RO-System.org is your reliable source for the best reverse osmosis reviews and detailed water filter information.  If you want to learn more about how reverse osmosis works, discover the right water filtration system for you, or add popular accessories to an existing reverse osmosis (RO) system, we can help!

You are probably here because you want safe, healthy drinking water for you and your family.  Reverse osmosis is the most effective way to purify your tap water, but picking the right options for your first reverse osmosis system can be a little overwhelming.   We have taken the uncertainty out of the process by researching complete reverse osmosis reviews, rating the top systems, and comparing the latest water treatment features.  

From all of the available options, we have selected the top 10 best reverse osmosis water filtration systems for your consideration. Our exclusive list scores and ranks the complete range of features that can clean any tap water, regardless of its quality or source.

Before you start looking at individual RO systems, it may be beneficial to spend a few moments looking at our Reverse Osmosis Buying Guide (below). You will learn how reverse osmosis works, the terms that you will come across in your research, and understand which features matter for your health.

Best Reverse Osmosis Systems 1-5

#1 PICK
  • Home Master
    TMAFC-ERP Artesian
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    7

  • Output

    75 GPD

    Gallons per day processing rate
  • Wasted Water

    1 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

LOADED
  • Home Master TMHP HydroPerfection
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    9

  • Output

    75 GPD

    Gallons per day processing rate
  • Wasted Water

    1 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

  • Home Master
    TMAFC Artesian
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    7

  • Output

    50 GPD

    Gallons per day processing rate
  • Wasted Water

    4 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

VALUE
  • iSpring RCC7
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    5

  • Output

    75 GPD

    Gallons per day processing rate
  • Wasted Water

    3 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

VALUE
  • APEC Top Tier
    Essence ROES-50
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    5

  • Output

    50 GPD

    Gallons per day processing rate
  • Wasted Water

    3 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

Home Master TMAFC-ERP Artesian Full Contact Undersink Reverse Osmosis Water Filter System

1. Home Master TMAFC-ERP Artesian Reverse Osmosis System

Our #1 pick for most people is the Home Master TMAFC-ERP Artesian Reverse Osmosis system. 

Home Master takes the top three spots of our reverse osmosis reviews and the TMAFC-ERP combines the perfect balance of useful benefits, popular features, and value in one package.

There are two big features that set the TMAFC-ERP apart from other mid-range options and makes it the top reverse osmosis system:

First of all, water that has been purified by reverse osmosis can have a bland taste. This is because it is slightly acidic and all of the dissolved minerals that provide flavor have been removed. After the water has been purified through the TMAFC-ERP RO membrane, it passes through a remineralization filter. This adds safe minerals back into the water and raises the pH to be more alkaline.  The result is a fresher tasting mineral water that many people prefer.

Don't forget the accessories!
Don’t forget to check out the top accessories that could help you get even more out of your RO system! Read more…

In addition, it comes standard with a permeate pump, which is a non-electric device that increases the water pressure before it enters the filters.  This reduces water waste up to 80 percent and increases water production up to 50 percent.  Both of these are important if you are on city water or care about efficiency.  Compared to the average of 2-3 gallons wasted per filtered gallon produced across our reviewed systems, the TMAFC-ERP only wastes 1 gallon.

The TMAFC-ERP has 7 stages and is rated for about 75 gallons of purified water per day.

Home Master makes top quality filters that are modular in design and easy to change without tools.  Installation of this system is very straightforward and a person with some basic DIY skills should be able to complete the install within about an hour.  It comes with both a faucet and pressurized storage tank.

Also, Home Master has the only 5-year warranty of any manufacturer in our list.

For even more details on this system, check out our full Home Master TMAFC-ERP Artesian reverse osmosis review or on Amazon below.

Check The Latest Price on Amazon!

Home Master TMHP HydroPerfection Undersink Reverse Osmosis Water Filter System

2. Home Master TMHP HydroPerfection Reverse Osmosis System

If you don’t to want waste time comparing options and just want to be sure you are covered in every situation, then the Home Master TMHP HydroPerfection is the best reverse osmosis system for you.  It comes complete with every major feature and every possible filter – 9 stages in all!  This is also our #1 pick for people with a natural drinking water source.

