Drinking clean and pure water is one of the most important parts of living a healthy and well balanced life. Unfortunately, finding the best water filtration system is often difficult.

This guide will focus on helping you choose the best under sink water filter. Now, under sink filters are great because they do not take up any counter space. This guide will go over the water filters for your home and give you tips on what to look for in a filter.

We’ll also show you a few videos on how to setup these filters in your home.

Under Sink Filter Comparison Chart

 APEC 6-Stage RO SystemAPEC 5-Stage RO FilterSpring CU-A4 4-StageAPEC WFS-1000Culligan US-EZ Under Sink Water Filter
APEC Top Tier Alkaline Mineral pH+ 6-Stage RO SystemAPEC 5-Stage Reverse Osmosis Drinking SystemiSpring CU-A4 4-Stage Water FilterCulligan US-EZ Under Sink Water Filter
Filter Life10,000 gallons10,000 gallons7,500 gallons5,000 gallons1,000 gallons or 1 year
Filtration Stages6 stages5 stages4 stages3 stages1 stage
Warranty2 year - Manufacturer2 Year - Manufacturer1 Year Warranty1 Year Warranty2 Year Warranty
Reverse Osmosis
PriceView on Amazon!View on Amazon!View on Amazon!View on Amazon!View on Amazon!

Our Pick: APEC Ulitmate RO-PH90

APEC Top Tier Alkaline Mineral pH+ 6-Stage RO System

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The APEC Ultimate RO-PH90 system has everything that you could ever want in a filtration system… and then some more. It has six filtration stages, which results in some of the cleanest water that you will ever find in the world. This really is a high performing water system to treat your tap water.

Now, if that was not enough for you, then this system will add magnesium and calcium to your water. No need to worry about that though. Those are two essential minerals for you. They are the only two good additives that you find in tap water.

The filter has a 10,000 gallon life, so you won’t need to change out the filter that frequently. On top of that, these filters are some of the highest quality filters on the market.

Finally, this system also adjusts the pH level of the water, which creates alkaline water.

One of the big worries about these systems is that homeowners cannot install them without a professional. Fortunately, the APEC device is extremely simple to install. You do not need to call a plumber to install this filter. However, we still recommend doing so as that can save you a decent amount of money and future problems.

Simply put, this is the best filtration device available on the market today and it comes at a reasonable price considering the amount of filtration that you receive. For those of you looking to provide the absolute best drinking water to your family, then this solution will work well. Even a single person can use it if they drink a healthy amount of water each day.

Warranty: 1 year limited warranty. Register the product when you purchase it.

Contaminants Removed: Everything because it is a RO system. Arsenic, barium, Chromium, copper, fluoride, lead, selenium, chlorine, bacteria, and protozoans.

Filter Life: 12 months

Feed Water Pressure: 40-85 psi

Certification: Water Quality Association (WQA)



  • Reverse osmosis filtration is the best most effective filtration method.
  • This unit also adjusts the pH level to about 8.
  • Adds calcium and magnesium to the water. This keeps your bones healthy.
  • Made in the USA.


  • Most expensive unit, but still great value for all the features.
  • It takes up a lot of under sink space

APEC Essence ROES-50 (Reverse Osmosis system)

APEC 5-Stage Reverse Osmosis Drinking System

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This unit is actually the best selling water filtration device on Amazon. It got to that position with good reason too. This is one awesome reverse osmosis unit that removes 99.9% of contaminants. Yet it still comes in at a very affordable price point. It even has a 2 year warranty as well. You just need to register for the warranty when you purchase the product on Amazon.

The only real difference between this unit and the APEC Ultimate RO-PH90 listed above is that this unit does not balance the pH level. This could be problematic in an area with acidic water or if you need alkaline water for health purposes.

APEC manufacturers all products in America, so you get a high quality product compared to some of the Chinese products.

The APEC Essence ROES-50 makes an excellent choice for those looking to save a little bit of money without sacrificing product quality. Remember, this is a reverse osmosis system, so the water quality will be some of the best in the world.

Warranty: 2 year extended (register upon purchase)

Contaminants Removed: Everything. This is a reverse osmosis system, so it removes 99% of total dissolved solids (TDS) from water.

Filter Life: Pre-filter; 6-12 months, Complete Filter: 2-4 years. Replace the O-rings every year.

