You are probably here because you want safe, healthy drinking water for you and your family.

Unfortunately, no tap water is safe anymore, even if you have “high quality” city or well water.

According to the Environmental Working Group’s (EWG) Tap Water Database:

  • 81% of American’s water contains contaminants linked to cancer
  • 77% of Americans are drinking hexavalent chromium (the “Erin Brockovich” chemical)
  • Water samples from all 50 states have been found to contain: arsenic, chromium-6, disinfection byproducts, lead, nitrates from fertilizers, and radiological contaminates.

Also, the EWG recommends reverse osmosis water filters as the “most effective” way to filter your water since it will remove common and dangerous contaminants such as:

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

But picking the right options for your first reverse osmosis water filter system can be overwhelming.

That’s why RO-System.org is your reliable source for the best reverse osmosis system 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 RO water system, we can help!

If you decide that a reverse osmosis water filter system is not right for you, check out the best whole house water filter reviews for some great alternatives.

Before you start looking at individual RO systems, check out 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

Our top 10 options are “point-of-use” undersink water filter systems that are installed and used at a single location, which is usually under the kitchen sink.

They include a separate faucet that is installed along side your standard faucet to produce filtered water just for drinking and cooking. With additional parts, you can also run a water line to your refrigerator, if it is has a water dispenser and/or ice maker.

Waterdrop G3 RO System
NU Aqua Platinum Series 7-Stage
Home Master TMAFC-ERP Artesian RO System
Home Master TMHP HydroPerfection RO System
NU Aqua 5 Stage Reverse Osmosis System
Our Rating
Installation
DIY Undersink
DIY Undersink
DIY Undersink
DIY Undersink
DIY Undersink
Stages
7
7
7
9
5
Output
400 GPD
100 GPD
75 GPD
75 GPD
100 GPD
Wasted Water
1 Gal : 1 Gal Filtered
2 Gal : 1 Gal Filtered
1 Gal : 1 Gal Filtered
1 Gal : 1 Gal Filtered
2 Gal : 1 Gal Filtered
Tank Size
Tankless
3.2 Gallons
3.2 Gallons
3.2 Gallons
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Free Shipping
Waterdrop G3 RO System
Model
Our Rating
Installation
DIY Undersink
Stages
7
Output
400 GPD
Wasted Water
1 Gal : 1 Gal Filtered
Tank Size
Tankless
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More/Buy
NU Aqua Platinum Series 7-Stage
Our Rating
Installation
DIY Undersink
Stages
7
Output
100 GPD
Wasted Water
2 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More/Buy
Home Master TMAFC-ERP Artesian RO System
Our Rating
Installation
DIY Undersink
Stages
7
Output
75 GPD
Wasted Water
1 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More/Buy
Home Master TMHP HydroPerfection RO System
Our Rating
Installation
DIY Undersink
Stages
9
Output
75 GPD
Wasted Water
1 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More/Buy
NU Aqua 5 Stage Reverse Osmosis System
Our Rating
Installation
DIY Undersink
Stages
5
Output
100 GPD
Wasted Water
2 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More/Buy

Continue reading for systems #6-10 below…

1. Waterdrop G3 Reverse Osmosis System

Waterdrop G3 RO System
Waterdrop G3 Reverse Osmosis System

The Waterdrop G3 RO system is a powerful new under sink reverse osmosis system that provides excellent features, a sleek compact design, and lots of clean pure water for you and your family with seven stages of filtration.

There are three big features that set the Waterdrop apart from competing systems:

Tankless design

While most undersink water filter systems rely on a pressurized storage tank to hold filtered water, the Waterdrop filters the water on demand and without a tank. This means that it will keep producing when other systems will slow down to refill the tank.

5x the daily output

With an internal pump and no storage tank, this system can produce up to 400 GPD (gallons per day) of filtered water compared to just 75 GPD from competing systems.

Incredible feedback on the quality of your water

When in use, an LED ring on the faucet glows with different colors to show you the status of the filters. At the same time, the front LCD panel on the filtration system reports both the filter status and the current TDS (total dissolved solids) level of the filtered water in real time. Any other system would need a 3rd party TDS meter to get the same information on water quality.

