Best Reverse Osmosis Systems

RO systems, as they are commonly called, can eliminate up to 99% of all total dissolved solids in your drinking water. They combine sediment filters and carbon filters for maximum filtration efficiency. Reverse osmosis water filtration systems perform the most extensive water filtration processes on contaminated water, leaving you with nothing but fresh drinking water!

Let’s face it: with our environment deteriorating constantly, the integrity of our tap water is questionable. You’d be right to think that most of it is compromised. Sometimes the water comes with lots of chemical and minerals (such as excessive chlorine), posing more harm to your body. The lead that coats most water pipes makes it even worse. After prolonged use of the water, the pollutants can take a toll on your health and that of your loved ones.

If you are worried about the level of dangerous contaminants in your water, then this system could be all you needto put your mind at ease. The list below has the best reverse osmosis systems on the market today, so read on to find out the perfect model for your home.

The Winner, Second Best, Editor's Choice
Home Master
Model: TMAFC Artesian
Flow Rate: 50 GDP
Filtration Stages: 7
Max Pressure (psi): 75
5 year warranty
Model: RO-90 Ultimate Series
Flow Rate: 90 GDP
Filtration Stages: 5
Maximum pressure (psi): 85
2 year warranty
Model: RCC7AK
Production Rate: 75 GDP
Filtration Stages: 6
Max Pressure (psi): 75
1 year warranty

Best RO System - Full Comparison Table
50 GPD73.2 gal.TMAFC Artesian
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75 GPD64 galApec ROES-PH75
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75 GPD63.2 galiSpring RCC7AK
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90 GPD54 galApec RO-90
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50 GPD53.2 galExpress Water RO5DX
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400 GPD3TanklessWaterdrop WD-G3-W
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100 GPD41.6 galBrondell RC100
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400 GPD3TanklessGreatwell ROG400
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25 GPD33.2 galWhirlpool WHER25
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600 GPD2TanklessWatts WP500313
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Home Master RO water filter system
Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Highly Effective Purification
  • Filter lifespan: 2000 Gallons
  • Made in the USA with 5 Year warranty


There are good reasons why the reverse osmosis water filtration system from Home Master is the most highly reviewed RO system in the marketplace. It has a perfect combination of popular features, benefits, and value, all in one neat package.

The Home Master TMAFC system features an advanced modular filter system, which encases both the system’s filters and housing into one casing, allowing you to use and replace them every year. What this does is that it prevents leakages, gives the product a long life, and it is a more hygienic approach, which is much better than separate filter canister products.

Replacing the filters is a breeze! You will not need to wrestle with your filter casings, as is the case with some other models. The replacements have push-in tubing, which makes it possible to perform a wrench free maintenance. To combat slow filtered water supply,the system comes with larger fittings and tubes that enhance water flow.

The other advantage of the TMAFC Artesian Full Contact RO system is its remineralization feature. Unlike other models that produce deionized acidic water, the Home Master TMAFC has a process that takes the water produced from the reverse osmosis membrane through a duo remineralization process. This feature places it in the same rank as the APEC ROES-PH75, iSpring RCC7AK, and the APEC RO-90.

When water is getting to the storage tank, it encounters its ‘Full Contact’ remineralization system that balances the water’s PH levels by adding calcium and magnesium minerals to it. This helps cut down storage tank degradation.

And there’s more! The model has a six-stage water filtration process that can produce 50 gallons of filtered alkaline water in a day. It might not provide lots of water for the larger homes, but this amount is ideal for your normal consumption and usage.And to make the deal even sweeter, you get a five-year limited warranty should your reverse osmosis system not meet your expectations.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Improved ALKALINITY removal
  • Trusted US brand with 20 years of history
  • High purity RO water and at 75GPD


Different from the Home Master TMAFC Artesian, which has four filtration cartridges, the APEC Top Tier Alkaline Mineral pH+ 75 GPD RO system is a six-stage model. It is also slightly cheaper than the Home Master TMAFC Artesian.  It first has a five-micron sediment pre-filter made from industry-grade polypropylene, which has a high filtration capacity and lifespan.

