.5 inches | $$$ | 7.8 pounds | 50000 gallons capacity | KDF-55 Filtration Media and Acid Washed Catalytic Coconut Shell Carbon | |
| Aquasana AQ-5300.55 3-Stage Under Sink Water Filter | 12 x 4.2 x 9 inches | $$ | 6 pounds | Alerts you when it's time to change your filters | Full system certified to NSF Standards | |
| Woder 10K-GenII Ultra High Capacity Water Filter  | 3 x 3 x 15 inches | $$ | 2.9 pounds | Last for up to 10,000 gallons | Built with NSF approved materials (NSF61) | |
| Filtrete Advanced Undersink Water Filtration System  | 4 x 6.8 x 14 inches | $ | 2.6 pounds | 6 months or 2,000 gallons filter life | Advanced Style | |
| iSpring RCC7AK 6-Stage Under Sink Reverse Osmosis Water Filter  | 14.5 x 6 x 17 inches | $$ | 20 pounds | Filter Cartridges with RO Membrane | NSF/ANSI standard | |
| APEC Top Tier Alkaline Mineral pH+ 75 GPD 6-Stage Ultra Safe Reverse Osmosis Water Filter  | 16 x 5.2 x 17.5 inches | $$ | 25 pounds | Premium long lasting filters | Supreme quality | |
| Watts Inline Water Filter  | 10 x 2.5 x 2.5 inches | $$$ | 3.7 pounds | Lasts up or 20,000 Gallons | NSF Certified for 20,000 gallons | |
| iSpring RCC7AK-UV Deluxe Under Sink 7-Stage Reverse Osmosis Drinking Water Filtration System | 14.5 x 5.2 x 19.5 inches | $$ | 31 pounds | NSF/ANSI standard resulting in WQA Gold Seal certification | ||
| Home Master TMHP HydroPerfection Undersink Reverse Osmosis Water Filter System | 12 x 16 x 20 inches | $$$ | 18.75 pounds | Advanced long lasting filters upto – 2,000 gallons | NSF (National Science Foundation) standards | |
| Culligan US-EZ-4 EZ-Change Undersink Drinking Water Filtration System  | 14.2 x 9.2 x 8.4 inches | $ | 4.05 pounds | Can filter up to 500 gallons of water | Independently Certified by the NSF |
Learn More!
Check out our other popular water treatment guides on this site:
