Best Reverse Osmosis System Reviews 2019 – Top RO Water Filters

With concerns about the environment being a common issue in the news, it’s no wonder that even tap water in your home can get contaminated. Those who think that the water they get from their tap is safe, have a lot to learn. Certain chemicals, such as chlorine, which should clean water, can endanger your health over an extended period. Besides that, the coating which is inside municipal and your home’s pipes can also affect your body. Little by little, these coatings can accumulate in your system and cause negative symptoms.

The benefits of having a steady supply of clean water with the help of an RO system are vast. There are advantages for your health, for the environment and your finances, among others. In our efforts to bring potential buyers closer to making a decision, we have chosen the best units in four different categories.

These categories include the best seller, the top pick, the best portable RO system and the best under sink RO system. With the help of our reverse osmosis water filter reviews, you will have no trouble picking an option that suits your requirements.

iSpring-RCC7 Reverse Osmosis System

1. iSpring RCC7 – Best seller

The RCC7 from iSpring is a best seller, and for a good reason. This under sink unit has an impressive five-stage filtering process and can treat up to 75 gallons of water each day. The output that this unit can provide makes it the best RO system in its class. With five different steps in treatment, you can expect the RCC7 to filter up to 99% of pollutants from a water feed. There are more than 1,000 contaminants that Ro unit can remove. These include chlorine, fluoride, lead, arsenic, various pathogens, pesticides, sulfur, etc.

Installing the RCC7 is made easier with quick fitting connection lines. In total, there are four different line colors which ensure you don’t make a mistake during setup. You will also notice that a few spare parts come with the package in case you need replacements or break any during installation. For those of you worried about size, this RO system can fit under most sinks. But, you should always check product dimensions to be certain.

Along with this simplified method of installation, there is an official DIY video and customer support. If you happen to have any trouble with your iSpring unit, know that there’s a lifetime of tech support offered. Moreover, as a customer you get a 1-year warranty and 1-year money-back guarantee. As a bonus, this osmosis system comes with a durable European style faucet made out of brushed nickel with various finishes.

When it comes to performance, the RCC7 backs up its claims with a gold seal certification from the Water Quality Association. But, it is also highly praised by verified Amazon users. If you need a home reverse osmosis system that’s durable, reliable, and performs to specifications, look no further.


2. APEC ESSENCE ROES-50 – Top Pick

Our top pick for a home reverse osmosis system is the APEC essence roes-50. This model from APEC is 100% USA-made which corresponds to the quality of its parts and performance. If you have a high total solids count in your tap water, this is the RO system for you. The Roes-50 removes up to 99% of pollutants and impurities with its unique 5-stage process. It can remove arsenic, lead, fluoride, chlorine, bacteria, and viruses, among 1,000 other contaminants. For the money, this unit performs like no other osmosis system. It puts out 50 gallons per day of clean, filtered water with a 4-gallon storage tank.

To install the Roes-50, you don’t have to be an expert. In fact, everything is straightforward, while only requiring a few common household tools. APEC has developed quick connect fittings which do not need clips to prevent leaking. This tubing is color coded to avoid any mistakes during installation. For added safety, all the tubing is FDA and NSF certified as food grade. Included in this under sink osmosis system is a lead-free faucet with a chrome finish.

The Roes-50 and all its parts have been rigorously tested to conform to the highest of standards. This means that you’re getting an RO system that needs less service than most other units on the market. What’s more, the operating noise is minimal thanks to metal construction. There are also fewer clogs and leaks to worry about and fix. Furthermore, water recovery with the Roes-50 is high thanks to a well-tuned system that uses less water for rinsing and has an automatic shut off.

APEC has more than twenty years of experience and produces high-quality osmosis systems. Their dedication to being the best shows more than anywhere else in the Roes-50 and its performance.

TMAFC Artesian Undersink

3. Home Master TMAFC Artesian – The Best Under Sink RO System

For those that can afford a premium price-tag come premium features. The best under sink RO system among our reverse osmosis water filter reviews is this Home Master model. The TMAFC Artesian offers a lot in a small package. With this unit, you can remove up to 98% of contaminants in seven filtering stages. Besides that, it can add magnesium and calcium minerals to your filtered water through the included faucet. What this does is improve the taste by making it somewhat alkaline. Thanks to an impressive flow rate and 50-gallon daily output, you will never be without clean water.

Even though this is a top level product, it doesn’t need much more than DIY know-how to install it. Set up is fast with the use of color-coded tubing and a quick connection system. All you need to know comes in the instruction manual that ships along with the TMAFC Artesian. But, if you require help, you can always take advantage of live customer support or find answers in installation videos.
Once set up correctly, this reverse osmosis system cost little to run and service. The filters included with this unit from Home Master are long lasting and efficient. The filters are also easy to change without the need for wrenches and can purify up to 2000 gallons before needing replacement. This number translates into a year of uninterrupted service. When it comes to the recovery rate, this Home Master unit has a 4:1 ratio. This means it disposes of 1 gallon of water per 4 gallons of purified water.

The TMAFC Artesian solves many of the problems related to standard RO systems. It adds minerals back into filtered water, has an increased rate of flow and its seven stage process is unrivaled.

0PPM Portable 50 GPD

4. 0PPM Portable 50 Best – Portable RO System

We all know how the benefits of using a home reverse osmosis system. But, what to do you do if you don’t have the space to install a classic RO system? That is where the 0PPM Portable 50 comes in. This high-quality filtering unit is ideal for use in a rented apartment, for boats, RVs, and mobile homes. You can also take with you on vacations and business trips because it weighs only 4 pounds. It might not come with all the features of standard osmosis units, but it is much cheaper. That’s why we have chosen it as the best portable RO system.

To install this osmosis system, you don’t need any special tools or knowledge. The individual filtration stages connect to each other with special clamps and flexible tubing. Once you attach all the filters, you just have to connect the intake hose to a faucet and collect the clean water that comes out. One thing to note is that you have to have a faucet with an inner thread. But, you can always carry a small, lightweight adapter with you, just in case. With a waste water output and hose, this RO system can divert waste water output into a sink or drain.