The Home Master TMHP includes a permeate pump, which increases the output of the system to 75 gallons per day and reduces the amount of waste water needed to flush the membrane to just 1 gallon for every gallon of purified water produced.

It has a remineralization filter that adds safe minerals back into the water and raises the pH to be more alkaline.  This creates a fresher tasting mineral water.

The system also has a UV (ultraviolet) light that will kill 99.8% of microorganisms that may contaminate your water.  Municipal water sources are usually low in microorganisms but well water and other natural sources can have higher levels.  UV filters are highly recommended in situations with natural water sources.  Keep in mind that a UV filter requires a 110V power outlet.

The TMHP is rated for about 75 gallons of purified water per day and in addition to an upgraded faucet, the system now uses a larger 3/8” diameter tubing. This larger bore tubing helps increase the flow rates and the speed at which the purified water reaches the faucet.

The modular filters (which include an iron filter) are very easy to change without tools.  Installation of this system is straightforward and a person with some basic DIY skills should be able to complete the install within about an hour.  It comes with both a faucet and pressurized storage tank.

In addition, Home Master has the only 5-year warranty of any manufacturer in our list.

For more details on this system, check out our full Home Master TMHP HydroPerfection reverse osmosis review or on Amazon below.

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Home Master TMAFC Artesian Full Contact Undersink Reverse Osmosis Water Filter System

3. Home Master TMAFC Artesian Reverse Osmosis System

The Home Master TMAFC Artesian RO system is very similar to our #1 pick, the TMAFC-ERP Artesian but does not include a permeate pump.  If you already have strong water pressure or are not concerned with higher waste water rates, then the TMAFC scores very well.

Some people find that water that has been purified by reverse osmosis can have a bland taste. This is because it is slightly acidic and all of the dissolved minerals that provide flavor have been removed. After the water has been purified through the TMAFC RO membrane, it passes through a remineralization filter. This adds safe minerals back into the water and raises the pH to be more alkaline.  The result is a fresher tasting mineral water.

The TMAFC has 7 stages and is rated for about 50 gallons of purified water per day.  Like all RO systems, the TMAFC Artesian wastes water to produce the purified end result. While the amount of waste water does vary depending on the feed water pressure, this system wastes about 4 gallons of water for every gallon of filtered water it produces.

Home Master makes top quality filters that are modular in design and easy to change without tools.  Installation of this system is very straightforward and a person with some basic DIY skills should be able to complete the install within about an hour.  It comes with both a faucet and pressurized storage tank.

Finally, Home Master has the only 5-year warranty of any manufacturer in our list.

For more details on this system, check out our full Home Master TMAFC Artesian reverse osmosis review or on Amazon below. 

Check The Latest Price on Amazon!

iSpring 5-Stage Prestige Top Purity Under Sink Reverse Osmosis Drinking Water Filter System WQA Gold Seal Certified (NSF/ANSI 58) - RCC7

4. iSpring RCC7 5-Stage Reverse Osmosis System

The iSpring RCC7 is our #1 pick for a less expensive system and is very popular with a high number of positive reviews.  This is because it is a simple and inexpensive way to get basic reverse osmosis filtration without any extra features.

Despite this, it is one of the higher capacity systems that we have reviewed since it produces 75 gallons of purified water per day through 5 stages of filtration.

The iSpring RCC7 wastes 3 gallons to produce a gallon of purified water, although this amount will vary depending on your feed water pressure. This is average compared to the other systems we recommend.

The system comes with everything that you need and is designed to be installed in about 1 hour by someone with basic DIY skills.  It comes with both a faucet and pressurized storage tank.

For more details on this system, check out our full iSpring RCC7 reverse osmosis review or on Amazon below.

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APEC Water Top Tier 5-Stage Ultra

5. APEC ROES-50 Top Tier 5-Stage Ultra Safe Reverse Osmosis System

The ROES–50 is another very popular and inexpensive under sink RO system that gets a high number of positive reviews.  This is because it is a simple way to get basic reverse osmosis filtration without any bells and whistles.

