April 14, 2018

11 Best Reverse Osmosis Water Filter Reviews and Comparisons [2019]

Best Reverse Osmosis Water Filter Reviews 2019

What is so special about reverse osmosis (RO) that makes it the highest recommended water treatment method for your home? Is it a standalone filter or does it work as part of a system to deliver the highest quality drinking water? These questions and more is exactly what we try to answer, so lets get into some of the best reverse osmosis water filter reviews.

The following reverse osmosis water filter reviews contain different approaches to cleaning water, all of them centered on a reverse osmosis membrane. We are looking at not only the top brands but also the most efficient products and the most economical.

Reverse osmosis is a slow filtration process since it takes time to push water through the RO membrane, which is why most if not all home RO systems are installed at the point of use instead of the water main. You will find that many of these reverse osmosis reviews are under-sink RO system reviews.

To better compare RO water systems and choose the right design for your home or office we have also laid out a detailed buyer’s guide. That will explain the most important features to look for in an RO system. We will also provide information on what it usually takes to install and maintain an RO system in working order, so that you can get the most out of it.

Product

Image

Model

Price

Flow Rate

(GPD)

Contaminants Removed

Pros

Cons

Home Master TMAFC

$$

50

- Chlorine

- Heavy metals

- Pharmaceuticals 

- Easy to maintain

- 7 filtration stages

- Sturdy


- A bit complicated to install

APEC Top Tier 5-Stage ROES-50

$

50

- Arsenic

- Lead

- Chlorine

- Fluoride

- Over 1000 viruses removed

- Affordable

- Great tasting water

- 5 filtration stages 

- Not easy to follow installation guidelines 

Home Master TMHP HydroPerfection

$$$

75

- Sediment

- Iron

- Heavy metals 

- Other contaminants 

- Re-mineralizes the water

- 9 filtration stages 

- Quite expensive

iSpring RCC7

$$

50

- Arsenic

- Asbestos

- Chlorine

- Over 1000 contaminants

- Easy to install 

- Replacement filters are inexpensive 

- Design could have been built more sturdily 

APEC Ultimate-series RO-90

$$$

90

- Chlorine

- Heavy metals

- Arsenic

- Over 1000 contaminants

- Installation is easy

- System is very quiet

- Great tasting water

- Fairly costly 

iSpring RCC7AK

$$

75

- Asbestos

- Arsenic

- Bacteria

- Hormones

- Over 1000 contaminants

- Sturdy design and components 

- O-ring is a little flimsy

Express Water RO5DX

$

50

- Pharmaceuticals 

- Lead

- Over 1000 contaminants

- Excellent customer support


- Complicated installation instructions 

Brondell H2O+

$$$

55

- Chloramines

- Barium

- Radium

- Copper and many other contaminates 

- No hard water taste 

- Water wastage is reduced

- Quite costly 

iSpring RCC1UP

$$$

100

- Arsenic

- Bacteria

- Calcium

- Over 1000 contaminants

- Sturdy housing for the filters

- Large capacity 

- Reduces scale build up 

- Expensive

APEC Portable Countertop

$$

90

- Viruses

- Over 1000 contaminants 

- Perfect for apartments or motorhomes

- Quick to install

- Large capacity 

- Only has 4 filter stages 

iSpring RCS5T

$$$$

500

- Pesticides

- THMs

- PFOS

- Sulfur

- Pathogens

- More than 1000 contaminants

- Very large flow rate 

- Easy to replace filters 

- Very expensive 

Best Reverse Osmosis Water Filter Reviews

Home Master TMAFC Artesian Undersink Reverse Osmosis Water Filter System

The Artesian Full Contact RO system by Home Master features an easy-to-use high flow rate design. This pre-assembled model comes with seven stages of filtration and water enrichment that guarantee the production of high quality drinking water.