Feed Water Pressure: 14 psi – 50 psi. This depends onhow full the tank is. The more full it is, then the more PSI you can deliver.



  • Reverse Osmosis filtration removes 1000s of different contaminants from the water
  • Quick connect fittings do not require a leak detector. These things just don’t leak water.
  • 2 year extended warranty. Register when purchasing the product.
  • Long lasting filters that are easy to clean.


  • Reverse osmosis filtration uses a lot of water.

Best Water Filter for an RV: iSpring CU-A4 4-Stage Compact

iSpring CU-A4 4-Stage Water Filter

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Do you want a filtration unit that can fit in your RV?

The iSpring CU-A4 might be the system for you. This filter actually uses 4 filters instead of the usual 5 or more. Don’t let that fool you though. It can still filter water really well without wasting it.

It also doesn’t need a storage tank like the reverse osmosis system. This saves space underneath your sink, so you can store whatever it is that we store under the sink.

No, seriously. What do you store underneath the sink?

Anyway, this filter works great. It also doesn’t require any remineralization either, which is great. You get to keep the calcium and magnesium in the water.

Warranty: 1 year limited + lifetime phone support.

Contaminants Removed: Organics and lead.

Filter Life: 6-12 months

Feed Water Pressure: 40 psi

Certification: NSF/ANSI



  • Removes chlorine, lead, arsenic, and other nasty stuff like that
  • Small and compact. You can even use this in an RV.
  • 1 year limited warranty and lifetime technical support.
  • Easy to install and easy to change the filters.


  • Does not remove total dissolved solids (TDS).

3 Stage Filter: APEC WFS-1000 Super Capacity 3 Stage Water Filter

APEC WFS-1000 Super Capacity 3 Stage Water Filter

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Do you already have clean tap water?

This is the filter for you if that’s the case. It’s only a 3 stage water filter. This means that it only removes the tastes and odors from the water.

This is a system for homeowners that live in an area with clean tap water that just does not taste great… most of the United States.

It works great in those scenarios. It removes a lot of the taste and smell of dirty tap water.

APEC makes all their filters in the USA. This one is American made as well. They also have their standard 1 year warranty along with a lifetime support line to their water filter experts.

Warranty: 1 year limited + phone support.

Contaminants Removed: Chemicals, smell, and taste.

Filter Life: 12+ months.

Feed Water Pressure: 20-85 psi



  • Budget friendly.
  • Good warranty program.
  • Made in America.
  • Makes your water smell and taste good.


  • Does not remove many contaminants

Budget Friendly: Culligan US-EZ Under Sink Water Filter

Culligan US-EZ Under Sink Water Filter

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This choice is the best one for those of you looking for the best budget choice. It’s quite similar to the APEC system. It only removes taste and smell, which is fine if you are not concerned about the contaminants in the water.

The Culligan also has the benefit of being extremely small, so you can fit a lot of items underneath your sink. It has a decent filter life of 3,000 gallons or one year. So you do not really have to worry about changing the filter out for a year. Unless your household drinks 9 gallons of water per day.

Warranty: 2 year limited

Contaminants Removed: Particulates and chlorine.

Filter Life: 3000 gallons or 6 months.

Feed Water Pressure: 60psi

Certification: Water Quality Association (WQA)



  • Affordable
  • Makes water taste better
  • Small and light


  • Does not remove dangerous contaminants

Under Sink Water Filtration System Buying Guide

An under sink water filter attaches to your sink. Their primary use is for providing cooking water and drinking water. Now, if you already have a whole house water filtration system, then you will probably not need an under sink one as well.

Honestly, you should not need any other type of system. However, a countertop water system works well in that scenario.

Benefits of an Under Sink Water Filter

These systems have a two major advantages of other types of filtration devices.

  • Save countertop space – Counter top space is limited and highly valuable. Think of the last time you thought to yourself, “I wish I had more space under my sink.” You’ve probably never though that. You probably do wish you had more countertop space. If not, then you probably do not want to clutter up your counter with more appliances.
  • Removes All Types of Contaminants – Gone are the days of when these systems only used an activated carbon filter, which only removes chlorine and some sediment. These systems now have all different types of filtration systems packed into them. This makes them great for any of your filtration needs.