It produces purified water through 5 stages of filtration and is rated for about 50 gallons of purified water per day.

The ROES–50 does waste some water during the process but at the average rate of about 3 gallons of water to produce 1 gallon of purified water.

The system comes complete with everything you need to setup and, typically, can be installed by anyone with basic DIY skills in about 1 hour.  It comes with both a faucet and pressurized storage tank.

For more details on this system, check out our full APEC Top Tier 5-Stage Ultra Safe reverse osmosis review or on Amazon below.

Check The Latest Price on Amazon!

Best Reverse Osmosis Systems 6-10

  • iSpring RCC7AK
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    6

  • Output

    75 GPD

    Gallons per day processing rate
  • Wasted Water

    3 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

  • APEC Top Tier Alkaline Mineral pH+
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    6

  • Output

    75 GPD

    Gallons per day processing rate
  • Wasted Water

    3 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

  • APEC Top Tier Supreme High Flow RO-90
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    5

  • Output

    90 GPD

    Gallons per day processing rate
  • Wasted Water

    3 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

  • iSpring RCC7AK-UV
  • Our rating

  • Installation

    DIY Under-sink

  • Stages

    7

  • Output

    75 GPD

    Gallons per day processing rate
  • Wasted Water

    3 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    3.2 Gallons

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

COUNTER
  • APEC Portable Countertop RO-CTOP-C
  • Our rating

  • Installation

    DIY Countertop

    Requires an aerator-style faucet (see full review)
  • Stages

    4

  • Output

    90 GPD

    Gallons per day processing rate
  • Wasted Water

    2 Gallons

    Gallons wasted per one gallon filtered
  • Tank Size

    No tank

    Filtered water storage volume
  • Permeate Pump
    Increases efficiency and decreases waste without electricity
  • Remineralization
    Adds minerals for improved taste and higher pH
  • UV Light
    Kills bacteria and microorganisms
  • Relative Price

iSpring RCC7AK 6-Stage Superb Taste High Capacity Under Sink Reverse Osmosis Drinking Water Filter System with Alkaline Remineralization-Natural pH WQA Gold Seal Certified (NSF/ANSI 58)

6. iSpring RCC7AK Reverse Osmosis System

The iSpring RCC7AK is a popular and highly-rated variation of the RCC7 we recommend above.

For just a few more dollars, you get the same great system as the RCC7 with the addition of a remineralization filter.  Water that has been purified by reverse osmosis can have a bland taste because it is slightly acidic and all of the dissolved minerals that provide flavor have been removed.  The RCC7AK adds safe minerals back into the water and raises the pH to be more alkaline.  The result is a fresher tasting mineral water that many people prefer.

It is one of the higher capacity systems that we have reviewed since it produces 75 gallons of purified water per day through 6 stages of filtration.

The iSpring RCC7AK wastes 3 gallons to produce a gallon of purified water, although this amount will vary depending on your feed water pressure. This is average compared to the other systems we recommend.

The system comes with everything that you need and is designed to be installed in about 1 hour by someone with basic DIY skills.  It comes with both a faucet and pressurized storage tank.

For more details on this system, check out our full iSpring RCC7AK RO reverse osmosis review or on Amazon below. 

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APEC Water Top Tier Alkaline Mineral pH+ System7. APEC ROES-PH75 Top Tier Alkaline Mineral pH+ Reverse Osmosis System

The Top Tier Alkaline Mineral pH+ is another popular under sink reverse osmosis system from APEC that gets a high number of positive reviews.

It is only slightly more expensive than the ROES-50 we recommend above, and has two advantages:

First of all, it includes a remineralization filter.  Water that has been purified by reverse osmosis can have a bland taste because it is slightly acidic and all of the dissolved minerals that provide flavor have been removed.  The ROES-PH75 adds safe minerals back into the water and raises the pH to be more alkaline.  The result is a fresher tasting mineral water that many people prefer.

In addition, it produces a 75 gallons of purified water per day through 6 stages of filtration.