The second and third stages of filtration for this reverse osmosis system utilize two premium carbon block filters that filter out VOCs, chlorine tastes, and odors from your water. Its fourth filtration stage uses a TFC RO membrane, which removes up to 99% of all contaminants from water, including barium, fluoride, and lead. To eliminate odors and tastes that mix with the water during its storage phase, the APEC Top Tier Alkaline Mineral pH+ 75 uses an activated coconut shell carbon filter to refine them out in its fifth water filtration stage. The process winds up with acid water neutralization done by a food-grade calcium carbonate mineral cartridge manufactured in the USA.

The APEC ROES-PH75’s mother company, APEC, is a well-respected brand famous for long-life products and quality filters. It is also less water wasteful than the Home Master TMAFC Artesian. The system has another significant advantage over its counterpart — it can filter up to 75 gallons of water per day, which makes it much better suited for bigger households. Some users have said that the product has a rather complicated installation process, which can, fortunately, be managed as a DIY project using the easy-to-understand manual that comes with it.

It should take about an hour to get the system up and running.  Even so, it’s essential to go through the manual first and look at its color-coded diagrams, to understand the workflow and avoid frustrations. The good news is that APEC has very responsive customer support should you encounter any challenges. Many happy buyers have said that they had live customer support at hand to guide them through installation difficulties.

Similar to the Home Master TMAFC Artesian, the product’s carbon block filters will last one year before replacement. The calcite water neutralizer will need a replacement every year, while the RO membrane and post-carbon filters will last for three to five years, depending on the levels of water contamination.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Great PH Levels
  • 98% lead removal
  • Affordable Filters


Are you worried about the water wastage feature of RO filters but need one in your home? As opposed to the Home Master TMAFC, which wastes up to four gallons for each gallon of filtered water, the iSpringRCC7AK only wastes a gallon or two for every gallon of filtered water.  Amazing, right?

This system features sediment filter encased in a transparent casing to ensure that you can quickly tell when it is due for a change by only looking at it.This is a highly beneficial aspect because the filtration efficiency of a pre-filter will determine the health of your RO system. Larger water contaminants can quickly foul your RO membrane. Thus, you should keep tabs on your pre-filters to prolong your system’s life. While the price of a pre-filter replacement is quite affordable, the cost of replacing the RO membrane is higher.It is, therefore, essential for homeowners to keep watch on the level of impurities in their water, its TDS levels, or speed of purification to determine when it is time for a pre-filter change.

If the level of impurities in water is too high, your pre-filter will not last as long as its manufacturer’s instruction. A wait and see approach for all these signs could result in poorly filtered water or a damaged RO membrane. The iSpring RCC7AK see-through pre-filter, eliminates any guesswork and helps you to protect your investment and the quality of water produced.

Its other pre-filters include a carbon KDF granulated activated carbon filter and a carbon block filter for maximum filtration efficiency. The water is then forced through an RO filter, which filters all contaminants with a diameter larger than 0.001 microns. Its fifth stage of filtration utilizes another granulated activated carbon filter that gives the water a final polish before its ready for drinking. Similar to the Home Master TMAFC and the ROES PH75, the iSpring RCC7AK has a water remineralization stage, which turns acidic water into sweet and great tasting alkaline water.

iSpring RCC7AK not only has a reasonable price but also has a filtration capacity of 75 gallons per day. Thus, it’s suitable for use in both small and medium-sized households. The product,similar most reverse osmosis water filtration systems, is complicated to install. Nonetheless, you can DIY the installation with some assistance from the product’s helpful DIY video. The manufacturer’s customer support has also been lauded for their much-needed assistance during difficult installations.

The model has a less attractive one-year manufacturer guarantee, unlike the APEC ROES-PH75’s 2-year warranty. Nonetheless, it has a one-year money-back guarantee, which should give you the confidence you need to try it. Its pre-filter and alkaline water cartridges will need to be replaced every six months while the RO membrane can last up to two years.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Large super capacity filters
  • Durable
  • Price wise


The APEC RO-90 can produce over 90 gallons of water, meaning that it is perfect for larger households than the APEC ROES-PH75. It is a mid-range priced model with great features such as its six-stage water filtration system. Its water filtration process begins with a 5-micron sediment filter made from long-life polypropylene, which enhances sediment filtration as well. The water from the sediment filters is passed through two premium carbon block filters, the same as the APEC ROES-PH75. The carbon block filters eliminate VOCs, chlorine, bad tastes, and odors from drinking water.

Afterward, the water is passed through a FILMTEC TFC RO membrane that eliminates up to 99%of all lead, viruses, bacteria, radium, and fluoride in your water. High-quality granular coconut shell activated carbon filters are used in the APEC RO-90’s fifth stage of water filtration, right before the water goes through a calcite water neutralizer that renders acidic water more alkaline.

The RO system’s parts are NSF certified, and its high-quality filters will last at least one year before they require replacement. In contrast, the iSpring RCC7AK’s carbon filters will need a replacement every 3 to 6 months. The APEC RO-90 is also designed for easy installation and has quick-fit fittings that connect easily. Therefore, you do not need clips or extra locks to have it installed under your sink.

APEC has provided a comprehensive installation manual, which you should read through thoroughly before commencing installation to avoid any frustrations. On purchase, you will get a 2-year manufacturer warranty and lifetime support from the very helpful APEC customer support.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Good customer service
  • Environmentally friendly coconut carbon filters
  • Quick and easy installation


While most other reverse osmosis water filtration systems like the APEC RO-90 and the Home Master TMAFC Artesian have water remineralizers, the Express Water RO5DX does not come with one.  But it has a robust five-stage water purification process that starts with a sediment filter, followed by a carbon block filter. Its third stage of water filtration uses an activated granular carbon filter, which eliminates chemicals such as chlorine and VOCs from your water.

This stage is followed by the RO membrane, where the harder to filter water pollutants such as lead, TDS, fluoride, Chromium, and radium are eliminated. While carbon blocks are potent water filtration products, they have more significant micron ratings than an RO membrane. Although smaller micron rated contaminates will bypass a carbon filter, they will not escape a reverse osmosis membrane, which only allows particles less than 0.009 microns through. Proficient carbon filters are key to efficient water filtration in an RO system, and they preserve the system’s life too.

The Express Water RO5DX is a quality budget RO model. A compact RO system, it will fit under small to normal-sized under sink kitchen cabinets. It has double sealed filter cartridges that help to prevent cracks giving the system durability. It also has an auto shut off Leak Stop Valve that prevents damaging water leakages that always happen when you are away from home. The feature will shut off your water flow if it detects any leakage from the system.

Express Water RO5DX is also designed for easy installation and has brass adapters for fewer leakages and prolonged life. The good people at Express Water have also provided an attractive, stylish faucet that fits in with most kitchen designs. Resembling the APEC ROES-PH75, it has a wastewater to pure water ratio of 3:1, which is above average in efficiency. Another minor yet beneficial feature is its color-coded filter casings. The colors make it much easier to know which cartridge is meant for which housing during replacement. You will only need the filter wrench provided on purchase to make filter replacements. One other advantage of buying Express Water RO5DX RO systems is that you will get free replacement cartridges on purchase. Thus, you won’t need to buy a new set of pre-filters six months down the lane.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • 1: 1 Drain Ratio mean less water waste
  • Fast flow 400 GPD
  • Attractive Tankless Desing


The innovative Waterdrop RO water system has an intelligent water purification design, and it is tankless too. With Waterdrop’s RO system, you can say goodbye to unsightly tanks that also harbor germs. The tankless design makes the system much smaller than other RO models. For instance,it has a width of 5.7 inches. The Waterdrop system is much more compact than its other tankless counterpart, the Greatwell ROG400 that has a diameter of 8 inches.

