Best Under Sink Water Filters 2021 – Buyer’s Guide

While the United States is close to having the best water source in the world, there are sill chemicals like chloramines and hazardous pollutants like petrochemicals that can get into your water supply.

With the best under sink water filter, you can eliminate these threats and have healthy, sustainable water anytime.

Best Under Sink Water Filters 2023

1 Home Master Artesian Full Contact Reverse Osmosis System – Best Reverse Osmosis Filtration

Home Master Artesian Full Contact Reverse Osmosis System

Picky water drinkers rejoice!

The Homer Master Artesian Full Contact Reverse Osmosis System is a very reliable system that produces extremely pure water. The taste is amazing.

You can easily change the filters once installed. The permeate pump allows you to conserve more water as well.

However, it may take you awhile to install, especially if you have granite counters and want to install it as a completely custom faucet.

This system has a modular filter design that allows for efficient water use with a faster flow.

Some water pumps tend to have an electrical aftertaste, but because Home Master designed a non-electrical permeate pump, you get incredible water while reducing waste at the same time. There are very few water filtration systems that can achieve this.

While the DIY installation can be difficult, Home Master also provides a customer support line that helps you through any difficult setups.

You basically attach your line to the pump, but if you want to mount it inside of your cabinet, then you may take additional steps to fix it.

The set comes with everything you need including the reverse osmosis membrane, feed-water adapter, chrome faucet, RO adapter, drain saddle, and storage tank.


There are a lot of advantages to a reverse osmosis system like this one from Home Master.

The set up is pretty straightforward if you have the appropriate line under your sink.

These systems use long-lasting filters, so you won’t have to change it for a year or more. We liked that the faucet has a faster flow rate while still maintaining great water efficiency.

Overally, this is an excellent choice for anyone who wants guaranteed pure water out of the tap.


  • Amazing, clean water
  • More water efficiency
  • Fast flow rate
  • Non-electrical permeate pump


  • DIY installation may take an hour or more depending on your plumbing knowledge
  • Lots of parts, so keep note what everything is with the manual


2 Woder 10K-Gen3 Ultra High Capacity Water Filtration – Best for Easy Installation

Woder 10K-Gen3 Ultra High Capacity Water Filtration

While the Woder 10K-Gen3 is easy to install and won’t break your bank, we also felt that the water just didn’t taste as filtered as a reverse osmosis system.

Still, that shouldn’t deter you from purchasing this filter, it’s best for filtering out chlorine and petrochemicals. However, it does a mediocre job of filtering out lead.

We may be picky about water, but the Woder also wasn’t able to filter out a lot of minerals, which contributes to the taste.

We may be picky about water, but the Woder also wasn’t able to filter out a lot of minerals, which contributes to the taste.

Despite our findings, most customers like the price point and taste of this water. The system is very easy to install, and the filters last for 10,000 gallons.

There aren’t any plumbing skills required to hook up this system either. You can use a direct connect hose that hooks right into your normal sink setup.

One of the great things about this filter is the flow rate. This system scored extremely high for its ability to pump out filtered water. It was actually one of the fastest in the group.


Overall, the Woder has some problems that will challenge the pickiest of water lovers.

While it fits into most people’s budgets, the filtration isn’t as good as some of the filters that are in the same price range.

However, we appreciate how quickly it is to install this filter despite its middle-of-the-road performance.


  • Great value
  • High flow rate
  • Filters out most chemicals like chlorine
  • Easy installation, no plumbing required


  • Mediocre filter for lead and minerals


3 CuZn UC-200 Under Counter Water Filter – Best Filter for Urban Homes

CuZn UC-200 Under Counter Water Filter

One of the most impressive features of this filtration system is its long-term value.

CuZn promises that you won’t have to change the filter for 50,000 gallons or what amounts to five years.

However, there are a few things to note about this system. It won’t work with wells, and it only works on cold water.

Basically, if you live in the city and want to filter municipal water, this is the best choice for a budget-friendly filtration system.

The CuZn uses a three-stage filtration process, so it has incredible performance on all tests.

It was able to filter out chlorine, lead, petrochemicals, and minerals, gaining a pretty high score over all the other filters we tested.

This is because CuZn actually uses something totally new called the “virgin acid washed coconut shell carbon,” which makes it impervious to mold and bacterial growth that can harm other carbon filters.

In addition, the CuZn is easy to install, and you won’t need any professional tools to hook it up to your faucet. In fact, you can probably install this in just 5 minutes and have pure, great-tasting water.