Features

Reverse osmosis can remove nearly all minerals from the water, thus lowering the pH of the filtered water which can leave an unpleasant acidic taste. The Home Master Artesian Full Contact addresses this issue by adding calcium and magnesium after the filtering process. By balancing the mineral concentration, the water becomes tastier and even healthier.

This model is also faster than others in its category. By faster, we mean it allows a higher water flow rate, almost double that of its competitors. This means that although it is a 50 gallon per day (GPD) RO system it can actually provide sufficient water for a larger household.

The filters are not your traditional cartridges housed in containers. The filters in the Home Master TMAFC Artesian are fully disposable meaning there’s no twisting, turning and scrubbing the casings involved during maintenance. You simply remove the entire cartridge and replace it with a new one.

A great feature of the model is the use of a catalytic carbon filtration unit. This is superior in dealing with chlorine by-products and other harmful chemicals that can damage the RO membrane. It speaks volumes to the longevity of the whole system.


Pros

  • Remineralization treatment stages
  • 7 filtration stages
  • Easy-change filters
  • Catalytic carbon filtration


Cons

  • High water waste rate


Summary

There’s nothing not to like about the Artesian Full Contact RO system by Home Master. The 7-stage filtration and treatment circuit delivers high quality water at impressive speed. The simple installation and filter maintenance also help put it at the top of most under-sink RO system reviews.


APEC Top Tier 5-Stage Ultra Safe Reverse Osmosis Drinking Water Filter System

The APEC Essence-series ROES-50 uses a highly effective pre-treatment line of filters to increase the longevity of its RO membrane. It can provide you with many years of clear and clean drinking water. It also doesn’t take up much space under the sink.

Features

This model runs the water through a 5-stage filtering system before it goes in the storage tank, ready for your glass. The filtration process starts off with a sediment filter to block out dust and rust. This is followed by two separate carbon block filters that remove any chemicals that could be damaging to the RO membrane.

The high rejection RO membrane can trap 99% of potential contaminants which include lead, fluoride, arsenic, and other heavy metals. Another carbon filter, a coconut carbon filter, is used in the final stage of treatment. This last filtration step takes care of any residual impurities that cause bad taste and odor.

The installation process is straightforward which makes it a prime candidate for a DIY project. The instruction manual provides all the details and the online tutorial found on the APEC Top Tier 5-Stage website is very easy to follow. The maintenance is no problem as the entire unit is quite small and all individual filter casings are easy to reach.


Pros

  • 5-stage filtration system
  • long-life block filters
  • Easy installation and maintenance
  • Lifetime technical support


Cons

  • Higher than average pressure drop
  • No remineralization treatment


Summary

What more can you ask for than an easy installation and multiple filtering stages that produce high quality drinking water? If you’re looking for durability and great customer support, you’ve got that too with one of the top manufacturers in APEC.


Home Master TMHP HydroPerfection Under sink Reverse Osmosis Water Filter System

The HydroPerfection TMHP is Home Master’s top-of-the-line model that can more than hold its own no matter how you compare RO water systems. It uses advanced pre-treatment and post-treatment purification methods to deliver the best drinking water for residential homes. The addition of the UV filter makes it one of the most complete under-sink filtration units available.

Features

The HydroPerfection achieves a 1:1 waste water to clean water ratio – this is extremely efficient for RO water filtration systems which are notorious for high water waste rate. It does this while also having an output of 75 GPD, assisted by a permeate water pump.

In addition to the traditional sediment and carbon block filters, the Home Master TMHP HydroPerfection has a remineralization treatment unit and a UV filter. The UV light sanitization is instant and unmatched by other methods.

Much like the Home Master Artesian Full Contact, this modular design is a breeze to install even if you lack basic plumbing skills. The detailed manual and instructional videos provide enough information for you to be your own plumber and have this RO system ready to go in under an hour.

The maintenance is smooth because of the disposable filters. There’s no more need to change cartridges and clean casings. You can just throw them out entirely and put new ones on. Because of the efficient pre-treatment process, the RO membrane and UV filter are more effective and will last longer.