In comparison, the Home Master TMAFC Artesian model has a large tank of16 inches of width. Thus, it’s much easier to store the Waterdrop RO system under your sink, because it can use almost 75% less space than conventional RO systems.

The model also has a fast 400 GDP water flow speed, faster than any other RO system on our list. You do not need to wait for slow water filtration with it. The robust internal pump produces freshwater faster, ensuring that you can have a clean, refreshing glass of water on demand. The other fantastic feature is its 0.0001μm filtration accuracy, which is more refined than most other RO models that we have on the list that have a 0.001-micron rating.

Furthermore, it has a wide range of sensors that will remind you of the filter’s life, water quality values, and TDS ratios in real-time. Its smart leakage protector will, for instance, cut off the systems power and water supply when there is an emergency, to protect your property and appliances. By using the automatic smart flushing feature, your RO system will also last longer. The product self rinses after every 2 hours of continuous filtering and will do so too if you are away from home at a reduced pace of a minute every day.

All these fantastic features come with a price, so the Waterdrop RO system is a little pricey. Having said that, if you want to buy an environmentally friendly RO system that wastes little water, the Waterdrop RO Reverse Osmosis Water Filtration System is your best bet. It has wastewater to a filtered water ratio of 1:1.

If we could sum up the Waterdrop RO system with one word, it would be beautiful. You could easily mistake it for a high-end electronic gadget if it did not have that big Waterdrop logo that has a waterdrop on it. We are not surprised that it has won a Reddot award for its discreet appearance, space-saving compact design, and elegant white casing. By merely looking at it, you will have the impression that its water is pure and fresh.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Compact Design
  • WQA Gold Certified
  • Water Saving Smart Technology


The Brondell RO Circle system is very easy on the eye. No tubes and cartridges hanging and running all over the place. Every single item is neatly packaged into an attractive black compact casing. Due to its compactness, it will fit in under most kitchen sinks since it has a width of 9.2 inches. Brondell RO Circle has a four-stage filtration process that begins with a sediment filter. Water, rid of rust, dirt, sand, and other floaties, then goes through a pre carbon filter that eliminates chemicals such as chlorine and VOCs.

The next step involves the RO membrane filter that removes most industrial chemicals, cysts, arsenic, heavy metals, bacteria fluoride, and viruses from your water. It also has a post-filtration process that utilizes a carbon block filter. This step eliminates any remnant bad taste and odors from your water. As with the Express Water RO5DX and the Waterdrop RO system, the Brondell RO Circle system does not have a remineralization filter.

It is environmentally friendly, and it does not use electricity or pumps in its filtration process. Its water filtration efficiency is impressive too, although it’s not as efficient as the Waterdrop RO system that has a waste to filtered water ratio of 1:1. Brondell’s RO system has an efficiency ratio of 2:1. One feature that makes it more water-efficient than most other RO system is it’s back pressure elimination features. It has a Smart Valve and flexible reservoir that deters an RO system from regularly topping off its reservoir, which causes water wastage.

It’s an easy to install RO system, saving not just space but time during installation. Its valves are color-coded, and it needs minimal assembly out of the box. Its filters have a twist and seal design that enhances ease of installation. There is also a comprehensive and easy to understand manual to help you out. The three Brondell RO Circle pre-filters will need to be replaced every six months, though there is a handy LED filter life indicator that will notify you when the filters are due for a change.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • True filter change indicator
  • Unique leak-free integrated water route
  • NSF/ANSI standards components


Some users have complained that the Brondell RO Circle’s box is too big for their small under-sink kitchen cabinets. If you are in that predicament, you can purchase the Greatwell ROG400, yet another compact box-shaped RO system. The ROG400is more expensive when compared to the Brondell model despite it having a more straightforward three-stage filtration system.

It is a Deutsch iF design award winner. The RO system also only utilizes premium components manufactured according to the FDA and NSF/ANSI standards to ensure water safety and optimum filtration. The product has a composite filter that helps save more than 30% of the space within its casing. The PAC composite filter is also cheaper to maintain in the long run. It can eliminate all types of sedimentation in the water, including rust, sand, odor, bad taste, and chlorine.