The ROES–PH75 wastes the average rate of about 3 gallons of water to produce 1 gallon of purified water.

The system comes complete with everything you need to setup and, typically, can be installed by anyone with basic DIY skills in about 1 hour.  It comes with both a faucet and pressurized storage tank.

For more details on this system, check out our full APEC Top Tier Alkaline Mineral pH+ RO reverse osmosis review or on Amazon below. 

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APEC Water Systems RO-90 Ultimate Series Top Tier Supreme Certified High Output 90 GPD Ultra Safe Reverse Osmosis Drinking Water Filter System

8. APEC RO-90 Top Tier Supreme High Flow Reverse Osmosis System

The RO-90 Top Tier Supreme High Flow is another popular under sink RO system from APEC that gets a high number of positive reviews.

It is nearly identical to the ROES-50 we recommend above, but with one major difference: it is rated for 90 gallons per day.  90 GPD is the highest of any under-sink system on our charts and is an important feature if you use large amounts of filtered water for cooking, coffee, tea, ice, or an aquarium.

It has 5 stages of filtration and wastes the average rate of about 3 gallons of water to produce 1 gallon of purified water.

The system comes complete with everything you need to setup and, typically, can be installed by anyone with basic DIY skills in about 1 hour.  It comes with both a faucet and pressurized storage tank.

For more details on this system, check out our full APEC RO-90 Top Tier Supreme High Flow reverse osmosis review or on Amazon below. 

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iSpring RCC7AK-UV Deluxe Under Sink 7-Stage Reverse Osmosis Drinking Water Filtration System with Alkaline Remineralization and UV Sterilizer-WQA Gold Seal Certified

9. iSpring RCC7AK-UV Reverse Osmosis System

The iSpring RCC7AK-UV is a popular and highly-rated variation of the RCC7AK we recommend above.

You get the same great system as the RCC7AK with the addition of an Ultraviolet (UV light) filter.  UV light sterilizes the water and kills the small percentage of viruses, bacteria, and other microorganisms that could potentially remain in the water after the RO process. Most municipal water systems treat for microorganisms but well water and other natural sources can contain higher levels.  Keep in mind that a UV filter requires a 110V power plug.

It is one of the higher capacity systems that we have reviewed since it produces 75 gallons of purified water per day through 7 stages of filtration.

The iSpring RCC7AK-UV wastes 3 gallons to produce a gallon of purified water, although this amount will vary depending on your feed water pressure. This is average compared to the other systems we recommend.

The system comes with everything that you need and is designed to be installed in about 1 hour by someone with basic DIY skills.  It comes with both a faucet and pressurized storage tank.

For more details on this system, check out our full iSpring RCC7AK-UV RO reverse osmosis review or on Amazon below. 

Check The Latest Price on Amazon!

APEC Portable Countertop Reverse Osmosis Water Filter System With Case, Installation-Free, Fits Most STANDARD FAUCET (RO-CTOP-C)

10. APEC RO-CTOP-C Portable Countertop Reverse Osmosis System

The APEC RO-CTOP-C Portable Countertop reverse osmosis system allows you to enjoy reverse osmosis filtered water when the installation of an under-sink system is not practical, allowed, or when you are in a temporary location. The system is advertised as being “installation free” since all that is needed to get this system up and running is to attach it to a standard faucet in place of the aerator (sprayer, pull-out, or designer faucets won’t work).  Once connected, the entire unit will sit on the counter next to the sink.

The faucet adapter has a clever design that allows you to switch between sending water to the RO system or normally through the faucet.  It also contains the waster water tube, so that waste water can flow down the sink drain.

Although this is a small system in terms of size (16 inch x 6.5 inch x 6.5 inch) and weight (only 7 lbs.) it can produce up to 90 gallons per day through 4 stages of filtration. This output is highly dependent on the temperature and pressure of the feed water but matches the highest output under-sink system in our reviews.

Not only does this system have a surprisingly large output, it is also highly efficient. For every gallon of filtered water produced, only 2 gallons are wasted for flushing the RO membrane.  This is lower than the average of 3 gallons wasted with other systems.