Pros

  • Great tasting water
  • UV filter destroys bacteria and other microorganisms
  • Built-in water pump for higher flow rate
  • Adds minerals post-treatment to balance pH levels
  • Increased durability
  • Easy to install and maintain


Cons

  • Higher end price tag


Summary

Although the HydroPerfection doesn’t come cheap, it is easily in the running for the best reverse osmosis water filter. It reduces waste water to a 1:1 ratio, it has medium-to-high GPD rating, and it sanitizes water with a UV light. It’s hard to find a better structured design with such efficient patented technology.


iSpring RCC7 High Capacity Under Sink 5-Stage Reverse Osmosis Drinking Water Filtration System

The RCC7 by iSpring is another juggernaut RO system of almost unmatched quality and efficiency, and it does at a highly competitive price point. Multiple pre-filters are used along with a multi-layered RO membrane to provide crystal-clear and tasty drinking water.

Features

There’s more to the pre-treatment the RCC7 offers than meets the eye. This RO system also has a water softening feature which makes it perfect for anyone faced with hard water problems.

The waste water ratio varies between 5:1 and 2:1. These are decent numbers for an RO system and it’s easy to stay in the 2:1 range if you can supply good water pressure. While it doesn’t have the best ratio it does offer one of the best flow rates of up to 75 gallons per day.

The combination of pre-filtration, RO filtering, and a granular activated carbon filter ensure that most harmful contaminants don’t make their way into your drinking water. However, at this price point, you can’t expect the iSpring RCC7 to offer post-treatment options such as remineralization or UV sanitation.


Pros

  • Budget-friendly
  • 5 filtration stages
  • Water softener
  • Includes all the tools and accessories for installation
  • Useful tutorial videos


Cons

  • Slightly acidic taste
  • Unpredictable waste water ratio


Summary

The RCC7 from iSpring is a strong competitor on the RO systems market. It delivers high quality drinking water and maintains very low waste water ratios. The built-in water softening feature makes it more versatile than other similarly priced models. Whatever it lacks in post-treatment options it makes up for with an attractive price tag.


APEC Top Tier Supreme Certified Reverse Osmosis Drinking Water Filter System

No reverse osmosis water filtration system review is complete without the popular APEC Top Tier Supreme. The APEC Ultimate-series RO-90 is a high capacity, high flow reverse osmosis system. It uses multiple filtering stages to help the RO membrane work at maximum efficiency, removing 99% of all contaminants.

Features

The pre-filtration is a 5-micron sediment filter for rust, dust and similar particles. This is followed by two carbon filters that remove most organic and chemical contaminants that may damage the RO membrane. There is no post-treatment remineralization process so the pH level may get low enough to turn the water slightly acidic, but that’s actually the clean taste that many people associate with the best reserve osmosis water filter.

The best feature of the Ultimate RO-90 is its 90 GPD capacity. Of course, this is measured at a standard 60 psi and 77 degrees Fahrenheit. It could drop to as low as 75 GPD if the pressure is not lower.

As most reverse osmosis reviews will tell you, a higher capacity offers more utility. A 90 GPD RO system can do more than just provide drinking water from the faucet. You can hook it up to other appliances such as ice makers to have the clearest ice cubes. RO treated water also lasts longer when frozen so you’re in for a real treat.


Pros

  • WQA Gold Seal certified
  • Increased capacity of 90 GPD
  • High quality materials used for filters and filter casings
  • Detailed installation instructions
  • Easy to maintain
  • Extended-life filters


Cons

  • No remineralization treatment despite the higher price tag


Summary

If you care more about GPD and less about post-filtration treatments then the APEC Ultimate RO-90 might just be the system for you. It is easy to maintain due to the use of premium materials and larger cartridge sizes which make them last longer. The above average water flow rate gives you the choice of connecting it to your appliances, if you so wish.


iSpring RCC7AK Reverse Osmosis Drinking Water Filtration System with Alkaline Remineralization Filter

The iSpring RCC7AK is an efficient 6-stage RO water filtration system with multiple layers of protection before and after the RO membrane. It is easy to set up as a DIY project and the flow rate is up to 75 GPD for your household use.