The composite filter is made up of duo polypropylene sediment filters combined with carbon-based filters. The water is then channeled to an RO membrane that has a high 400GDP rating. It filters water at very high speeds providing a waste to filtered water efficiency of 1.5: 1. Its membrane can last up to three years.

At the end of the filtration process, there is an activated carbon filter, which eliminates any residual odor and bad taste from your drinking water. The product has a lead free and robust 304 stainless steel inner water-dispensing valve that connects it to the faucet. This not only gives the product a longer life but also prevents any corrosion on cheaper metals or plastic valves that could re-contaminate the filtered water.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • NSF Tested and Certified
  • Extra Long Filter Life
  • Money Saving Model


The Whirlpool WHER25 RO system is a three-stage water filtration system that is affordable. It will filter out cysts,lead, viruses, bacteria, sediment, chemicals, chlorine, and dissolved solids from your water just as well as a five or six-stage system would.  All its filtration stages are NSF standards 58 and 42 certified.  NSF 42 certification proves that the RO system can eliminate chlorine and other unpleasant water pollutants that give it a bad taste or odor. NSF 58 certification, on the other hand, is awarded to RO filters only. All NSF 58 RO systems must eliminate contaminants as per EPA guidelines.

The WHER25 RO’s first stage of water filtration engages a pre-sediment filter that eliminates large particles from water. It removes up to 95.2% of chlorine odor and tastes too. The process not only improves the taste, smell, and the look of your water but also goes a long way in protecting your RO membrane.  Its second stage of filtration uses the system semi-permeable membrane to eliminate any leftover organic and dissolved solids. The step will remove up to 99.99% of cysts, 99.1% of lead, 97% of Chromium, 98.2% of arsenic, and 75.4% of nitrites. On its last stage of filtration, the Whirlpool WHER25 RO uses an activated carbon filter that eliminates any other odors and tastes from your water.

The system is easy to install and maintain. Its filters can be changed in seconds, and like the Brondell RO Circle, it has a filter life LED light indicator too. Its carbon pre and post-filters are short life filters and last six months, similar to the Express Water RO5DX’s and the Brondell RO Circle.

Flow Rate
Filtered Water Quality
Ease of Maintenance

  • Reduces chlorine taste and odor
  • Filters up to 600 gallons
  • Removes entamoeba cryptosporidium and giardia


WattsWP500313 model is the only two-stage water filtration system we have reviewed and the most affordable. The only other product that comes close to its price range is the WHER25 RO.  The Watts WP500313 is designed to filter chemicals such as chlorine and its tastes and odor from your drinking water. Its filters have robust parasitic cysts, lead, and volatile organic compounds removal capabilities. The system willeliminate amoeba, giardia, and cryptosporidium from your water.

It will also reduce the presence of chemicals and solvents such as benzene, atrazine, lindane, trihalomethanes, and xylene, amongst others. It is not a large filtration system and can filter up to 600gallons per filter. You can only access at least 3.5 gallons of filtered water from it daily. The system is designed for smaller homes and apartment use.

The product is uncomplicated and simple to install. Its first stage of filtration utilizes a five-micron sediment pre-filter to remove larger particles from water. This includes the removal of dirt, rust, soil, and silt from it. The second stage of the filtration process is a one-micron heavy-duty carbon block that removes lead, chemicals, and parasitic cysts from water.

How To Choose the Best RO system – Buying Guide


Besides the age-old advice that an apple a day keeps your doctor away, one other standard health advice is to drink a few glasses of CLEAN water every day for better health. Water is crucial to your well being, yet not so much so, if it is polluted and unsafe. Contaminated water can be very disconcerting to a homeowner than needs to keep their household safe yet supplied with adequate clean drinking water.