When you consider that the Waterdrop G3 takes up less space, produces more purified water, and gives better feedback than any other system, it should be near the top of your list!

For more details on this system, check out our full Waterdrop G3 reverse osmosis review or click the button below.

Buy or More Info

4. NU Aqua 7 Stage Reverse Osmosis System

NU Aqua 7 Stage Reverse Osmosis System
NU Aqua 7 Stage Reverse Osmosis System

The NU Aqua 7 Stage Reverse Osmosis Water Filtration System has all of the same features as many competitors but at a much better price.

In addition to having the 5 basic stages of filtration, this system also offers:

  • UV (Ultraviolet light) Filter to destroy bacteria and other mcroorganisms
  • Alkaline Filter to add beneficial minerals back to the water
  • Booster Pump to improve efficiency and decrease wastewater

The NU Aqua also has a high 100 gallon per day capacity. While most people wouldn’t filter this much water, higher capacity gives you a higher flow rate.

The other big feature is a 5 year manufacturer warranty and lifetime support. Only one other brand in our recommendations offers a 5 year warranty and it’s a great benefit.

Finally, NU Aqua provides a free digital PPM meter water tester so that you can get a quick measurement of overall water quality. This is a nice bonus to round out the package.

For more details on this system, check out our full NU Aqua Systems Reverse Osmosis Review or click the button below.

Buy or More Info

Want to keep your garden growing indoors?

2. Home Master TMAFC-ERP Artesian Reverse Osmosis System

Home Master Artesian Reverse Osmosis System
Home Master Artesian Reverse Osmosis System

The Home Master TMAFC-ERP combines the perfect balance of useful benefits, popular features, and value in one package. Because of that…

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.

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 pay for 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 production 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 straight forward 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.

Buy or More Info

3. Home Master TMHP HydroPerfection Reverse Osmosis System

Home Master HydroPerfection Reverse Osmosis Water Filter System
Home Master TMHP HydroPerfection

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, including well water.

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 click the button below.

Buy or More Info
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…

5. NU Aqua 5 Stage Reverse Osmosis System

NU Aqua 5 Stage Reverse Osmosis System
NU Aqua 5 Stage Reverse Osmosis System

NU Aqua is new to our recommendations in 2020 with their 5 stage system.

If you are looking for a really nice budget system that has everything you need without any extras at a great price, then this is the one to get.

A few things about the NU Aqua stand out and make it better than other basic 5 stage reverse osmosis systems.

First, the NU Aqua has a high 100 gallon per day capacity. While most people wouldn’t filter this much water, higher capacity gives you a higher flow rate. Despite this, the system still gets an average waste water ratio of 3 gallons wasted for every one gallon of purified water.

The other big feature is a 5 year manufacturer warranty and lifetime support. Only one other brand in our recommendations offers a 5 year warranty and it’s a great benefit.

Finally, NU Aqua provides a free digital PPM meter water tester so that you can get a quick measurement of overall water quality. This is a nice bonus to round out the package.

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 even more details on this system, check out our full review of NU Aqua Systems.