One drawback with the APEC RO-CTOP-C system is that it does not have a storage tank that will provide a reservoir of filtered water.  If the source water pressure or the temperature of the water is low, it can take a long time to fill a container with purified water.  High water pressure will definitely benefit this system.

Despite the limitations, many people give the RO-CTOP-C high ratings for working well in their apartment, hotel room, RV and other places where an under-sink system is not possible.

For more details on this system, check out our full APEC RO-CTOP-C Portable Countertop reverse osmosis review or on Amazon below. 

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Reverse Osmosis System Buying Guide

What is Reverse Osmosis?

Reverse Osmosis (also referred to as “RO”) is a process where you remove impurities from water by pushing it through a semi-permeable membrane (filter).  It is the opposite of osmosis, which is one of the most important processes in nature.  In osmosis, water that is more pure naturally flows towards water that is less pure even it if has to pass through a membrane.  Reverse osmosis uses pressure to force less pure water through a membrane that blocks impurities so that you end up with very pure water on the other side.

Here is informational resource that explains reverse osmosis in greater detail and the US Centers for Disease Control and Prevention (CDC) has prepared a fact sheet about the effectiveness of different systems for purifying water.

What Do Reverse Osmosis Systems Remove?

Simple carbon water filters will remove chlorine and some organic compounds, but only reverse osmosis systems can remove or drastically reduce all of the following harmful contaminants:

  • Lead
  • Arsenic
  • Copper
  • Nitrates
  • Nitrites
  • Chromium
  • Selenium
  • Fluoride
  • Sodium
  • Cadmium
  • Phosphate
  • Radium
  • Chlorine
  • Barium
  • Bacteria
  • Cysts
  • Viruses
  • … and many more!

How Does Reverse Osmosis Work?

Although all the systems that we have reviewed are referred to as “reverse osmosis systems,” the RO filter is only one stage of the system. The RO membrane is just a very fine filter. The actual setup varies slightly from system to system and between manufacturers but the layout is basically the same as shown in the image below. How Does Reverse Osmosis Systems Work?

Water passes through one or more pre-filters (1) that remove large particles, then through the RO filter (2), which removes almost all other smaller particles.  Finally, it will pass through one or more post-filters (3 and 4) that remove off-tastes or gasses that affect the odor of the water.

While some systems will have additional components such as UV lights, permeate pumps to increase the pressure of the in-flowing water, and remineralization functions, the main process does not vary much.

Pre-Membrane Filters

In normal drinking water, there are materials that, although invisible to the naked eye, are large enough to damage the RO membrane. Typically, this filter (or filters) will remove all solids such as rust and sand, chlorine, etc. with a 5-micron filter.

RO Membrane

The RO membrane is an ultra-fine filter that removes everything larger than 0.001 microns. This means that virtually the only thing that can pass through the membrane is pure water. It can remove as much as 98% of dissolved solids from the water. With the pores of this membrane being so fine, it is understandable to see why the water pressure would affect how quickly the water could pass through.  Higher pressure is ideal.

Final Filter

Most systems pass through an additional carbon filter at the final stage to remove any lingering tastes and odors from the water. The purified water is then delivered to a storage tank until required.

Optional Accessories

Be sure to check out our guide to the best reverse osmosis accessories for even more options.

Remineralization

Standard on some systems or available as an optional extra, a remineralization stage adds beneficial minerals such as calcium, magnesium, and sometimes potassium back to the water. Not only does this enhance the taste of the water but it also raises its pH value by making it less acidic and more alkaline.

Permeate Pump

If you have low water pressure or even just want to increase the output of your RO filter system and waste less water, you should add a pump. It is possible to buy an electric pump but a permeate pump is recommended and is included as standard on some of our recommended systems, such the Home Master TMHP.

A permeate pump is a clever non-electric device that circulates the water to increase the pressure entering the system. Not only does this improve the output of the system by 50% it also greatly reduces the water needed to flush the membrane. Instead of using 4 gallons of wastewater to produce a gallon of filtered water, systems with a permeate pump waste 1 gallon to produce a gallon of purified water.  You can add a permeate pump to any system after installation.