Features

This medium-to-high output RO system is relatively easy to install if you follow the manual instructions or the online videos. Depending on your plumbing and existing sink configuration, very few extra tools are required.

The RO membrane is a proprietary thin film that can filter down to 0.0001 micron. As long as it works at maximum efficiency you should always have clean and proper tasting water to drink. We say tasty because the alkaline remineralization filter takes care of any pH imbalance that affects acidity and taste.

The sediment filter is housed in the same reinforced transparent casing as other models. This allows you to see whenever it is clogged or shows signs of dirty. If you are relying on well water then the sediment filter will require more frequent replacement.


Pros

  • 6-stage filtering system
  • 75 GPD
  • Filters downs to 0.0001 micron
  • pH balance post-treatment
  • Easy to install and maintain


Cons

  • Lower than average filter replacement intervals


Summary

The RCC7AK by iSpring can supply clean and tasty drinking water to an entire family. Its high capacity and easy-to-install design make it a good choice. It is relatively affordable and offers plenty of post-filtration treatment options for its price range. Perfect taste and safety aren’t always a package deal with some of the other RO systems out there.


Express Water RO5DX 5-Stage Under sink Reverse Osmosis Drinking Water Filtration System

The RO5DX by Express Water is a 5-stage RO water filtration system perfect for small homes. It uses a post-treatment carbon inline filter to enhance the taste and odor of the water. It is one of the best designs Express Water RO5DX has to offer yet available at a very competitive price.

Features

Before the water reaches the RO membrane, it passes through a sediment filter, a granular activated carbon filter, and a carbon block filter. This makes it so the water contains as few chemicals, dust particles and particles as possible before going through the reverse osmosis membrane.

While it doesn’t have a pH post-treatment option, it does feature the carbon inline filter to enhance the taste. This also helps maintain the storage tank for a longer time.

Perhaps the most interesting feature of this budget-friendly design from Express Water is that it comes with a set of replacement filters. Since the maintenance is easy enough to perform you should have no problem noticing when it’s time to change. The signs are decreased pressure or a decline in taste.


Pros

  • Easy to install
  • 5-stage filtration system
  • Post carbon inline filter for improving taste
  • Comes with a full set of replacement filters (2 sets total)
  • High quality steel tank
  • Competitive price


Cons

  • No pH balance treatment
  • Doesn’t handle hard water too well


Summary

Considering its price, the RO5DX delivers more than we expected. We can overlook the lack of a pH treatment in favor of the 0.8 gallons per minute flow rate that the included faucet can deliver. However, this is of course not the actual flow rate through RO membrane (0.8 GPM is 1152 GPD which is astronomical). As soon as you use up the water in the storage tank, the faucet will stop – but you can enjoy 0.8 GPM in the meantime if you use the water judiciously.


Brondell H2O+ Circle Reverse Osmosis Water Filter System

The Brodell H2O+ Circle has a very futuristic hi-tech design. It’s not just for show as it completely hides the filters from plain sight while still allowing easy access from the back. It also uses an innovative system to maintain the water flow at a constant level without the use of electric pump.

Features

The patented Smart Valve feature is highly efficient when it comes to flushing the membrane and maintaining the water flow. Because it reduces back pressure, it allows the Circle to be one of the most efficient RO water filters.

The waste water ratio is between 2.4:1 and 2.1:1 gallons, which is miniscule for an RO water filtration system. The refill rate of the Circle water storage tank is the fastest out of all non-electric designs. It also manages to compete with some models with built-in pump, which is more than impressive.