Overall, we love that this filter is so easy to install and performs so well in filtering out every chemical. While some filters skimp on lead and mineral filtering, this is the perfect filter to get everything out of your municipal water.

While it won’t work with any well or hot water, you should be able to get great drinking water and cooking water for your home using this filter.


  • Great for urban homes
  • High filtration for all chemicals
  • Easy to install in under five minutes


  • May be a bit pricey for those who want under $50 filtration systems


4 APEC Alkaline Mineral GPD 6-Stage Reverse Osmosis Filter – Best Tasting Water Filtration

APEC Alkaline Mineral GPD 6-Stage Reverse Osmosis Filter

This is one of the most highly rated reverse osmosis filtration systems on the market.

That’s because it uses an ultra-purifying 6-stage process to clean water.

In fact, this filter removes almost all of the contaminants in your water, so that you are left with the purest drinking water possible.

APEC also makes it install their filters, so this APEC GPD filter is no exception. This model comes with everything you need to install in just a few minutes, including pre-drilled holes if you want to install it to the side of your cabinet.

The water pressure is also stable with this model. While some filters may clean the water, it’s rare to find one that actually has the same flow output as your faucet.

This one by APEC has a great flow rate and produces clear, possibly the most pure water that we have tested yet.


If you have the budget for the APEC 6-Stage Under the Sink Water Filter, then you definitely have the best water.

This is a great investment for your home if you want to have pure drinking water that works with every kind of faucet and water system.

You can easily install this to work with municipal and well systems, and it received the highest scores for filtering out chlorine, lead, minerals, petrochemicals, and radon.


  • Filters out almost all contaminants
  • Great flow rate
  • Easy to install
  • Stainless steel faucet


  • Only one faucet finish
  • You may need some tools and hardware to install on your cabinet wall, which are not included
  • Expensive


5 APEC Water Systems RO-90 Reverse Osmosis Filter – Best Performance in Water Filtration

APEC Water Systems RO-90 Reverse Osmosis Filter

This is an incredibly efficient and high scoring water filter that is able to deliver results.

This is the type of water that you could bottle up and sell because of its taste and purity. While it is one of the more expensive water filtration systems, it uses reverse osmosis and a 5-stage purification system.

In fact, this system is certified to remove 99 percent of all contaminants. We found that it was able to remove chlorine, arsenic, lead, fluoride, heavy metals, viruses, bacteria, and a variety of petrochemicals.

APEC has always focused on engineering, which is why their filters are a bit expensive.

Still, this is one of the highest-rated home filtration systems because of its performance. The filters are also guaranteed to last for years due to their high capacity.

The engineers for this system have truly thought about everything, right down to the material of the faucet. The chrome faucet is FDA certified and comes with food grade tubing.

You never have to worry about contaminants coming from your pipes or faucet. The one thing that we really about this system is the ease of installation. You can set it up in less than 5 minutes with any typical kitchen sink or bathroom sink setup.


Like the other APEC system, the price is going to be a determining factor in whether you want long-term, pure water filtration. If you do, then you probably won’t mind making the investment into this system.

You are guaranteed to have great-tasting, purified water. As a bonus, it takes only minutes to set up this filter under your sink.


  • Delivers pure water
  • Filters out 99 percent of all contaminants
  • Uses a 5-stage reverse osmosis filtration system


  • Expensive


6 iSpring RCC7AK 6-Stage Reverse Osmosis Filtration System – Best RO Filter on a Budget

iSpring RCC7AK 6-Stage Reverse Osmosis Filtration System

It’s difficult to find reverse osmosis systems out there for under a certain price threshold.

APEC is obviously the most expensive and highly rated, but iSpring has come up in the past few years with their 6-stage reverse osmosis products.

We found that their RCC7AK Reverse Osmosis Filtration System rivalled APEC’s in its ability to filter water and provide the purest taste.

This system design uses cartridge filters. Here is where it is a little different than APEC. The cartridge filters do look a bit cheap in the plastic filter holder.

While these filters can be tricky to change, at least moreso than the Home Master’s modular filter system, you can still get the filter in and out with relatively little effort.

We found that the water efficiency and pressure were a little lacking, but it’s not noticeable unless you’ve been reviewing water filters all day.

The installation is intended to work with a feed water pressure that sits between 40 and 81 PSI. So if you have pressure lower than 40 psi, then you will need a separate permeate pump. If above 80 psi, then you’ll need to install a pressure regulator.

However, it should take you about a half hour to install this unit.


For anyone who wants a stable and purifying reverse osmosis system, the iSpring can work well.

However, we found that installation came with too many issues, and ultimately, it took longer than it should for a DIY.