When it comes to performance, the reverse osmosis system isn’t lacking. It can remove 99% of all contaminants and pollutants. This includes sodium, aluminum, lead, arsenic, mercury, and various bacteria. For optimal performance, this unit needs a water pressure of 40-80 PSI. The pre-filter can work up to a year and produce at most 4000 gallons of clean water. In contrast, the membrane lasts up to two and a half year and can produce anywhere from 50,000 to 100,000 gallons of filtered water or some 50 gallons per day.

Reverse Osmosis System Reviews – UPDATED LIST 2020

Express Water RO5DX

5. Express Water RO5DX

Express water is one of the better water filtering brands available on the market. Their RO5DX reverse osmosis filter comes at a lower price but offers quality parts and excellent performance. If you buy this RO system, you will get everything you need to set it up under your sink, as well as an extra filter set and faucet. Thanks to color coded tubing and simple connection system, setup is quick and easy. If you do hit a snag, customer support is always there to help you out.

The RO5DX utilizes a five stages process for filtration. It removes everything from silt, dust, and rust, up to the finest contaminants. On top of that, it has a fifth and final polishing filter which removes any remaining odor or unpleasant taste. This osmosis unit could come with better fittings, but it is not a significant drawback.

APEC Top Tier ULTIMATE RO-90 Review


For those of you that need a top rated reverse osmosis water filter system, this APEC is a good choice. The Ultimate RO-90 has a gold seal from WQA and removes up to 99% of pollutants. The filters that come with this unit have a higher capacity and last twice as long when compared to standard ones. This under sink RO system uses a five-stage filtration process which softens and purifies your water.

The capacity of the RO-90 is 90 gallons per day (60PSI), but it may be lower depending on household water pressure. With this RO system, you will get a 4-gallon storage tank with automatic shut off and food grade tubing. Installation is simple and relies on a detailed instruction manual. All the fittings necessary to complete setup come with this reverse osmosis system. The only downside is that there is no re-mineralization feature, but none the less, the RO-90 from APEC is a worthwhile investment.

iSpring RCC7AK Review

7. iSpring RCC7AK

Among our reverse osmosis system reviews, the RCC7AK from iSpring is a unit that stands out. For a somewhat larger price-tag, this RO system offers both excellent filtration and remineralization. With a six-stage process, the filters in this unit can remove 99% of more than 1000 pollutants. Because of its performance, this osmosis system has a gold seal from the Water Quality Association. The RCC7AK has a larger than usual capacity of 75 gallons per day and can even put back minerals in filtered water. For peace of mind, there’s a one-year warranty and one-year money-back guarantee.

To install the RCC7AK, you can follow a straightforward instruction manual and videos or use customer support. All the tubes for this unit are color coded and use a quick connection system. Like with other premium products, there is a separate faucet included with this unit. It has a brushed nickel finish and brass body.

Home Master TMHP HydroPerfection Undersink Review

8. Home Master TMHP HydroPerfection

If you don’t want to spare any expense for water filtering, then the TMHP HydroPerfection is for you. This home reverse osmosis system comes with some impressive features. There is a total of nine filtration stages in this unit. They purify, filter, UV sterilize and enhance to produce ultra clean water. Using this unit, you can remove 98% of various chemicals, solids, heavy metals and iron. Moreover, there is a remineralization feature that prevents damage to the storage tank and improves taste.

Setting up this under counter reverse osmosis system doesn’t require any special tools. High-quality color coded tubing and connection ensure easy installation and optimal performance. There’s a feed adapter in the packaging (1/2″ and 3/8″). Maintenance is easy thanks to modular filter design, and these long lasting filters need to be changed only once a year after 2000 gallons. Finally, there’s a five-year limited warranty against defects included.

Watts Premier RO-Pure Review

9. Watts Premier RO-Pure

Another good choice in our top list is the RO-Pure from Watts Premier. This reverse osmosis water filter system has four stages in the filtration process. The first two steps remove silt, dust, and rust, as well as bad taste and odors. The third stage, an RO membrane, removes other harmful chemicals and organic pollutants. The final stage is a carbon filter which further improves the taste of your water.
Installation of this reverse osmosis system requires more tools than usual, but most of them are found in every household. Inside the box, you get all the parts you need, including an air gap faucet. With everything set up, you can expect up to 50 gallons of clean water per day from this RO system. When indicator light shows that you need to replace your filters, you won’t need any tools. The filters have their housing and are replaced as a whole with the push of a button.

APEC US Portable RO-CTOP Review

10. APEC US Portable RO-CTOP

The final reverse osmosis system in our reviews is the Portable RO-CTOP from APEC. This unit is a light, compact size RO system that is ideal for people on the go. You can use it while traveling, in mobile homes, RVs, dorms and any other places that have a faucet. Although it has a steep price-tag, it comes with a 4 stage filtering process. This APEC unit can remove 99% of contaminants like chlorine, arsenic, and lead while providing you with great tasting water.

Since this reverse osmosis system is portable, you can install faster than under-sink units. It is compatible with the three most common faucet types and doesn’t need special tools for setup. Despite the high price tag of the Portable RO-CTOP, we placed this reverse osmosis water filtration system in our top list. This is because of its high-quality filters which last long and are easy to replace. Finally, this APEC unit puts out up to 90 gallons per day.

Best Reverse Osmosis System Comparison Chart

Reverse Osmosis System Brands

The market for RO systems has many options to choose from, sometimes too many for it to be a straightforward choice. To help you avoid low-quality solutions or spending more money than necessary, we’re going to present some of the best brands in a short list. This way you can pick from the most reliable companies and save precious time as well as money. This is a list of some of the top reverse osmosis system brands in our opinion.


This company has been around for more than a decade with a base in Alpharetta, Georgia. iSpring is a family-owned brand with a specialty in RO filtration systems for water. Among their products, you can find both commercial and residential solutions. They offer whole house systems, systems for ultra-filtration, but also faucet, shower, and filters for counter tops. They also have filter housings and cartridges, RO coolers, and various fittings and faucets.

Their products have a high-rating with users of online retailers like in a multitude of categories. This isn’t surprising when you realize that they produce high-quality RO equipment. What’s more, they are a top rated seller on eBay. With all this in mind, we recommend them to anyone looking for a way to filter tap water and make it safe for drinking.