Water filtration technologists have turned to the proven forces of nature to help produce clean filtered water. Through the study of osmosis, water filter manufacturers have come up with highly efficient reverse osmosis water systems that can purify any water contamination.

To help you learn about factors to keep in mind as you shop for the best reverse osmosis system, we are going to look at what this system is all about and, of course, how it works.

What Is Reverse Osmosis?

So, first things first! Osmosis is one of the most vital processes that support life on earth. In plants, the process helps water to diffuse from the environment to the plant. Animals are also very dependent on osmosis. Through it, water and nutrients are adequately distributed in the body. Osmosis also aids in the excretion of waste products from metabolism.

One common factor in osmosis in both plants and animals is the use of a semi-permeable membrane. The semi-permeable membrane controls the movement of liquid solvents from areas of higher concentration to areas where there is little of the solvents. A semi-permeable membrane, therefore, acts as a screen door. It will allow some molecules or atoms to pass through it and restrain others.

Reverse osmosis, on the other hand, is the process used to eliminate a wide range of contaminants from water. The process is also often referred to as RO, and it produces the tastiest and most refreshing water there is. While in osmosis water moves from areas of low solvent concentrations to areas that have higher solvent concentration naturally, reverse osmosis needs a push. In reverse osmosis, energy is used to push water through a semi-permeable membrane to deionize it. The process allows pure water through the reverse osmosis membrane and leaves all types of solvents and contaminants behind.

The reverse osmosis filtration system and stages

Stage 1: water pre-filtration

Home reverse osmosis water filters generally filter municipal or city water. The water is usually chlorinated but still has levels of visible sedimentation. The pre-filter is meant to eliminate these sediments and reduce the amount of chlorine in the water. The other critical use of the pre-filter is the protection of the reverse osmosis membrane. The residue in the water can easily damage the pre-filter, which is very expensive to replace. Therefore, it’s very critical to pay attention to a reverse osmosis water filter systems’ pre-filter quality.

Pre-filters mostly use activated carbon filters, which are a low-cost item. Nevertheless, these cheap filters are a very vital part of the sophisticated RO system. The common industry standard is a 5-micron pre-filter, which eliminates 5-micron diameter sized contaminants or larger. Traditionally, melt brown cartridges were used as pre-filters, but today you will find sophisticated pleated media filters. Pleated media filters are engineered to enhance water filtration surface area, which increases their protective benefits for the RO system.

A well-protected RO semi-permeable membrane can last at least two years before you need to purchase a new replacement. If your chosen RO water filtration system has a poor pre-filter, it could end up fouling every six months, which will be very difficult and expensive to maintain. The optimal RO pre-filter has a 1-micron pleated filter that has a long life and filters sediments better than a melt brown filter.

Even better is a pre-filter that protects the RO system from wear and tear from biofilm growth and carbon particulates.  If you are going to install a reverse osmosis water filtration system in a hard water area, you need to consider a softener first. The build of scale in an RO system could adversely affect your sophisticated water filtration system as well.

Stage 2: The semi-permeable reverse osmosis membrane

This is the heart of your RO water filtration system. It uses a high-pressure pump to intensify pressure on unfiltered water, which forces it across the semi-permeable membrane. Once the process is done, at least 95% to 99% of dissolved pollutants, salts, and minerals are left in the reject stream. The pressure used to force the water through the system is usually dependent on the number of solvents in the water undergoing filtration. The higher the concentration of solvents in the feed water, the higher the pressure will be required to bridle the osmotic pressure. At the end of the process, deionized or demineralized water is produced for house water use, and concentrate or reject stream is left-back for disposal.

Once your feed water from the pre-filter gets into the porous membrane canister under pressure, its molecules go through the membrane leaving behind its solvents. The water left behind is either directed to the drain or recycled back through the RO system for water-saving efficiency. RO systems use a cross filtration whereby, unlike standard filtration systems water, passes through it with two outlets.

A standard filtration system collects water contaminates within its filtration media. An RO system, on the other hand, has filtered water released through one outlet and the reject stream leaving through the other. Therefore, it prevents contamination from buildup in the RO system since water will sweep away build-up from the process.