If you are thinking about getting the iSpring, then be sure to check out your water pressure first to ensure that it’s between 40 and 80 psi.


  • Above average water filtration
  • Gets out most contaminants, including chlorine, lead, fluoride, heavy minerals, and petrochemicals
  • Great value for reverse osmosis system


  • Installation can be tricky, you may need to consult someone with plumbing experience


7 APEC WFS-1000 3-Stage Under the Sink Water Filter System – Best APEC for the Money

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

Perhaps you are a picky water drinker on a budget. In that case, you should still go for the APEC.

This system is designed for supreme water filtration with a long-lasting dependable filter.

In addition, it comes with a lead-free chrome faucet and works well for treating tap water, well water, and municipal water.

Unlike the 5-stage and 6-stage reverse osmosis systems, the 3-stage filtration uses a polypropylene sediment filter, carbon block filter, and a second carbon filter.

These filters work together to remove almost all of the contaminants.

While it’s not as close to pure as the 5-stage and 6-stage filtration system, it’s still a good option for urban households that want to filter out municipal water and chlorine.


When you want something that just works and gives you great-tasting water, you can trust APEC to deliver.

Even with this 3-stage filtration system, you’re able to taste the difference in your water almost immediately. It tastes fresher, and tests reveal that it is able to block out most contaminants.


  • Great value for superior filtration system
  • 3-stage water processing with multiple filters
  • Decent filtration, though not for heavy minerals
  • Easy 5-minute installation


  • Doesn’t filter as well as 5-stage and 6-stage reverse osmosis APEC systems


Benefits of Under Sink Water Filters

You have probably heard that there is “something in the water” for many years. This comes from a story that showed the US was putting fluoride into the public drinking supply.

While it was supposed to help out with tooth decay, there were a lot of other contaminants that weren’t being filtered out that caused other health problems.

The EPA does require that water suppliers provide a report to customers every year in July. This is where you can see how well your water supply is being filtered.

Typically, you’ll see that there are still contaminants like chlorine, fluoride, heavy minerals, petrochemicals, and lead traces.

The benefits of an under counter water filter cannot be stated enough. Unlike Brita filters or door filters for your refrigerator, you can get natural, purified water from the tap with an under-the-sink filter.

While this is the main benefit, we’ve found that it’s also just a great investment for your home. Many homeowners nowadays look for water installation systems that are already installed.

Here is the full list of benefits that we love about these filters:

  • Instantly remove bad odors and tastes from your water
  • Sediment removal using polypropylene
  • No chlorine in your water
  • No heavy metals
  • Trace amounts of fluoride (best when using Alumina filters)
  • No arsenic
  • Reduction in nitrites and nitrates
  • Less traces of limescale
  • Micro-organism and bacterial removal

Most people are simply looking for an easy way to get the purest drinking water to their faucets, but that’s not all you want to look for when shopping for a water filtration system.

You may spend too much on a system that doesn’t score well on contaminant removal.

The best filtration systems are able to provide a report and guarantee that they’ll be able to remove most of the contaminants in your water supply.

Types of Under Sink Water Filter & How It Works

When you start to look at your budget and what you want, you’ll be able to see what undersink filtration systems are best for your home.

We’ve compared the main under counter filters below.

Simple Undersink Filter

The main difference between a simple undersink filter and convention filter is the installation process.

These water filters process only the water from the cold water line. You don’t need to install any additional faucet as it will work with your main one.

The main benefit of these filters is their low cost and easy installation. However, their filters don’t last as long and will require that you change them more often.

You also trade off some of the filtration for certain contaminants, such as trace lead and heavy minerals.

Conventional Undersink Filter

The main difference with a convention undersink filter is the second faucet. These filters attach to your cold water line and use a separate faucet, typically made of chrome, to filter out your water.

These filters are a little bit more tricky to install because they use different fittings to attach to the cold water line. If you don’t already have an extra hole for the second faucet, you’ll need to drill one into your countertop.

Since this faucet is separate, you typically have a longer-lasting filter and can use it for drinking water or cooking water as needed without needing to change the filter for multiple years.

Reverse Osmosis Filter

Unlike the other two filtration systems on this list, reverse osmosis filtration is very different and purifies the water with multiple stages.

This allows you to get the ultimate filtration and purified water. Almost all contaminants are removed with a reverse osmosis system.

These systems use an RO membrane and come with several filters that keep out sediments and pollutants.

In addition, these systems don’t use any type of electrical pumps in filtering out the water. You will never get that metallic electrical aftertaste.