Home Master

For those of you that need a high-quality reverse osmosis system, Home Master is another great choice. This company has a broad range of products which include under-sink and sink-top systems, as well as whole house solutions. For each category, they have five or more solutions with different options and prices. That way you can find the one that suits your budget and meets your needs for water purification.

Trusted retailers like Amazon are full of positive reviews for Home Master products. You can also find at least one Home Master RO system among the list of best sellers. What is evident is that this is a brand dedicated to making reliable and long-lasting products. As a result, we think you should consider Home Master when choosing an RO system.

reverse osmosis brands


Apec is one of the leading US producers of reverse osmosis filtration systems. They have a base in the City of Industry, in California, which is a suburb of Los Angeles. This is where they come up with custom designs and manufacture all their solutions.

Apec has almost two decades of experience within this industry and a large as well as a loyal base of customers around the world. Their products find use in a variety of different locations and successfully overcome all sorts of problems. Moreover, they have solutions for industrial, commercial and residential purposes.

Apec RO systems are some of the most durable on the market. This company is among a minority of brands that have USA-made filters. For further proof or this brand’s quality, you can take a look at online shopping websites. Their products are universally high-rated and among top sellers in various categories.

Express Water

Express Water is another premier brand which supplies systems for reverse osmosis and filtration. Their proprietary technology is made for convenience and goes through strict quality control.
This company is located in Southern California and has been around for more than 25 years. Their products ship with straightforward and simple instructions, as well as a twelve-month guarantee for parts. One of the benefits of owning an Express Water solution is knowing that your reverse osmosis water system contains good quality parts.

With a substantial market presence, this company can offer RO systems at affordable prices without compromising quality. Having a full range of solutions for every budget further secures their place as one of the top brands in our opinion. This company has a good reputation among customers, which is evident in online reviews.

Watts Premier

Watts Premier is another well-known brand when it comes to RO system products. They are a US based manufacturer and own many different brands under the name Watts Water Technologies. This company has almost 150 years of history. It has transformed from a small machine shop to become a global player in heating, plumbing, and filtering solutions.

Watts Premier offers replacement parts and an impressive range of reverse osmosis systems. Their products are known for their ease of use and easy maintenance. All the positive user reviews on Amazon, for instance, testify to this fact.


The last company on our list of brands is Brondell. This is a manufacturer which started out by making Japanese-inspired bidets for the US market. Over time, they expanded their line of products to include water filtration systems that work with reverse osmosis. They also produce air purification systems. What ties these products together is modern technology and modern design.

When it comes to RO systems, they offer a few options which can blend in and work well in any kitchen. These systems include under-sink as well as countertop products. High-tech options and eye-catching design don’t come cheap, though. This means that Brondell is a premium brand with premium prices.


Because of negligent practices in various industries, using RO systems has become a necessity for most homes. The only way to make sure the water you are drinking is safe and clean is with one such system.
For those that are looking for a reverse osmosis water filter system, your best bet is to check out what the brands on our list offer. There are under-sink or counter top options as well as portable solutions, but also options with a different number of filtering stages. When you add up all the products between them, they can cover anything a homeowner could need.

Understanding Reverse Osmosis

The process of reverse osmosis can eliminate most impurities by pushing water through a special membrane. The water in an RO system gets squeezed using the pressure in your household. We will try to explain the basics of how this process works in simple terms so that everyone will be able to understand it. If you want to buy an RO system for your home, learning more about it should be your first step. By getting acquainted with the technology, you can know what to expect. You will also be able to understand better what the possible applications are.


For a better grasp of reverse osmosis, it is important to comprehend how osmosis works. Osmosis is a mechanism during which a less concentrated saline solution moves to a stronger one. For instance, this process happens when plants absorb groundwater through their roots.

Imagine two containers filled with water; one has a lower salt content and the other a higher salt content. Now imagine that there’s a semi-permeable filter or membrane between them. In this case, the low salt content water will always move to the side with the high salt content.

The semi-permeable membrane mentioned above only allows some molecules or atoms to pass. An example everyone can relate to is a screen door’s mesh. The door lets air pass but prevents anything bigger than the mesh holes to pass, like insects. A second example is a sieve used for cooking which can filter out solids but allows liquids pass through.

Reverse Osmosis

Osmosis is a natural process that happens by itself, but RO requires energy. A membrane in an RO system is semi-permeable; it lets water pass but holds back most dissolved bacteria, pyrogens, organics, and salts. The only catch is that liquids need to get pushed through this membrane.

The pressure necessary for this to work has to be higher than the osmotic pressure that happens naturally. When this is achieved, clean water goes through, while the membrane holds back many contaminants.

An osmosis system operates with a high-pressure pump which increases the pressure of the high salt content side. This pump forces water through the membrane which traps up to 99% of impurities. The rejected water gets discharged or recycled depending on the circumstances. RO systems use cross filtration which allows the water flow to remove any buildup of contaminants.

Why is reverse osmosis a good water filtration option?

taste water

Improves Taste

Among the many benefits of using an RO system is that it improves the taste, smell, and appearance of water. These improvements are due to the way the whole system works. An RO system’s semi-permeable membrane removes various contaminants from your water supply. Some of these impurities can cause water to look unpalatable or have an unpleasant odor and taste.

If you have any of these problems with your home water supply, you should think about getting a whole house reverse osmosis system. Once you’ve tried treated water, you will never want to be without an osmosis system.

Saves Money

Saves Money

We all know how much a service for water delivery can cost when you start to add it all up. But, you can go ahead and cancel it once you get your RO system installed. After you set up a reverse osmosis system, the saving starts.

Buying bottled water can’t compare to filtering with a high-efficiency system. First of all, you can get better quality water with filtration, and secondly, it’s incredibly cheap. You can have better quality drinking water than bottled options for a few cents per gallon.

Simple maintenance

Simple Maintenance

Osmosis systems have a design that is hard to beat when it comes to servicing. There are no more than a few moving parts which are easily replaceable. Even if something breaks down, you won’t have trouble sourcing replacements or installing them. Many owners of these systems do repairs by themselves which prove just how simple maintenance can be.

What’s more, cleaning an RO system is also straightforward and doesn’t take up a lot of time. This can bring down costs further and maximize your investment while offering a whole range of benefits.