UV Light

A few of our top reverse osmosis systems come with an Ultraviolet (UV) light, although more should include one. The purpose of the UV light is to kill 99.9% of all microorganisms that may be in the water including bacteria and viruses.  The RO filter often blocks most microorganisms before they can reach the UV filter, but you want to be sure if you have a questionable water source.

Municipal (city) water is often treated to kill microorganisms already although old or dirty pipes can still re-introduce more.  Well water and other natural sources can contain a much higher level of microorganisms and a UV filter is recommended if your water could be contaminated.  Testing your water is the best way to know for sure and you can add a UV light to any system after installation.

Reverse Osmosis Terms

When learning about reverse osmosis filtration systems, there are various terms that manufacturers use that may be new to you. Here are a few of the more common terms and what they may mean.

Stages

Every RO system has a distinct number of stages that water will pass through.  Each stage performs a different function to either filter or process the water in some way.  The number of stages is not the best way to compare how good systems are and more stages usually means more is done to purify the water.

Storage Tank

All of our top reverse osmosis systems that install under the sink come with a pressurized storage tank that will hold the finished purified water.  By pre-filtering enough water to fill the tank, the system ensures that you will get a quick response from your filtered water faucet.  Without the storage tank, you can only take filtered water as fast as the system can produce it in real time.  You can replace the standard tank with a larger one if you often need more water on demand.

Water Output

A measure of how much water a system can typically process in a day.

All RO system that we have reviewed use the same standard test for documenting their gallons per day (GPD) output figures. These tests are based on the water coming in at 77 degrees Fahrenheit (25 Celsius) and with a water pressure of 60 psi. The truth is that in real life installations, very few places have these ideal conditions. This means that quite often the output from a RO system is less (in some cases considerably less) than suggested in the datasheet. It is quite complicated to calculate the exact figures that you can expect to get from any system since lower pressure, lower temperature, and high TDS levels also lead to a reduction in output.

If your system suffers from the low output, you can probably blame lower water pressure and increase it by adding a pump to the feed water side. A permeate pump can increase output by 50% per day. Additionally, if your water supply is delivered at a very low temperature, introducing some coiled water pipe onto the feed side of the filters will allow the water to warm up before it enters the RO membrane.

Wasted Water

One of the common complaints about RO systems is that they waste a great deal of water when flushing the RO membrane. Often figures of 20 gallons wasted for every gallon of water produced are cited. These figures are misleading since they often refer to industrial-sized RO systems.

In domestic settings, the figure is more often 3-4 gallons of water being wasted to produce a gallon of filtered water. The amount of water used is highly dependent on the pressure of the inflowing water – higher pressure means less water is needed to flush the membrane.

The average across the systems we reviewed is about 3 gallons wasted per 1 gallon filtered.  A permeate pump reduces the waste water to 1 gallon for every gallon of filtered water produced.

If waste water is a concern, look for a system with a lower waste to filtered water ratio.  If you want to reclaim the “wasted” water, the waste pipe from the system can be fed into the normal cold faucet or even diverted for watering the garden.

pH / Acidic / Alkaline

The pH refers to how acidic (low pH) or alkaline (high pH) the water is.

The RO systems that we have reviewed accept a wide range of pH values in the feed water. Manufacturers that comply with EPA Secondary Drinking Water Standards will accept water that has a pH value of between 6.5 and 8.5. Water that passes through RO systems tends to have the pH value lowered when the healthy minerals are filtered out with everything else. This lower pH makes the water slightly more acidic, which can taste bland to some people. 

If this is a problem for you, you may want to look at systems that remineralize the water. A remineralization stage increases the pH value to a level closer to neutral and creates a taste that is similar to bottled mineral water.

The scale of pH values

TDS

TDS stands for total dissolved solids. Total dissolved solids usually include inorganic salts such as calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulfates, along with some small volumes of organic matter that are dissolved in water. The EPA sets a maximum TDS level of 500mg/L in drinking water is its Secondary Drinking Water Standards.