You’ll still need to check the reviews for how long these systems will last. In most cases, your RO water filter will last over two years, but it all depends on the brand and size.

One of the main things to keep in mind is that reverse osmosis systems may be the best, but they are not the cheapest. You also may need plumbing experience to install the second faucet.

Under-Sink Vs Countertop Water Filters

You might be thinking why get an undersink filter when there are plenty of cheap, countertop water filters that cost less than $20 in some cases.

For one, you should always factor in the filter cost for countertop filters, which range from $15 to $60 a pop, depending on the quality of the filtration.

In addition, some of the countertop filters don’t remove any kind of harsh contaminants.

Here is our full comparison:

The Similarities of Undersink and Countertop Filtration

First of all, both of these systems work for filtering out your water of the most dangerous contaminants like chlorine and lead.

They are also larger than the filters used for your kitchen faucet or showerhead.

This means that they can filter a huge capacity of water and also use advanced processes to get the purest drinking water.

While they both have some of the same features, such as carbon block filters, they work differently, and in most cases, undersink filters simply do a better job.

The Differences of Under Counter and Countertop Filters

Under-Sink Water Filter Systems


  • Hidden out-of-sight design
  • Won’t take up any countertop space
  • High filtration rate


  • Requires plumbing knowledge to install
  • May require drilling into countertop if there is a second faucet
  • Larger than countertop filters

Countertop Filter Systems


  • Smaller and easy to use
  • Easier to install (there’s typically no installation or water lines involved)


  • Lower filtration scores
  • Takes up counter space
  • Frequent filter changes due to small size


With a countertop filter, it’s easy to set it up, but you may not have the counter space.

Under-counter filtration is hidden away and takes up space in your kitchen cabinet.

If you have a smaller kitchen that doesn’t have so much counter space, then you’re not going to have room for a huge countertop filter.


Since under-sink filters are installed to handle all of the water coming to your faucet, the capacity is much higher.

You won’t have to change the filter as much, and you’ll be able to get clean drinking water in a fraction of the time.

Since countertop water filters are more compact, this means that the cartridges are also very small. You won’t get the same kind of capacity and long-term use from these water filters.

Filtration Process

With in-house water pressure, an under-sink filter can use several cartridges or even reverse osmosis to create the most pure drinking water.

You won’t find many other types of processing for under-sink filtration. Most employ polypropylene and carbon filters in a multi-stage process to filter out your water, while advanced systems use reverse osmosis.

Countertop filters may use carbon filters and reverse osmosis, but you’ll also find filters that use electrolyte and gravity filtration systems.

Installation and Ease of Use

You will have to do a bit of work to install an under-sink unit. This is because you’ll have to hook it up to your water lines under the sink.

In some cases, if it has a second faucet, then you may need to drill into your countertop to install the faucet.

However, there are some modern systems that have factored in these issues and provided simple ways to use your main faucet with their filtration system.

Countertop systems are much easier to install and use. You don’t have to attach anything to a water line.

You typically only need to install the filter and pour in some water, running it several times so that the carbon particles can pass through.

Buying Guide: How to Choose an Undersink Filter

Most people want the same thing from their undersink filters.

However, what makes one filtration system better at purifying water over another?

How much budget do you have to spend on a filtration system?

These are a few features and things to keep in mind when you’re shopping for an undersink filter.

Water Waste

All filtration systems have an efficiency rating. You typically want to buy a system that has been rated highly by the FDA. In the specifications area, you may see water efficiency scores and how well it saves water.

With some water efficient filters, there is a chance that the flow rate will be poor. You should check the reviews and look at specifications to see if there is any change to flow rate with more efficiency.

Reverse osmosis systems are well known for having poor efficiency, which is why you should always look at the pure water waste ratio.

Pure Water Ratio

You will typically see this in the specifications as a “pure water ratio of 1:1,” which is very good.

This means that it is able to clean the water with the least amount of waste. In terms of efficiency, some filters don’t work as well, leading to pure water ratios of up to 5:1.

Operating Water Pressure

With any water filter, you want to get a stable feed water pressure that will allow the filtration to work at its highest capacity.

You should find the operating pressure requirements in the specifications of the system before purchasing.

You will need to check these numbers or “PSI” against your own home’s pressure. Here is a quick guide to measuring water pressure in your home.

Multi-Stage Filtration

There are 2-stage, 3-stage, 4-stage, 5-stage, and 6-stage water filtration systems on the market.

Simply because a system has more stages doesn’t make it entirely better or more valuable due to budget issues.

However, a 3-stage filtration system is pretty standard in water filtration and will remove most of the contaminants in your water supply.