Clean Water

Removes Impurities

One of the best aspects of any given RO system is the ability to remove impurities. It is well known that many water supplies around the world are contaminated with various pollutants. These pollutants can include pesticides, nitrates, fluoride, sulfates, arsenic, pharmaceuticals and much more. What’s more, a carbon filter can also remove chloramines and chlorine.

Some of this pollution stems from agriculture, some from industry, while other impurities are natural. Whatever your situation may be, an osmosis system can clean up your water and make it safe for drinking. Moreover, it even makes water taste better.

History of RO systems

Those who think that the water they get from their tap is safe, have a lot to learn. Luckily for everyone concerned with their water, reverse osmosis systems can remove most contaminants and impurities thus making water safe to drink. These systems are widespread and are used in many homes as well as by municipalities around the world. Over the years, they have become an inseparable part of everyday life, but what are the origins of RO systems? We’re going to take a look at the history of osmosis systems and bring you up to speed.

Jean-Antoine-NolletDiscovery of reverse osmosis

In 1748 French scientist Jean-Antoine Nollet discovered reverse osmosis through one of his experiments. He employed a semi-permeable membrane and started it all off.

First tests for commercial use

In 1949, after two centuries of reverse osmosis being only a lab experiment, interests in purifying water grew with the end of World War 2. Water desalinization tests began in Los Angeles at the University of California. American scientists wanted to remove salt from ocean water and use it for drinking

In the 1950s UCLA and Florida University manage to produce clean water from seawater. Unfortunately, the flow rate was lower than needed for commercial viability.

Improved RO membrane and commercial viability

In 1959 a researcher from UCLA named Sidney Loen and his colleague from Canada, Srinivasa Sourirajan, came up with a better membrane for reverse osmosis. They used new, synthetic materials which provided better performance. This new type of membrane worked like a filter during different tests. Namely, they forced high salt concentration water through it and had incredible results. The membrane trapped salt while letting fresh water through. Moreover, their new invention was effective enough when it comes to flow rate, so RO became commercially viable.

Their idea was to come up with a different technique which made asymmetric membranes with a thinner skin layer. This layer was then put over a porous substrate area that was much thicker. The new type of membrane allowed a great flow rate, and the membrane itself was durable. What’s more, it was even able to filter water under normal pressure. This process got the name reverse osmosis because the water flowed in reverse in comparison to osmosis.

First water treatment plant

In 1965, the first ever RO plant for water treatment opened in California, in a town called Coalinga. Leading scientists in the field oversaw the building process and offered help. This project received an incredible amount of press and attention. What’s more, engineers from all four corners of the globe followed the building process. The ultimate goal of this project was to turn saltwater into drinking water in an affordable way and on a larger scale. There were other projects in different cities in California which tested various types of saltwater. The primary beneficiary of this technology would be heavy industry because significant amounts of clean water were now available through this method.

In 1977, the first ever municipality to employ RO on a large scale was Cape Coral in Florida. They were able to produce three million gallons of clean water every day. At this point, RO systems caught on, and public interest started to rise.

By 1985, Cape Coral expanded its production and water treatment plant as the population of this municipality grew. In other words, they were able to raise production to 15 million gallons per day and become world record holders.

Introduction of home solutions

From the 1990s onward, the first home reverse osmosis systems were on the market and available for sale. The patent held by Caldotte for membranes became the standard for almost all RO membranes that were commercially available. By the year 2000, more than 15,000 plants for desalinization were either operating around the world or getting built. These large scale plants are part of the goal to prevent clean water from being depleted, while membranes can serve many purposes. The water treatment industry continues to grow from year to year. But, this is not surprising because clean and safe drinking water is going to be a valuable resource. The main reasons for this are the fact that all living beings need water, and that pollution and environmental changes pose a significant threat.


Nowadays, a lot of cities and towns have at their disposal water that has been purified with RO. Those that do not have this privilege can decide to use a residential system. As a homeowner, you can always install a home reverse osmosis system. Thanks to health trends, it’s easier now than ever to find a treatment solution for your tap water.

There is a range of products available on the market today that can cover any set of needs. You can meet your budget, size or safety requirements easily, among other ones. Water filtration by RO has come a long way since its discovery and first commercial use. Every component has been reduced in size while filtering power has increased. Once only used by public facilities, now you can treat the water in your home with a unit that fits under a sink. It may not register with someone who is looking for an RO system while choosing from different brands, but one thing is sure. Reverse osmosis is here to stay because it’s crucial to the future of humanity.

How does reverse osmosis work?

It’s a straightforward water filtration process

Through the process of reverse osmosis, solid impurities like salt get removed from the water. This is done by using your household water supply which pushes water through a special membrane under pressure. Among the contaminants that an RO system can remove are:








Chloramine and Chlorine


Nitrates and Sulfates


Detergents and others

Although public water supply companies dedicate themselves to providing clean water, they don’t remove as many impurities as an RO system can. This is because many contaminants aren’t regulated, most often those that tend to affect the taste of water.

Four stages in the reverse osmosis process

Sediment filter

The first step in purifying your home water is a sediment filter. This pre-filter removes things like dirt, silt, and sediment. This part of the processing is important because it stops sensitive membranes further down the line from getting damaged. After this stage is complete, the largest of impurities get removed from your water supply. You can think of a pre-filter as a net which catches and holds particles that are too big to pass through their holes. The best filter for sediments is the one that cleans your water and has a long lifespan while restricting flow the least.

Carbon filter

A carbon filter removes things like chlorine and other pollutants that can be detrimental to the reverse osmosis membrane. These contaminants can affect both the life span and the performance of membranes. Water that has passed through a carbon filter ends up having a better taste and smell. Reverse osmosis with carbon filtration give the best results. This is because this combination can handle almost any impurities. These include bacteria, viruses, parasites, arsenic, iron lead, aluminum, pesticides, herbicides, etc. In short, anything that might be an issue in your household a carbon filter can remove.