Buy or More Info

Best Reverse Osmosis Systems 6-10

iSpring RCC7AK-UV 75GPD 7-Stage Under Sink Reverse Osmosis RO Drinking Water Filtration System with Alkaline Remineralization Filter and UV Ultraviolet Filter
Home Master TMAFC-ERP Artesian RO System
APEC Water Systems ROES-PH75 Essence Series Top Tier Alkaline Mineral pH+ 75 GPD 6-Stage Certified Ultra Safe Reverse Osmosis Drinking Water Filter System
APEC Water Systems ROES-50 Essence Series Top Tier 5-Stage Certified Ultra Safe Reverse Osmosis Drinking Water Filter System
iSpring RCC7AK 6-Stage Superb Taste High Capacity Under Sink Reverse Osmosis Drinking Water Filter System with Alkaline Remineralization-Natural pH, White
Our Rating
Installation
DIY Undersink
DIY Undersink
DIY Undersink
DIY Undersink
DIY Undersink
Stages
7
7
6
5
6
Output
75 GPD
50 GPD
75 GPD
50 GPD
75 GPD
Wasted Water
3 Gal : 1 Gal Filtered
4 Gal : 1 Gal Filtered
3 Gal : 1 Gal Filtered
3 Gal : 1 Gal Filtered
3 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
3.2 Gallons
3.2 Gallons
3.2 Gallons
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Free Shipping
iSpring RCC7AK-UV 75GPD 7-Stage Under Sink Reverse Osmosis RO Drinking Water Filtration System with Alkaline Remineralization Filter and UV Ultraviolet Filter
Our Rating
Installation
DIY Undersink
Stages
7
Output
75 GPD
Wasted Water
3 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More
Home Master TMAFC-ERP Artesian RO System
Our Rating
Installation
DIY Undersink
Stages
7
Output
50 GPD
Wasted Water
4 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More
APEC Water Systems ROES-PH75 Essence Series Top Tier Alkaline Mineral pH+ 75 GPD 6-Stage Certified Ultra Safe Reverse Osmosis Drinking Water Filter System
Our Rating
Installation
DIY Undersink
Stages
6
Output
75 GPD
Wasted Water
3 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More
APEC Water Systems ROES-50 Essence Series Top Tier 5-Stage Certified Ultra Safe Reverse Osmosis Drinking Water Filter System
Our Rating
Installation
DIY Undersink
Stages
5
Output
50 GPD
Wasted Water
3 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More
iSpring RCC7AK 6-Stage Superb Taste High Capacity Under Sink Reverse Osmosis Drinking Water Filter System with Alkaline Remineralization-Natural pH, White
Our Rating
Installation
DIY Undersink
Stages
6
Output
75 GPD
Wasted Water
3 Gal : 1 Gal Filtered
Tank Size
3.2 Gallons
Permeate Pump
Remineralization
UV Light
Relative Price
Our Review
Free Shipping
Learn More
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…

6. iSpring RCC7AK-UV Reverse Osmosis System

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

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 outlet.

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 Price on Amazon

7. Home Master TMAFC Artesian Reverse Osmosis System

Home Master Artesian Reverse Osmosis System
Home Master TMAFC Artesian RO 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, which is above average.

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.

Buy or More Info

8. 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 APEC ROES-50 we recommend below, 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, compared to 50 gallons per day from the ROES-50.

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.

Check Price on Amazon

9. 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 Price on Amazon

10.iSpring RCC7AK Reverse Osmosis System

The iSpring RCC7AK is a popular and highly-rated variation of the basic iSpring RCC7.

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.

Check Price on Amazon

Best Whole House Reverse Osmosis Water Filter Systems

The under sink water filters listed above are point-of-use and will only filter water at the location they are installed.

If you decide you want the cleanest possible water everywhere in your house, or you have very high water volume needs, then a whole house reverse osmosis system could be the best option for your home or business.

The downsides of whole-house reverse osmosis are the high price to purchase and maintain as well as some wasted water. The process of reverse osmosis produces wastewater that is diverted down the drain before it is ever used. In places where water costs are high, this will add cost to owning the system.

Also, the process of reverse osmosis is not as fast as other filtration options. You can install an RO system to filter on demand, but the flow rate will be low compared to your water pressure. For optimal efficiency, your setup should include a holding tank. The RO system filters water into a holding tank as needed, and then your house draws filtered water from the tank.

The primary criteria for selecting a home system is the gallons per day (GPD) you expect to use. A good estimate of usage is 75 gallons per day (GPD) per person, so a family of four would want to look at 300+ GPD options. However, be sure to leave room for expansion or spikes of heavier than average usage. Many of these systems can be scaled up to thousands of gallons per day.

The following systems are appropriate for a home of any size, a small business that needs pure water, or light industrial/commercial filtering applications.

Also, any of these systems can be combined with a water softener and/or additional whole house water filters to handle the unique contaminants in your water.

Tier1 Everyday Series Whole House Reverse Osmosis System

Tier1 Everyday Series Whole House RO System
Tier1 Everyday Series Whole House RO System

Available in both a 350 GPD (gallon per day) and 700 GPD version, the Tier1 Everyday Series feature a 5-stage filtering process starting with a sediment and carbon pre-filter, two high capacity reverse osmosis semipermeable membranes, and a carbon filter to complete the filtering process.