Above that, especially with reverse osmosis systems, you are getting close to 100% filtered pure water.

In these stages, your water should test negative for lead, chlorine, fluoride, lead traces, heavy minerals, and petrochemicals.

At each stage of the process, your system will use a different filter. Typically, in a 3-stage filtration system, you will start out with a polypropylene filter that filters out some of the larger problems, such as chlorine and petrochemicals.

Then, there will be the first carbon block filter that blocks lead, heavy minerals, and nitrates. A final carbon filter is added for refinement and taste.

Filter Life

When it comes to filters, you want a system that is going to last for multiple years. Undersink filtration systems are known for having longer filter capacities, but it also depends on the size and type of filtration system.

You can look at the specifications to see how many filters the system uses, as well as how many gallons it is rated for.

Typically, if a system is rated for 10,000 gallons, that means it will last for one year. The best systems are able to handle 50,000 gallons, which cuts down considerably on the cost of filters.


In addition to energy efficiency certifications and FDA approval, you can check for a number of different certifications that guarantee your filter will purify your water. These water filter certifications include:


NSF Certification

This means that your water filter is built well, uses approved plastics, and uses materials that will last.

In addition, NSF checks that the label statements are 100% true and that the test results are negative for all chemicals promised to be removed in the label.

There are a few different certifications including NSF 53, NSF 58, NSF 42, and NSF 401.

WQA Certified Water Filters

You will typically see a golden seal to show that the filter has been tested and is able to remove 98% of the lead in your water.

Ease of Installation and Filter Change

Not all undersink filters need a separate faucet and some are easy to install in just minutes. However, the most difficult part of this installation is probably drilling through the cabinet or countertop.

With second faucet filtration systems, you will need to create a hole in the countertop in order to pull through the faucet.

The benefit of this is that you won’t have to buy as many filters, since you’ll still be able to use your other faucet for hot and cold water.

The easiest to install filtration systems hook up to your main faucet, but these may only hook up to your cold water line.

This means that you won’t be able to filter out water to your hot line, and you will likely use your filter more, even when you’re not in need of drinking water.

Cartridge Life

Carbon cartridges are used in every filtration system to remove bad odors and tastes, such as those from chlorine. Other cartridges are able to remove high percentages of lead.

There are a few different types of cartridges that may be used depending on the system you buy, including:

  • Reverse osmosis cartridges
  • Carbon block
  • Granular activated carbon (GAC)
  • Sediment cartridges
  • Ceramic cartridges

Most undersink systems use reverse osmosis and carbon block cartridges, which tend to last at a minimum of six months.

This also depends on how the system is installed. If you have a separate faucet installed with your filtration system, your cartridges will last longer, typically over a year or more.

Under Sink Water Filter Installation

There are a couple ways that under counter water filters may be installed, but the one common theme is that you need to know your home’s water pressure and how to connect your water lines to the system.

In cases where you are simply hooking up a new faucet for pure drinking water, you’ll place the under-sink filter below your sink and hook up the water line.

However, you probably don’t want your filtration system to sit on the floor of your cabinet, so you may need to drill and attach it to the side wall of your cabinet. This keeps it away from other chemicals under the sink.

If your system does have a second faucet, you may need to drill a hole in your countertop so that you can access the faucet. In other systems, you simply hook up the water line to your main faucet and never need to drill at all.

For those unsure if they would be able to install a system like this, here’s a quick video that shows the basic requirements for installing an under-counter water filtration system.

Maintaining Your Water Filtration System

In some advanced systems, you’ll be notified when the cartridges need to be changed.

Otherwise, you will likely have to change the cartridge once per year unless you buy a system rated for higher capacity, such as a 50,000 gallon filtration system.

Here’s a step-by-step guide to cleaning your system and changing out the cartridge:

  1. Close the shut-off valve so that your sink doesn’t have any water flowing to it.
  2. Relieve the pressure in your system by opening the faucet where the filtered water comes out.
  3. Use a wrench or manually twist off the filter housing. You should be careful to keep this upright as it is typically filled with water.
  4. Remove all of the casings and cartridges inside. You may notice some grime buildup on the O-rings or mold. Manufacturers typically recommend that you change these each year to avoid this issue. These are necessary to create a tight seal.
  5. If you notice a lot of sediment in the cartridges before throwing away, you probably need to change the filters out more frequently.
  6. Clean your filter housings with hot water and soap, using a soft-bristled brush to clean out the grooves.
  7. Replace all of the parts and push in your new cartridge once clean. Run your water for up to 5 minutes to ensure that it’s clean of carbon particles.