Reverse osmosis membrane

One of the last steps in water filtration is a reverse osmosis membrane. These are the finest membranes out of everything so far and separate some of the last impurities. These membranes allow water to pass through them but collect contaminants. The best reverse osmosis system can remove up 99% of pollutants during this part of the filtration process. For the best results, you should make sure that your system has the right membrane to cover your needs. Moreover, the quality of filters and membranes in your RO system will have a significant impact on performance.

Polishing filter

If you are lucky enough to be the owner of an osmosis system with four stages, you will have one final filter, the polishing filter. This is another carbon filtration step which that removes any remaining smell or taste. What you end up with is high-quality drinking water that’s above all safe. In fact, you get ultra-pure water or Type I water this way. A polishing filter is used to remove small traces of impurities from pre-treated water. It can consist of deionization through mixed beds, activated carbon, organic scavenging solutions and a final filter.

What happens to the impurities that don’t pass through the membrane?

All the filters in an RO system help capture impurities using the pressure of your household water supply. These filtered impurities later end up in the drain. What you’re always left with is a safe and clean supply of water that tastes and smells like it should. You should be aware that most osmosis systems have four or five stages of water filtration which guarantees optimal quality.

Another fact worth knowing is that reverse osmosis is not a new technology by any means. Municipalities began using this process in the late 1970s. It has since been adopted in many homes and commercial settings.


Basic components of a reverse osmosis system

Most often, a residential RO system also known as a “Point of Use” system is installed bellow the sink in your kitchen. When it comes to standard components in four or five stage systems, you should know the following:

  • Virtually all osmosis systems share basic parts and look like each other.
  • Even though most of these products look and work similarly their components can differ in quality.

These are the basic elements of RO systems:

Cold water line valve

This is a valve that’s mounted to the supply line for cold water. This valve contains a tube that gets attached to the inlet side of a reverse osmosis pre-filter. Your RO system gets its water from through this valve.


Water coming from the cold water supply line first goes through a pre-filter. An RO system may use more than one pre-filter to clean your water. Most often, these are carbon and sediment filters. The job of pre-filters is to protect the reverse osmosis membranes by removing dirt, sand, and silt. A pre-filter prevents the membrane from getting clogged by larger impurities. Moreover, a carbon filter can eliminate chlorine from the water which can also damage an RO membrane.

RO membrane

The reverse osmosis membrane is at the heart of each filtration system. This membrane can filter many different contaminants that can make water unsafe or unpalatable. Once water passes through this membrane, it gets diverted into a storage tank that is under pressure.

Storage tank

Most storage tanks can hold two to four gallons of treated water. The pressure in the tanks is maintained with the help of a special bladder. A common RO tank that fits under your counter is about 12 inches in width and 15 inches in height.

Post filters

There’s one more step in the process before the water goes to the reverse osmosis faucet – it has to go through a post-filter. The post filter is often a carbon filter. The task of this filtration stage is to remove any taste or odors that weren’t removed in previous steps.

Automatic shut off valve

For water conservation, an RO system contains a shut-off valve that is automatic. This valve prevents more water from entering the system when the storage tank is full and blocking water flow to the drain. When water is taken from the reverse osmosis faucet, the pressure in the storage tank drops. After that, the shut-off valve opens up to supply filtered water through the membrane while wastewater goes down into the drain.

Check Valve

The check valve can be found on the membrane house, at the outlet end. This valve stops backflow of filtered water from your storage tank. If not for the check valve, a backward flow could destroy a reverse osmosis membrane.

Flow restrictor

The flow restrictor regulates all the water that flows through the RO membrane. Flow controls differ, but they’re used to sustain necessary flow rates depending on the membrane capacity. Flow restrictors also maintain inlet side pressure. The flow control provides extra pressure to a system which prevents water going down the drain line, by taking the path of least resistance.


A reverse osmosis system has its faucet, which is often located in the kitchen sink. Regulations might require a special air gap faucet, but models without this gap are the most common.

Drain line

The drain line goes from the outlet end of an RO membrane all the way to the drain. This line gets rid of contaminated water and filtered impurities from the RO membrane.

Reverse Osmosis Performance Calculations

An RO system’s performance can be judged in a few ways. An osmosis system can display pressure, flow, quality and even temperature parameters. To judge your RO system performance with accuracy, you will need at least six readings. These readings are salt passage, recovery, concentration factor, flux rate and mass balance.

When shopping for a reverse osmosis system, you should always have the ability to read these parameters. Otherwise, you’ll have a hard time judging how efficient your system is, or how much money you can save by using it in your home.

Salt rejection

Salt rejection shows you the effectiveness of RO membranes in removing impurities from water. Salt rejection is measured in percentages. It doesn’t show you the performance of individual membranes; it shows how the whole system performs on average. An RO system that has a god design and high-quality membranes can reject 99% to 95% of contaminants from your water. To determine how efficient your reverse osmosis membranes are when it comes to removing impurities, you can use this formula:

salt rejection calculation

If salt rejection is higher, then your system is performing better. If your system has a lower salt rejection, you might need to clean or replace your RO membranes before getting a better result.

Salt passage

Salt passage is the reverse of the salt rejection parameter which we explained above. Simply put, this describes the amount of salt (in percentage) that pass through an RO system. A lower salt passage percentage means that the system is performing better. On the other hand, a higher salt passage rate might be a sign that your membranes need maintenance or replacement.

salt passage calculation


Percentage of recovery is simply the quantity of good water that gets recovered. A high recovery rate means that more product water is getting saved and less is getting sent to the drain. But, if an RO system’s recovery percentage is higher than what its design allows, you can end up with problems caused by fouling or scaling.

The rate of recovery for a reverse osmosis system is set with special software. This design software considers things like the chemistry of feed water and pre-treatment prior to the osmosis system. Thus, the right recovery percentage of a system depends on its design. If you want to find out whether your system is running as intended, you can calculate the recovery percentage. This calculation can be achieved with a simple formula:

recovery calculation

Concentration factor

An RO system’s recovery is tied to the concentration factor and is an important aspect of design. With more reclaimed water you get a higher concentration of salt and impurities in your concentrate stream. What this leads to is a higher chance of buildup on a membrane if the level is greater than what the design of your system and the composition of feed water allow.

concentration factor calculation

For instance, if you have a feed flow of 80 gallons per minute and the flow of permeate is 40 gallons per minute, then the amount of recovery is 50% (40/80 x 100). To calculate the factor of concentration, you would use this formula: 1 ÷ (1-50%) = 2.