While it doesn’t have the highest water flow rate it has the most consistent one. The design is also something very few other RO systems have, if any. The sleek black finish looks like a high tech computer server. It’s surprising that the maintenance is so easy given that the filters are covered.


Pros

  • Futuristic design
  • Constant flow rate
  • 4-stage filtering system
  • Low waste water ratio
  • Quiet
  • Filter change LED indicator on the faucet


Cons

  • While constant, the water flow is not that impressive
  • Small water storage tank


Summary

The Brondell Circle is in an interesting place. It uses innovative patented technology to deal with the inconsistencies of water flow rate and yet it lacks post-treatment features and storage capacity. Somehow it manages to overcome those drawbacks with a unique design and quiet operation and of course, high quality drinking water.


iSpring RCC1UP 6-Stage Maximum Performance Under-Sink Reverse Osmosis Drinking Water Filtration System

The RCG1UP 6-stage RO system by iSpring is one of the most efficient bacteria-killing systems on the market. It comes with a UV filter already attached that turns on and off whenever it’s needed. To top it all off, it has a very low waste water ratio and quite the high flow rate.

Features

The RO membrane can handle 100 GPD. It’s clearly superior to most home RO systems. The standard pre-filters are top-of-the-line and make sure no rust, organic particles or harmful chemicals reach the RO membrane.

The cherry on top is the 11W UV light filter. This applies instant treatment on the water by killing unwanted bacteria, microbes and many viruses commonly found in municipal and well water. The UV light only works when water is flowing and shuts off when there’s nothing to do. This increases the life of the bulb.

The booster pump is almost silent but don’t let that fool you. When this pump kicks in you won’t have to worry about low incoming water pressure from your main line. The booster pump provides the necessary force for water to go through the RO membrane at the high clip of 100 GPD. This also does wonders at maintaining a low waste water ratio.


Pros

  • Pre-installed low-noise booster pump
  • UV light filter with on/off sensor
  • 6-stage filtering system
  • High capacity of 100 gallons per day


Cons

  • Priced at the higher end


Summary

This may not be the cheapest option but it can outperform more expensive models. It has everything you need for the highest quality drinking water from pre-filtration to post-RO UV treatment and pH balancing. It also has one of the highest GPD ratings on our list.


APEC Portable Countertop Reverse Osmosis Water Filter System, Installation-Free

You may not always need a permanent solution when it comes to RO systems. If you don’t want to bother with installing a large tank under your kitchen sink then the APEC Portable Countertop Reverse Osmosis is for you. It has a standard pre-filtration line and a very high GPD RO membrane.

Features

The most important feature of any countertop RO system is the fact that you can take it with you whenever you like. As long as there’s a standard faucet waiting for you, you just connect it and start drinking. It only takes minutes and most times no tools are required.

You don’t always need large and bulky systems to benefit from a multi-stage filtration system. The APEC RO-CTOP is the case in point. The standard sediment and carbon filters are used to keep the RO membrane working at optimum levels.

You can rarely ask for more than a 90 GPD capacity on such a small unit. The variation in water pressure needed is very good for a small countertop RO system, though this is to be expected considering it’s by a top manufacturer.


Pros

  • 90 GPD rating
  • 4-stage filtering system
  • Very fast installation
  • Portable RO system


Cons

  • Not an aesthetically pleasing design
  • Only works on standard faucets
  • Not too budget-friendly


Summary

Sure, it takes up some counter space and looks out of place but you can cover it up with a stylish cloth. This small unit is working nearly anywhere. You can take it on the road or keep it in your permanent home. Unless you’re extra picky about how the water tastes, this RO system might just be your best friend for years to come.


iSpring RCS5T 500 GPD Reverse Osmosis Water Filter System

They rarely come bigger and meaner than the RCS5T from iSpring. This won’t fit under just any kitchen sink. It looks more like a whole house RO system and has the capacity to back up the claim as well.