Things to Consider Before Purchasing an Under Sink Water Filter

These systems are not particularly complicated. However, there are a few things to consider beforre purchasing a filter. These are the following considerations to take into account:

What is your why?

The most important question is why do you want a water filter. If it is just because your water tastes bad, then some of the budget options will make more sense than a reverse osmosis system.

If you are concerned about the fluoride, arsenic, lead, and other nasty metals in your water (which you should be), then an RO system is your best choice. Just remember that RO systems use a lot of water in the filtration process.

Filter Life

This is always an important consideration to make before purchasing a water filter. It is especially important with an under the sink filter. You cannot simply replace the filter like you could with a water pitcher filter.

You often have to get down on the ground and unscrew the filter and replace. This can be easy with some of the filters listed. However, it still takes time and is always going to be annoying.

The Number of Filter Stages

This is an important factor if you are concerned with the amount of total dissolved solids (TDS) in your water. More filter stages means less TDS in your water.

However, more filter stages will also increase the amount of filter changes that you will have to do. You will also have more points of failure for a potential leak. Everything here is a potential tradeoff.

Size of the System

Another important consideration is the size of the system. More stages means more size. A reverse osmosis system will be the biggest system because of its storage tank for the water.

A bigger system is necessary for a bigger household or if you want the purest water possible. Again, this is a tradeoff that you must carefully consider before purchasing a system.

The Faucet

These units come in two different varieties. Each has their own advantages and disadvantages.

  • Separate faucetis the first variety. As the name implies, these have a separate faucet. The main advantage of these units is that the water filter lasts much longer because it doesn’t filter all the water. I mean, do you really need to filter the water you use to do dishes. The disadvantage is that you have to add, or use, a hole in your sink. You may also forget to use it.
  • Simple Undersink Filter – This works by having all the water flow through the filter. There is no breakaway filter on this unit. These types are much less common for the simple reason that most homeowners do not have a need to use filtered water for everything in their sink (doing dishes). The main advantage of these is that you will never forget to filter your water. Of course, you will have to change your filter more frequently.

Installing an Under Sink Water Filter

installation instructions

Installing these things is not too difficult. I mean, it’s hard since you have to drill through your sink (or use a hole already in your sink!). It’s just not something that you necessarily need to call a plumber about. The hardest part is that you have to crawl under the small space under your sink to install it. Not very fun.

Tools Required:

  • Wrench
  • Vise Grip
  • Teflon tape
  • Plumber’s putty


  • Disconnect the water connection from the water line to the sink.
  • Wrap the T-connector with teflon tape to waterproof the connection
  • Add the T-connector to the water line. Use a vise grip to really tighter it. Just don’t over tighten or cross-thread it.
  • Connect the rubber pipe to the T-connector. This rubber pipe then attaches to the filter.
  • Remove the soap dispenser from the sink (or drill a hole in the sink).
  • Put plumber’s putty underneath the faucet.
  • Attach the faucet to the sink.
  • Screw it tight, but not too tight.
  • Attach the tubing to the faucet.
  • Finished 🙂

Maintenance: Under Sink Water Filtration System

When should I change my filter?

This just depends on the type of filter that you have and the filter life of it. One that has a 3000 gallon capacity will obviously last much longer than one that has a 500 gallon capacity. This also depends on how much water that you use.

A bigger family means more water, which means a shorter filter life. Just take a look at the manufacturer’s recommendations to get a good general idea of how frequently you need to change the filter.

How to replace Under Sink Water Filtration Cartridges

This step is much easier than the installation. Most people should be able to do this themselves.

Tools Required:

  • Cartridge housing removal tool
  • 5 gallon bucket

Replacement Instructions:

  • Turn off the water.
  • Open the faucet to drain all the water from the filter.
  • Place the 5 gallon bucket under the filter (optional)
  • Use the cartridge housing removal tool to take off the cartridge housing.
  • Remove the old filter.
  • Use warm water and soap to clean out the housing. This has a tendency to get grimy.
  • Drop a new filter in.
  • Reattach the housing. Make sure to hand tighten. You can easily tighten too much with the tightening tool.

Final Thoughts

All in all, you can’t go wrong with an under sink water filter. The extra faucet will serve as a great reminder to constantly drink more water. You also save valuable countertop space with an under the sink solution.

Finally, you can have the best water filtration system, reverse osmosis, right under your sink to deliver you fresh and clean drinking water.