The contaminants removed from water in this stage

A reverse osmosis water filter can eliminate up to 99% and above of dissolved particles, ions, colloids, pathogens, organics, and bacteria from your drinking water. It is crucial to keep in mind that the RO system will not eliminate all viruses and bacteria from your water. If your water is heavily infested, you will need further water sterilization through UV light water sterilization. The reverse osmosis semi-permeable membrane rejects solvents in water as per their charge and size.

If a specific contaminant in your water has a molecular weight higher than 200, it will be rejected by the RO system. This is in comparison to water that has a molecular weight of 18. If the solvent also has a high molecular charge, it will not pass through the membrane. As an illustration, sodium ions have one charge since they are monovalent. They will, therefore, easily pass through an RO membrane. However, the RO system does not purify gases such as carbon dioxide because they have a low molecular weight, and they are not highly ionized.  It’s also the reason why deionized water from RO water systems has low PH levels since the carbon dioxide in it turns to carbonic acid.

Nevertheless, RO systems are perfect water filtration systems for ground, surface, and brackish water despite their level of flow. They are proficient filters of contaminants such as;

  • Arsenic
  • Lead
  • Copper
  • Flouride
  • Selenium
  • Barium
  • Radium
  • Chromium
  • Nitrates
  • Nitrites
  • Total dissolved solids
  • Cysts

Final filtration stage

The reverse osmosis water system’s post-filtration stage utilizes a carbon post filter. The most common type of carbon filter used is the activated coconut shell carbon filter, which supplies the final water purification process for your drinking water. These filters eliminate any chlorine residue or any leftover contaminants from the reverse osmosis process.

The post-filter also eliminates any bad tastes and odors leftover in your water, especially those that are impacted by the filtration system’s holding tank or hoses. The post-filter can last at least one year of use and should be changed promptly with the best-filtered water results.

Factors to consider when buying a reverse osmosis system


Before purchase, measure your under-sink space to ensure that the RO’s dimensions fit in it. If you, for instance, have compact under sink space, you might need to move your garbage disposal for the RO system. If you are going to purchase an over the counter RO model, ensure that it is not too big, cluttering your workspace. If you are not sure about the fit of your RO system, consult a professional first.

Water pressure

RO systems are designed to work with a water pressure of 60 PSI and above. This gives them a close to 97.5% rejection rate. At lower water pressure, your RO systems might waste more water or produce little poorly filtered water. If your water is from ground sources, it most probably has 30 to 50 PSI on the higher side. Thus, it might be necessary to purchase an electric pressure booster pump to heighten the feed pressure to the reverse osmosis system.


Reverse osmosis water filters remove both bad and good elements from drinking. An inbuilt remineralization feature on your RO systems will increase the level of nutritional components in your water and make it taste better too.

Type of RO system

The very first decision you will need to make your mind up about when buying a reverse osmosis system is the type of RO most suited to your water filtration needs. There are two main types of RO systems models out there. One is known as the under-counter model, while the other is the countertop model. Below is a detailed explanation of each reverse osmosis system model.

  • Countertop RO system: Like its name, the countertop RO filter is designed to work from your countertop but can also be placed on the ground. The countertop RO system is also known as a freestanding model. It’s one outstanding characteristic is its compact nature, that ensures that it uses minimal space on your kitchen counter. If you live in a rented apartment and are not allowed to make permanent changes to your kitchen’s plumbing, then the freestanding RO model is the best for you. It is designed to ensure ease of installation, so you do not have to call in a plumbing professional for the installation or maintenance procedures. The beauty of the countertop RO system is that you can take it along with you easily if you decide to move houses.
  • Undercounter RO system: The model is also known as the under-sink RO system, and it’s the most common type of all manufactured RO systems. It is installed under the kitchen faucet, and its installation procedure is not as easy as that of the countertop system. But once you have it up and running, it’s easy to use and maintain. Just turn on your faucet, and you will have at hand the most refreshing water your money can buy. Unlike the countertop model, the under-sink RO system can filter lots of water faster, making it the more convenient of these two models, when it comes to daily use. Having said that, some under sink models are more water wasteful during their filtration process.