Features

The 500 GPD capacity is staggering considering it’s nearly 10 times as high as regular RO systems at only two times the price. Sure the flow rate will vary with pressure and temperature, and for this model it can go down by as much as 75%. That’s still a massive flow rate no matter how you look at it.

The RCS5T makes use of a dual-flow RO membrane to maintain a consistent flow and ultra-low waste water ratio of 1:1. It also uses five filtration stages in total to provide 99% clean water. It has the standard pre-filters of sediment, granular activated carbon and carbon block, as well as a post carbon filter.

There is one piece of equipment missing from this massive system. The RCS5T comes without a tank, but you don’t really need one since the membrane works fast enough if you can supply the water pressure. Per the manufacturer’s instructions, you can add one with a capacity between 200 and 500 gallons. You might also want a separate delivery pump too.


Pros

  • Highest GPD on our list
  • Commercial grade 5-stage filtering system
  • Consistent flow
  • 1:1 drain ration


Cons

  • Additional costs if you want to add storage tank and pump
  • No pH treatment


Summary

We’ll overlook the tankless design of the iSpring RCS5T 500 because of its sheer power and capacity. The dual-flow RO membrane maintains a great flow rate and keeps waste water ratio to a constant 1:1 under perfect conditions. This is not something you want for your studio or two-bedroom apartment. This commercial-grade system is for large families, restaurants and offices.


Buying Guide

As promised, here’s the buyer’s guide following the reverse osmosis water filtration system reviews.

There are many reasons why you should want to purchase an RO system. There are also plenty of factors involved in what makes a particular system better for you, or better overall. Before we get there, you should familiarize yourself with some commonly used terms and features and understand how much of an impact they should have on your decision.

Total Dissolved Solids (TDS)

TDS refers to some organic matters but mostly it stands for calcium, sodium, chlorides, sulfates and other inorganic salts. The TDS value on RO systems is an indicator of efficiency. Of course, no matter how good an RO system is, it won’t achieve optimum TDS levels (500mg/L) if the pre-filtered water is too contaminated or hard for the RO membrane.

Water Output

Water output values are often given based on tests performed under perfect conditions. This usually means the water is at 77 degrees F and 60 psi. You should always take water output values as a guideline and expect a lower output than advertised. Based on the efficiency of the RO system, you may experience up to a 50% output loss.

Air Gap Faucet

Why is this so important? It really isn’t. This is one of those fancy features that you don’t have to look for when buying an RO system. Regular RO system faucets have their own siphon breaker installed and some believe it is just as effective as an air gap.

Air gap faucets use an air pocket to prevent waste water from backing into your RO system. This siphon breaker is very effective but it almost always requires professional help when installing the system. There are different diameter holes needed for the pipes and for the faucet. It takes a long while to install and you will be charged more for the installation.

PH Levels

Reverse osmosis will remove minerals and therefore lower the pH values in the permeate water. Depending on how high a value your pre-filtered water has, this post-treatment decrease can cause the water to have an acidic taste. While there is nothing wrong with that, it may not tickle the taste bud of some people. If that is the case, there are RO systems with post-treatment in place to add minerals to the water to raise the pH.


Factors to Consider When Buying a Reverse-Osmosis System

There’s just so much to take into consideration when it comes to buying an RO system. Some of the best reverse osmosis water filter reviews agree that a few factors are often overlooked in favor of fancy terminology and numbers listed on the packaging. Let’s take a look at what should really be at the top of your list.

Price

The main concern of most customers is always the cost. While it is true that there are some very budget-friendly RO systems out there, going the budget route might not always be the best idea.

When you pay extra for an RO system, you pay for technology and higher quality materials. The materials are what make the model durable and worth it as an investment. It is especially important with under-counter RO systems since they are permanent solutions.

When you pay more for technology you are usually getting less waste water. While it’s not always true that an expensive RO system cleans the water better, in most cases it will have better water management. You can save a lot of money in the long run by wasting no more than 1-2 gallons for every gallon of permeate water.