If your concentration factor is 2, then the concentrate will have a level 2 times higher than that of your feed water.

Flux Rate


Here’s an example:
An Osmosis system produces 60 GPM of filtered water. If you have 2 RO vessels with eight membranes each, then there are 16 membranes altogether. Let’s say you have membranes in your system and each has a surface area of 360 square feet. To find out the flux rate (GFD):

gfd result

Your flux is 14.8 after rounding.

What this means is those 14.8 gallons come through every square feet of every membrane each day. Based on the feed water and the design of a system, this number can be bad or good. It is always important to know what kind of membrane you will be using and to use the same type throughout your system.

Mass Balance

To determine whether your quality and flow readings are correct or need further adjustment, you can use a mass balance equation. To perform this calculation, you will have to gather specific information from an osmosis system as shown below.

The equation for Mass balance is:

mass balance calculation

Here’s an example:


Permeate Conductivity = 9 µS


Concentrate Flow = 1.5 GPM


Concentrate Conductivity = 1000 µS


Permeate Flow = 4 GPM


Feed Conductivity = 400 µS

Feed flow is Concentrate Flow + Permeate Flow
(400 x 5.5) = (9 x 4) + (1000 x 1.5)
2,200 ≠ 1,536

Calculate what the difference is

(Difference divided by Sum) x 100
((2,200 – 1,536) / (2,200 + 1,356)) * 100
= 18.7% after rounding

A difference greater than + or – 10% requires calibration for correct data collection, while 5-10% is acceptable.

RO system service and maintenance tips

RO systems are used in many homes and offices for their ability to filter out almost all water contaminants. These units are always improving, but even the best reverse osmosis system needs maintenance. To help you achieve optimal performance with your filtration unit, we’re going to share a few tips. That way you will be able to prevent damage to your unit while having a steady supply of clean water.

All RO systems have multiple filter stages. You can have anything from three stages to seven or more. We won’t go into detail for each stage, but we will cover basic maintenance tips. These tips apply to the majority of RO systems.

Filter Maintenance

For the protection of sensitive RO membranes, water first goes through a pre-filter. These filters remove dirt, sand, silt, and other similar contaminants. They should get changed once every 6 to 9 months. When a pre-filter isn’t replaced according to manufacturer instructions, you might clog it and risk damage to an RO membrane.

Once your water passes through the first stage, the next step is a carbon filter. The purpose of these is to remove chlorine which might damage an RO membrane. Their secondary goal is to eliminate contaminants which cause a bad taste or odor. This carbon filter should also get replaced every 6 to 9 months.
The third stage of filtration is when water passes the RO membrane. This membrane lets clear water pass and holds back contaminants. Filtrated impurities get diverted into the drain and disposed of. Most RO membranes have to be replaced every 2 to 3 years.

The final stage in a reverse osmosis system is carbon post-filtering or polishing. This step removes any taste or smells the previous steps missed. To make sure these filters perform to specifications, you should replace them every 6 to 9 months.

You should be aware of the fact the lifespan of these parts depends on usage and local conditions.

ro system service

Water Pressure

Your household tap pressure should be checked from time to time. Each RO membrane has a cracking limit which is set by the manufacturer.


With regular check-ups, you can prevent the buildup of organic growth around outlets and spot leaks. RO systems are built from materials that discourage the growth of mold, but outlets are a weak spot. Another simple thing you can do to prolong the life of your unit is to clean the pipes or hoses.

When it comes to cleaning the inside of your reverse osmosis system, it is best to call a professional. This type of cleaning requires four or more hours to complete and the use of special agents. Furthermore, you have to take great care not to damage filters, and you need to measure pH values along the way. Cleaning frequency depends on fouling and other parameters, but should be performed every 3 to 12 months.

Softening Hard Water

Some areas have hard water which might damage your RO system. If you live in one such area, you might need to use a water softener before your unit.

Clean water benefits

Water is a necessity of life. Every person on this planet needs a steady supply of clean water. Contaminated water and the negative consequences associated with its use are well known. But, don’t think that you are safe just because you have municipal tap water. Even though many cities use state of the art methods for treatment, they can’t remove all the harmful components. Depending on where you live, there might be much more in your water than H2O. You could be ingesting harmful contaminants which fly under the radar of regulations.

Clean water has many benefits, but not everyone has access to it. Some supplies can contain things like lead, copper, barium, and arsenic or organic pollutants. With reverse osmosis filtration, you can remove impurities and make sure you are doing everything you can for your health. By drinking from a safe and clean source, you can avoid kidney stones, enjoy better digestion, and reduce chances of dehydration, and so on. For your body to function optimally, you need a large enough intake of water, so it should always be clean. Besides your health, there are also environmental, financial, and a few contextual benefits to clean water.



When it comes to using clean water, there are some distinct financial advantages. First of all, you will have less plaque build-up because RO systems remove harmful minerals. By using this method of filtration, you will also have an unlimited supply of water as long as you maintain your system. Reverse osmosis is as good as or even better than bottled solutions regarding quality, and especially when it comes to saving money. Operating an RO unit can cost as little as 30 cents per day. The most important financial aspect of clean water is the benefits to your health. Over a longer period, you can develop one of many possible health problems that stem from the consumption of unsafe water. That’s why the best way to save money is to keep your health. Think of all the hospital bills you might avoid just by making sure your water is clean.



Humanity’s toll on the environment might be a disputed topic, but one thing is for certain. Most people don’t want to add to the destruction of the environment. When you consider that most power comes from coal power plants, the best thing you can do to help is to save energy. By doing this, you will cut down on pollution and can do your part in the reduction of carbon emissions. You can easily find a whole house reverse osmosis system that doesn’t need any extra energy. With these units, clean and safe water is produced just with the pressure of your household plumbing. Having a house with the latest and most convenient systems doesn’t necessarily mean that the planet is worse off. After all, technology has come a long way, and many manufacturers care just as much about our planet as you do.