The first two stages remove physical particulates such as sand, rust, silt, and soil. They also reduce the presence of chlorine taste and odor, which are a common concern in city water.

The 3rd and 4th stages contain the reverse osmosis membranes that reduce water soluble toxins such as heavy metals, organics, bacteria and captures a significant percentage of high toxic impurities, such as asbestos, hexavalent chromium, and lead. Many other contaminants are removed as well, since the RO membranes only allow molecules the size of water or smaller to pass through.

The final stage “polishes” the water to remove any remaining off-tastes or odors.

Tier1 provides plenty of support and guidance during the buying process, should you have any questions about these systems.

Tier1 Everyday Series Whole House Reverse Osmosis Systems
Tier1 Everday Series 350 GPD RO System

Tier1 Everday Series 350 GPD RO System


Tier1 Everday Series 700 GPD RO System

Tier1 Everday Series 700 GPD RO System


Tier1 Advanced Series Whole House Reverse Osmosis System

TIer1 1000GPD Advanced Series Whole House RO System
TIer1 1000GPD Advanced Series Whole House RO System

Available in both a 1000 GPD (gallon per day) and 2000 GPD version, the Tier1 Advanced Series feature the same 5-stage filtering process of the Everyday Series described above.

The major difference is that they are capable of much higher GPD processing and are appropriate for larger houses or business/industrial use with triple RO membranes.

The other upgrade in the Advanced Series is that they include a high-pressure pump and solenoid valve to ensure water flows quickly through the sediment, carbon block pre-filters, and RO membranes without losing water pressure.

Tier1 Advanced Series Whole House Reverse Osmosis Systems
Tier1 Advanced Series 1000 GPD Whole House RO System

Tier1 Advanced Series 1000 GPD Whole House RO System


Tier1 Advanced Series 2000 GPD Whole House RO System

Tier1 Advanced Series 2000 GPD Whole House RO System


FilterWater Commercial Reverse Osmosis System

FilterWater 500 GPD Whole House RO System
FilterWater 500 GPD Whole House RO System

Labeled as a “light commercial” filtration system, these option from FilterWater makes a great whole-house reverse osmosis solution for homes. They are available in versions capable of processing from 200 up to 10,000 GPD.

The 200 GPD option offers separate cartridges for sediment filtration, a carbon block for chlorine, odor and VOCs removal, a 5-stage granular activated carbon filter, and a high-flow reverse osmosis membrane.

They make it easy to upgrade to a full solution with storage tanks in several sizes and an optional upgrade kit containing a digital TDS (Total Dissolved Solids) meter and a Concentrate Recycle Valve, that recycles wastewater to achieve a higher recovery rate with less water loss.

If you qualify, FilterWater offers financing so you can spread the cost of your water filtration system out over time.

FilterWater Whole House Reverse Osmosis Systems
FilterWater 200 GPD Whole House RO System

FilterWater 200 GPD Whole House RO System


FilterWater 500 GPD Whole House RO System

FilterWater 500 GPD Whole House RO System


Whole House Reverse Osmosis Water Holding Tanks

Since the reverse osmosis process reduces water flow, it is recommended to add a holding tank to your setup. Water is filtered into the RO tank first and then is ready for you to use on-demand.

Tanks are selected and sized separately from the filtration systems based on your on-demand water needs.

Tier1 offers reverse osmosis holding tanks in 80 gallon, 300 gallon, and 500 gallon capacities.

Tier1 Reverse Osmosis Holding Tanks
Tier1 80 Gallon Pressurized RO Tank

Tier1 80 Gallon Pressurized RO Tank


Tier1 300 Gallon Atmospheric RO Tank

Tier1 300 Gallon Atmospheric RO Tank


FilterWater offers reverse osmosis holding tanks with optional booster pumps in 165 gallon, 220 gallon, and 550 gallon sizes.

FilterWater Reverse Osmosis Holding Tanks
FilterWater Pressurized RO Storage Tanks

FilterWater Pressurized RO Storage Tanks


FilterWater Atmospheric RO Storage Tanks

FilterWater Atmospheric RO Storage Tanks


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 an 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?