There are two ways that the total dissolved solids can be measured.  The first way is in a lab under stringent controlled conditions, which is expensive and time consuming. The second is by measuring electrical conductivity. Although this method is not as accurate as the lab test, the results gained by a fairly inexpensive meter are within 10% of the lab results. An RO system that is functioning well should reduce TDS in water by about 90% – but this is variable.

The best way to know if the filters in your systems are due for replacement is to measure both the pre-filtered and post-filtered water to compare the TDS values.
Air Gap Faucet

Air Gap Faucet

What is an air gap faucet? The air gap provides a siphon break for under sink RO systems. This means that if the sink should get backed up, there is no way that the dirty water can be siphoned back into your RO system. In some localities, it is part of the plumbing code that all RO systems should have an air gap faucet.

A few RO systems come with an air gap faucet, although most offer only a non-air gap faucet.  You can always add an air gap faucet to any system if you prefer or local plumbing code requires it.

While there are advantages to air gap faucets, a standard faucet is usually preferred. This is because air gap faucets are more complicated to install and usually need a larger, non-standard counter hole. Air gap faucets need three pipes to connect instead of just one and, in some cases, air gap faucets can be noisy.

Installation and Maintenance of RO Systems

Installation

All of the top reverse osmosis systems that we have reviewed (apart from the APEC Water Countertop system) require some degree of installation before they will operate. The APEC system is, as the name implies, sits on your counter top and attaches to your water faucet. It is ideal for temporary installations, for taking on holidays, or using in an RV.

The remaining systems we reviewed are designed to be permanently installed with connections into the cold water feed pipes and waste pipes under the sink. Installation for any of these systems is similar and can be easily carried out by anyone with basic DIY skills. The only difficulty that may be encountered is drilling a mounting hole in the sink/counter for the filtered water faucet.  

Faucet Types

There are two types of faucets available with RO systems: a standard faucet and an air gap faucet. Note, in some municipalities, it is mandatory to install an air gap faucet with an RO system, although this is widely ignored. Some sinks will have covered hole, spray hose opening, or integrated soap dispenser that can be used for your RO faucet.

A standard RO faucet usually requires a ½” to 5/8” hole. The air gap faucet, however, usually requires a 1 ½” opening and this can be beyond the scope of DIY skills, especially if a hole has to be drilled through the counter top. This requirement may affect your choice of RO system. Once the hole for the faucet has been solved, the reaming installation is very straightforward.

Installation Process

The top reverse osmosis systems that we recommend use press fit quick connectors for the water tubes, which provides a good joint without the need for any special tools or knowledge.

Although there are slight differences from system to system, installation is generally as follows:

  • Reverse osmosis installation diagramTurn off and disconnect the cold water feed pipe from the wall to the faucet.
  • Attach the supplied ‘T’ connector to the cold water feed outlet.
  • Reconnect the cold water feed to the ‘T’ connector (and if necessary, the push fit connector – in some cases, it may already be attached).
  • Drill a hole in the waste pipe for the filter waste connector. In our experience, we found that having the drain connector on a horizontal section of waste pipe reduced the noise when the system is flushing.
  • Using the drill bit as a guide, attach the RO drain connector to the drain pipe.
  • Attach the filter package to the side wall of the cupboard or back wall. Make sure that the is enough room in all directions to remove the filters and perform maintenance.  Some systems required a large, plastic wrench to loosen filter housings.
  • Place the reservoir tank on the base of the cupboard.
  • Install the filter faucet on the top of the sink.
  • Attach all of the water tubes. In most cases, the pipes are color-coded to ensure that the correct connections are made.
  • If a UV light system is present in the system, plug it into the electrical outlet.  You may need an electrician if you don’t already have power available.
  • Turn the water on and check for leaks.
  • Fill and empty the reservoir 3 to 4 times (the exact amount of times depends on the individual system).

The system is now producing filtered water.

After initial installation, it is worth checking the system every day or so for leaks. If the system remains leak free for a while, then check every month to make sure that no leaks occur.