There are many reverse osmosis water filtration systems out there at different price ranges. Make a budget and ensure that you only purchase what your pockets can handle. Some RO systems like the Express Water Reverse Osmosis Water Filtration System and the Whirlpool WHER25 Reverse Osmosis (RO) Filtration System are budget-friendly. Some other RO models will, cost much more. The Waterdrop RO Reverse Osmosis Water Filtration System is a little pricey.

Indeed, there are reverse osmosis models out there that are quite expensive. The expensive models often have more stages of water purification and other functions, such as the autoflush. They can also filter more water at a go, than the less expensive models. A costly RO system could also have water remineralization features, which ensures that your deionized water has more nutrients and minerals for your health. Cheaper products may not have a hardy construction for durability, so you have to check the reviews before purchasing a very low-cost item. If you do not have a hefty budget for an RO system, buy one in the mid-range.

Water filtration quantity

Reverse osmosis systems vary when it comes to the amount of water that they can filter in a day. Some can handle 50 gallons, while others can filter over 100 gallons in a day. A 50-gallon model will adequately supply a small household, but a larger home will be inconvenienced by it.


RO systems often reference the number of water filtration stages inbuilt in them. A four-stage RO system will have pre-filter, the RO membrane as well as two other carbon filter cartridges for enhanced water filtration. If your water is not highly polluted, a simple three-stage RO model is sufficient for your water filtration needs. Having said that, if your water tests positive for high contamination, a five or six stage RO model will do an exhaustive water filtration job.

Ease of installation

Under the counter, RO models are not very easy to install, so if you purchase one, you might need to call in a professional for assistance. If the system’s process of installation is too complicated, it might force you to pay more than average for the process.

Replacement filters

Most reverse osmosis models have different stages of filtration, which means that they do have different filter change maintenance processes. They could also require a system clean, which could be complicated depending on the model you purchase. If you are looking for an easy to maintain RO system, buy one with long-life filters and with features such as autoflush. If you buy a model that needs constant maintenance and you cannot keep up with it, you might end up with a malfunctioning RO system.

Wastewater created

One of the most significant disadvantages of reverse osmosis water filtration products is that unlike other water filtration technologies that do not waste water, RO systems create water waste as a byproduct of the filtration process. Some RO systems only recover about 5 % to 15% of filtered water. But there also other RO systems that have recycling features such as repurposing the waste for use in laundry or dishwashing. Such models are often referred to as zero waste models. If you are very environmentally conscious and have decent treated municipal water supply, go for other environmentally friendly methods of water filtration.


Reverse osmosis systems are big-budget items, and you do not want to commit to one that will not last some years of use. They are also not easy to install, so disrupting your kitchen’s plumbing system for a short-lived product is a no-no. Go for a brand that is solidly reviewed and with a respectable brand history. Look for models with excellent warranties, especially those with lifetime guarantees.

Source water

Most homes in the US either use ground or city water. Water in urban centers has already gone through a water treatment plant before it is channeled to homes. Therefore, it has less contamination than most other water sources. Entry-level three stages RO models will work well for pre-treated water. However, if you live in a suburban area, your water could be from ground sources such as private wells. Water from these sources could have higher levels of contamination, especially bacteria, viruses, and other microorganisms. Thus, you will need a robust RO system, coupled with UV light sterilizer features to ensure absolute water safety.


Despite its propensity to wastewater during filtration, reverse osmosis produces the purest water just as nature intended it. These RO water systems will provide ample water filtration for your household. Our favorites are the Home Master TMAFC Artesian Reverse Osmosis Water System for its filtration prowess and long-life filters. We also love the APEC Water Systems RO-90 Ultimate  High Output 90 GPD for its extensive capacity filtration for larger households, features, and affordability too.