Only reverse osmosis systems can remove or drastically reduce all of the following harmful contaminants:

  • Aluminum
  • Ammonium
  • Arsenic 5
  • Bacteria
  • Barium
  • Cadmium
  • Calcium
  • Chloride
  • Chlorine
  • Chloramines
  • Chromate
  • Chromium
  • Copper
  • Cyanide
  • Cysts
  • Fluoride
  • Iron
  • Lead
  • Magnesium
  • Manganese
  • Mercury
  • Nitrate
  • Nitrite
  • Pesticides
  • Phosphate
  • Potassium
  • Protozoa such as Cryptosporidium and Giardia
  • Radium
  • Radon
  • Selenium
  • Silver
  • Sodium
  • Strontium
  • Sulfate
  • Sulfite
  • Turbidity
  • Viruses
  • Zinc
  • … and many more!

How Does Reverse Osmosis Work?

How Does Reverse Osmosis Systems Works
Diagram of an undersink reverse osmosis system.

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. 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.

Hard Water

Reverse osmosis does remove minerals from water but is not meant to replace a water softener if you have hard water. Water softeners work specifically to remove the “hard” minerals of calcium and magnesium from water and make it “soft.” Hard water is not unhealthy but can cause many problems for your appliances, plumbing, and for the people that bathe in it. Be sure to check out our reviews of the best water softeners to find out more.

85% of U.S. households have hard water and installing a whole house water softener will both improve the water at all points of use and protect your reverse osmosis system from dealing with hard water.

Optional Accessories

Be sure to check out our guide to the best reverse osmosis accessories for even more options. This can include refrigerator connection kits, alternative faucets and tank sizes, as well as water quality testing tools.

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 undersink reverse osmosis systems come with an Ultraviolet (UV) light, although more should include one. All of the whole house systems have a UV filter add-on.

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 but 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.

Waste Water

One of the common complaints about RO systems is that they waste a great deal of water when flushing the RO membrane. 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.

With undersink systems, the figure is more often 1-4 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.

Air Gap Faucet

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

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, but it is rare.

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

All of the top reverse osmosis systems that we have reviewed here require some degree of installation before they will operate.

They are designed to be permanently installed with connections into the cold water feed pipes and waste pipes under a sink. Installation for any of these systems is similar and can be easily carried out by anyone with basic DIY skills and tools. The only difficult part is drilling a mounting hole in the sink/counter for the filtered water faucet, if a hole does not already exist.

If you choose a whole house reverse osmosis system or prefer one of our recommended best whole house water filters, the installation is slightly more involved and may require a plumber.

However, if these systems require too much installation or don’t work for your situation, check out our reviews of the best countertop water filter systems. With three different categories to choose from, it’s possible to have filtered water anywhere!

Faucet Types

There are two types of faucets available with undersink 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 under sink 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:

  • Turn 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 5 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 below.

It may be easy to go and pickup a Costco reverse osmosis system, or another generic water filter system from Lowes or Home Depot. Unfortunately, you are very limited to the brands and features they offer and may not get a great system or even a system that other customers would rate well.

By selecting a system based on reviews and recommendations here as well as reviews from the stores selling the top rated systems, you are more likely to get something that is worth the effort and expense.

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:

Undersink RO Comparison Chart

RO System NameOur
Rating
Filtration
Stages
OutputRelative
Price
Home Master TMAFC-ERP Artesian5775 Gallons$$$
Home Master TMHP HydroPerfection5975 Gallons$$$$
Waterdrop RO57400 Gallons$$$$
iSpring RCC7AK4675 Gallons$$
APEC ROES-PH75 Alkaline Mineral pH+4675 Gallons$$
iSpring RCC7AK-UV4775 Gallons$$$
Home Master TMAFC Artesian4750 Gallons$$$
APEC ROES-50 Top Tier Essence4550 Gallons$$
iSpring RCC74575 Gallons$$
APEC RO-90 Top Tier Supreme High Flow4590 Gallons$$$

Conclusion

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.

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