The practical or contextual benefits of using clean feature are also significant. For instance, with an osmosis system, you can reduce the concentration or completely remove some contaminants. Among these contaminants is chlorine. Chlorine tends to impart a particular taste in water as well as a smell that can be unpleasant to some people. Unfortunately, for everyone, cities can use a lot of chlorine to sanitize their water supply. Moreover, clean and softened water doesn’t stain your kitchen utensils, pots, and pans or sink. You household plants or any pets that you might have will also benefit from the use of clean water. These are just some of the contextual advantages, but you might discover much more through the utilization of an RO system in your house of business. Other benefits take some time to become apparent, like benefits to your health, but in the long run, you will always be better off using clean water.

Pretreatment Solutions

To prevent frequent cleaning or part replacement, you should consider using pretreatment solutions. Chemical and mechanical treatments also prolong the life of your RO membranes making a system more efficient and cost-effective. The problems related to water filtration are fouling and scaling.

Fouling happens when impurities gather on a membrane’s surface and start to clog it. Fouling occurs sooner or later, but you can delay it with proper pretreatment and bring operating costs down.

Scaling happens when the concentration of inorganic impurities rises and they stop dissolving. This leads to these compounds getting deposited on a membrane and restricting flow.

Antiscalants and scale inhibitors

Scale inhibitors and antiscalants are, as the names imply, special chemical solutions which reduce scaling. They can be an addition to your feed before a reverse osmosis system. These chemicals for anti-scaling raise the solubility of the problematic inorganic matter. With an increase in the limit of solubility, you can have a higher concentration of salts. This then lets you have a higher rate of recovery. With the use of scale inhibitors, it is also possible to have a larger factor of concentration.

Antiscalants and similar products stop scale from forming and prevent crystal growth. To find out which solutions you should use, you will have to know the composition of your feed water and its chemistry. Another important aspect of the application of inhibitors is using the right dosage. Finally, you need to be aware of the design of your RO system and what it can handle to avoid unnecessary damage.

Granular activated carbon (GAC)

Granular activated carbon or GAC removes organic components and residue from disinfecting chemicals. The primary disinfecting agents are chloramines and chlorine, among others. Coal, wood or nutshells make up the media of granular activated carbon. Activated carbon eliminates chloramines and chlorine by way of a chemical reaction. This chemical reaction moves electrons away from the GAC surface to chloramine or chlorine molecules. What you end up with is an ion of chloride that doesn’t act as an oxidizer anymore.

The downside of putting a granular activated carbon before your RO system is that GAC eliminates chlorine at the top of its bed. As a result, the rest of this bed doesn’t have biocide to remove various microorganisms. This type of filter takes in organic matter throughout the bed which can serve as food for bacterial organisms. In the end, you can end up with a filter bed that is teeming with bacteria and which can make their way to a reverse osmosis membrane. Moreover, these beds sometimes produce small fines from carbon which can foul your system. Fouling can cause an increase in pressure and a higher cost of operation.

Microfiltration (MF)

Microfiltration is an effective method of removing bacterial matter from 0.1 to 10 micrometers in size. This type of filtration helps reduce fouling in an osmosis system and helps lower costs. The configuration of these membranes differs across products, but the type with hollow fibers is most common. Usually, clean water gets collected on the inside and gets pumped from outside of these filters.

Membranes used for microfiltration of drinking water work in systems with dead end flow. What this means is that the whole feed gets filtered through a membrane, not just one part of it. This causes a filter cake to form from time to time on the membrane which requires a backwash. When you have a clear and high-quality feed going into your RO system, you can expect a high rate of Recovery. Most of the time, you can expect a rate that is greater than 90%.

Multimedia filtration (MMF)

Fouling can be prevented with the use of a multimedia filter in a reverse osmosis system. This kind of filter most often has three media layers. In these layers, there is anthracite coal, garnet, and sand, with the addition of gravel down at the bottom. The decision to use these components is because they have a difference is density and size. Anthracite coal is large but lightweight and sits on top. Garnet is heavier and smaller, so it sits at the bottom.

This type of media setup is ideal because the largest impurities get removed at the top and smaller particles near the bottom. A multimedia filter can remove particles down to 15 microns in size. Some media filters even have coagulant which makes small particles form clumps large enough for filtering. This way they can remove microscopic particles up to 5 microns in size.

Sodium Bisulfite (SBS) injection

Another pretreatment method that you might want to consider is the use of Sodium Bisulfite or SBS. SBS comes in the form of an injection which you can add to a water stream before it goes into an RO system. With a proper dose applied, you can eliminate chlorine residue from your water.

Sodium Bisulfite is a common agent for reducing chlorine levels. It is the pretreatment of choice for bigger systems. In theory, 0.7 PPM of SBS can remove up to 1 PPM of chlorine. For the best results, you should apply Sodium Bisulfite before any RO components and make sure it has at least 25 seconds to work.

The benefit of removing chlorine with SBS is that it’s more effective than filters with carbon for larger systems. Moreover, by-products get filtered by your osmosis system, as well as any remnants. The fact that you have to mix and handle chemicals is a downside to these SBS injections.

Softening by ion exchange

If you have hard tap water, another pretreatment that will prolong the life of your RO system is softening. Without softening, scale buildup can cause many problems and cause parts to wear faster. Scaling can diminish the effectiveness of RO membranes because of plaque and thus lower water quality. This leads to the early replacement of membranes and a higher cost of operation.

Ion exchange is a standard method to soften feed water. During ion exchange, hard water goes through a special cylinder containing resin beads. These beads are saturated beforehand with certain salts. When your feed passes through an ion exchange system like this, the ions which cause hardness are drawn to the resin and salt ions get released.

For added protection, you should place a 5-micron filter after a softener in case the softener underdrain fails.

RO may not be the best water filter for you

Reverse osmosis is an incredible technology, but it may not the right solution for every home or office. It has significant operating costs and requires regular maintenance as well as testing. RO systems were initially developed for two things:


Desalinization of sea water or brackish water and


Reducing the number of particular pollutants

If you have problems with sodium, fluoride, arsenic, nitrites or nitrates, you could use an RO system. There are many solutions available that can answer most needs and budgets.