Maintenance

All RO systems will, from time to time, need periodic maintenance and the intervals are dependent on the type of system that you have and on the quality of the water that enters the filters.

Pre and post filters will need replacing every 6-12 months or by your usage volume.  Manufacturers have recommended schedules but the best way to know for sure is to test the water before and after it is processed by your system.  You can do this yourself with a simple TDS meter.

All RO membranes have a life span of between 1 and 3 years. Again, the better the quality of the feed water the longer the membrane will last. One area that will help extend the life to the membrane is to always change the pre-filters membranes when needed.

The process varies by manufacturer although most systems have easy to change filters. In some cases, all that is needed is to lift the filter slightly out at the base, press a button on the holder and the filter comes away. Other filters pull out and the replacement just pushes in. Finally, there are the types of filters that are contained in housings.  These housings are unscrewed so that the filter cartridge can be replaced and then the housing is screwed back into place.

Apart from spending a few minutes every few months replacing old filters, the rest of the system is maintenance free.

Top RO Brands

In our review of the best reverse osmosis systems, we have included several of the major manufacturers.

Home Master

Home Master has been producing RO systems since 2002, originally under the ‘Tap Master” brand. In 2014, it re-branded as Home Master. From the start, Home Master has used modular filters. A modular filter is where the filter and housing are all one unit and this unit is changed as one piece. Not only does this make filter changes much easier, but it is more effective at ensuring that the housing remains clean of debris that may damage the filter elements.

Many of the Home Master systems come with their “fast flow kit,” which increases the output of the system without increasing the overall size. Another innovation of Home Master is their patented “Full Contact” remineralization system. This Full Contact system treats the water after it has been purified and restores the pH value by adding minerals back into the water. Remineralization effectively gives you “mineral water” on tap.

Home Master also gets high marks in our ratings for having the longest warranty of any manufacturer at 5 years.  Others brands only offer 1-3 years!

Our current Home Master recommendations include:

APEC Water

APEC, which has been producing RO systems since the late 1990s, stands for Advanced Purification Engineering Corp. and is one of the few RO manufacturers that still produces its membranes and primary filters in the USA. Every RO system that is produced in the California APEC manufacturing facility is thoroughly tested before shipping. APEC RO Systems are highly popular and are among the bestselling and highly regarded systems available.

One system that does deserve special mention is the RO–CTOP-C system. It is small, light, and does not require a permanent installation. This makes it ideal for situations where an under-sink system is not needed or allowed, such as in a rental house or an RV. Despite its small size, this system can still produce up to 90 gallons per day of purified filtered water.

APEC also donates systems to those in need as part of their Free Drinking Water charity program.

Our current APEC recommendations include:

iSpring

iSpring is a family owned company out of Alpharetta, Georgia that provides some of the best value with their under sink RO systems. iSpring also has one of the highest customer satisfaction ratings in the RO market.

Our current iSpring recommendations include:

Best Reverse Osmosis Filter Systems Comparison

RO System NameOur
Rating
Filtration
Stages
OutputRelative
Price
RO System NameOur RatingStagesOutputPrice
Home Master TMAFC-ERP Artesian5775 Gallons$$$
Home Master TMHP HydroPerfection5975 Gallons$$$$
Home Master TMAFC Artesian5750 Gallons$$$
iSpring RCC74575 Gallons$$
APEC ROES-50 Top Tier Essence4450 Gallons$$
iSpring RCC7AK4675 Gallons$$
APEC ROES-PH75 Alkaline Mineral pH+4675 Gallons$$
APEC RO-90 Top Tier Supreme High Flow4590 Gallons$$$
iSpring RCC7AK-UV4775 Gallons$$$
APEC RO-CTOP-C Portable Countertop3490 Gallons$$$

Wrap Up

We have covered a wide range of Reverse osmosis system reviews and hope that our many hours of research, exclusive ranking algorithm, and detailed comparisons have helped you to find the best reverse osmosis system for your needs.

If you are still unsure, please feel free to contact us and let us know what other questions you have.

Finally, you can learn more about RO-System.org or read our in-depth reviews of the top systems and accessories.