Why reverse osmosis might not be for you

Although RO is considered the best way of purifying water, there are a few things you should know. RO’s reputation comes from military use. Military personnel need to be able to treat all sorts of water sources during deployment, but they do so with much more expensive equipment than the one for home use. They also use other ways of filtering like ultraviolet light, activated carbon, and so on. A reverse osmosis system for your home can remove salts, lead, mercury, calcium, asbestos and iron; it doesn’t remove others. These include pesticides, VOCs, and solvents.

Despite the fact that RO can reduce biological pollutants like viruses and bacteria, some membrane producers don’t have the necessary certifications to prove it. That’s why you should read the print if you decide to get a home system for RO filtration.

reverse osmosis cons



RO technology could be simpler and more cost effective

The majority of RO solutions need a steady water flow to flush and clean membranes. The water used in these steps ends up as waste. You can have anywhere from 20% to 80% can be removed as waste (concentrate). The water which a system puts out for drinking is measured with the recovery rate. When you get your bill, you are paying for everything, even what gets disposed of. A reverse osmosis system cost can be high because some solutions are notorious for having a low recovery rate.

When it comes to maintenance, RO membranes, and other filters need servicing and replacement from time to time. If you don’t service parts when necessary, you can end up with a destroyed membrane and dirty water. But, how do you know whether your membranes are working or not? You will need to run tests on treated and pretreated water regularly. RO also requires proper storage tanks, pumps, various pre-filters, and regular testing for it to work as intended. When all this is added up, you will need to invest a significant amount of time and money to get the most out of reverse osmosis.

Is RO water healthy after the minerals get removed?

The short answer is no if you consider the World Health Organization an authority on the matter. It is not recommended to use water low in total dissolved solids, as produced by some reverse osmosis systems, for very long periods of time. What’s more, a low mineral count can also affect the taste of your water.




Q: Where do I place an RO system?

A: In most cases, a reverse osmosis system ends up under the sink in your kitchen. These under-counter options have a storage tank and a few different filtration phases.

Q: What happens during reverse osmosis?

A: First phase
This part of the process helps protect the RO membranes of a unit. With the aid of pre-filtration, impurities, and contaminants which can cause blockages are removed.

Second phase
During this phase, chlorine gets removed from your water. This part is important because chlorine damages the film material of membranes.

Third phase
At this stage, the semi-permeable membranes come into play. They capture and remove many different contaminants. These can be impurities that affect the look and taste of water, but also your health.

Fourth phase
At the end of the reverse osmosis process, there is a carbon filter. This post-filtration step removes remaining contaminants that can affect taste, color or smell. This phase is also called the polishing stage.

Q: Can I connect my ice machine or fridge to an RO system?

A: Usually, an RO system that goes under your counter will get attached to a cold line, separate faucet, and drain. If you want, you can ask a technician to connect an RO solution to a refrigerator or an ice machine.

If you chose to connect these appliances, your installer would probably use a 1/4″ tube attach the osmosis system to your refrigerator. When doing this, you should consider the water pressure that your fridge can work with. For more details, take a look at the owner’s manual that comes along with your RO system. The pressure from an RO unit tends to be about 2/3 of the feed line pressure.

Q: How much water can I get each day from an RO system?

A: Most reverse osmosis tanks are 15 inches tall and 12 inches in width. An RO unit can operate with water pressure in the range of 40-100 PSIG and produce 10-75 gallons or 45-340 liters per day. Of course, this may differ according to the abilities of your system. Before deciding on a solution, make sure you know what kind of water you need to filter and how much of it is necessary each day.

Q: How noisy is a reverse osmosis system?

A: Most of the time, these units operate with little to no noise. But, you will hear a gurgling sound while the waste concentrate flows into the drain and away from the RO membrane.
Any other noise that you may hear should be a cause for concern. If you hear something like a hissing sound, you will need to get in touch with a service company because there might be pressures problems in the system.

Q: How much electricity do I need for reverse osmosis?

A: None at all, to be honest. A home unit works with the water pressure from your plumbing, so it doesn’t require any electricity. When it comes to larger solutions meant for industrial or commercial use, you will need to use power. These bigger systems use special pumps to push water through the filters and membranes.

Q: What’s the difference between bottled and RO water?

A: In our experience, a majority of people like water filtered with reverse osmosis more than the bottled kind. With the use of carbon filters, you won’t have to ingest chloramines, chlorine, pesticides, arsenic, herbicides, and other contaminants. When these pollutants get removed, it makes your water safer and improves its taste. In contrast, distilled and bottled water can taste off or flat. Reverse osmosis doesn’t remove all minerals, so it produces a better taste. Furthermore, filtered water is more cost effective than the bottled kind and has less of an impact on the environment. After all, all that plastic packaging has to end up somewhere.

Q: How long can my reverse osmosis system work?

A: To improve the lifespan of your RO unit, you should always perform regular maintenance. If service is often done and done correctly, you can expect to get years and years out of most systems. At the same time, filters have to be changed to prevent contaminants entering the finished product.

A general rule is that sediment, polishing and carbon filters last about one year, and the RO membrane two years. Note that these are only general recommendations which might not apply to every situation. Depending on the quality of your tap water and usage, you might need to change filters less or more often. Finally, tubes or the storage tank might need replacement. Other than that, an osmosis system doesn’t require special maintenance and tend to work for years.

Q: Is an RO system worth the money?

A: If you look at the cost to buy and install one, you might be reluctant to spend the money. But, if you calculate how much it costs to run it per day, you will realize how much you can save.

These systems can cost 30 cents or under to operate and own if you have four people in your household. Many Americans spend up to 100$ each year on bottled water (or 400$ for four people). An RO system ends up being a much better option since it costs only around 100$ per year. But those are just the benefits regarding money. With reverse osmosis, you will preserve your health as well. You won’t be exposed to harmful pesticides, herbicides, arsenic, and other contaminants anymore. With all things considered, an RO system is worth it in many cases.

Q: Does reverse osmosis remove healthy minerals?

A: The water in every city differs to some extent. Some tap water can have more minerals which change its smell and taste. When you use filtering, RO separates most of these minerals and makes water more palatable. Since the mineral content is in an inorganic state, our digestive system cannot absorb it. That’s why removing these minerals doesn’t make water filtered with reverse osmosis unhealthy. Your primary source of nutrients and minerals is food, not water.