Capacity

The capacity of the water tank and how many gallons per day the RO system can process is a major factor. If you have a large family or want to connect the RO system to other appliances like ice makers, you want a high capacity of around 100 gallons. Keep in mind that most RO systems aren’t 100% efficient and you may end up getting less than what’s written on the label.

You can choose a 50 GPD model for a small home or if you’re single. This category of RO systems provide all the drinking water you need. If you’re looking for more use with appliances, even though not many people use it, go for an 80 GPD model. It should provide enough flow rate and water pressure.

Filtering Stages

You might think that all RO systems come with the proper pre-treatment methods, but you would be wrong. Just because there are three sediment and carbon pre-filters installed before the RO membrane does not mean you have the perfect system.

Always check for the quality of the materials used. Not only that, but make sure that the RO system you’re looking at can handle the water in your house. Always keep that water analysis handy when you’re buying a water filter system of any kind.

In some cases, you may not need high-end additional filtering stages in your RO system. For residential use, you don’t always need a 7-stage RO filtering system. You may not even need a 4 or 5-stage RO system if you already have a good whole house filtering system.

Water Waste

How much water your RO system wastes is highly important. Some units waste up to 24 gallons of water to produce one clean gallon. Paying more upfront for new technology will help keep your bills at a more reasonable rate.

Another factor you might want to consider when it comes to waste water is how it is dealt with. Not all RO systems dispose of the waste. If the system you have your eye on recycles or dispenses waste water to other appliances, think long and hard if that’s something you want. Most of the contaminants that are bad for you are also bad for your boiler, dishwasher, washing machine and other appliances.

Installation and Ease of Use

These two factors should not be first on your list of priorities. The installation process can be done by customers most of the time. Whenever that’s not an option, the cost of calling a professional is well worth it if you want the best water treatment system.

Using an RO system on a daily basis requires no skills or knowledge. It’s as easy as using any other faucet. Maintenance is also not as complicated as advertised sometimes. Changing the filters on the pre-filtration units is easy and cleaning the RO membrane is usually done by a specialized cleaning process. You rarely need any tools to get in and out of the casings as most times it’s as easy as twisting a cap – if special openers are needed, they will be included.


How Reverse Osmosis Works

Water that undergoes reverse osmosis treatment does so in five stages. For the sake of this discussion, we will exclude any pre-filtration treatments that happen before the reverse osmosis stage.

In the first stage, the water enters the system and gets fed to the pump. The second stage involves the pump increasing the pressure of the water to force it through the RO membrane. In the third stage the smaller water molecules get separated from unwanted salts and other contaminants.

The final two stages occur almost simultaneously. As the permeate water with a low concentration of salts gets pushed towards the storage tank, the waste water stream gets pushed through the disposal tube or pipe.

The water that makes it through the RO membrane can have up to 99% of salts removed from it. The rejected water is pushed away by cross filtration and ends up in your main drain pipe.

Ok. That’s how the system works but what exactly does it remove? The process of reverse osmosis is able to remove a wide variety of water contaminants. RO membranes that function properly are able to reject particles and contaminants with molecular weights of over 200. This includes some bacteria, microbes, colloids, and salts.

Because of the deionization process, most contaminants with high ionic charges will not get past the RO membrane. This is why it is more efficient at removing calcium than sodium. For the same reason, the permeate water will have a lower pH level than usual.

Here is a video that demonstrates the reverse osmosis process:


Types of Reverse-Osmosis Systems

There are two main choices when it comes to RO systems. You can go for a countertop model or an under counter model. There are of course some differences in terms of efficiency, convenience, and price.

Countertop RO Systems (Freestanding)

Countertop RO systems are not as efficient but they are very convenient for people that travel a lot. They are also a great choice for people that rent. They don’t have a complicated installation process and can be moved from one home to another with ease.

Although these are designed to stay on your counter, they do take up some space. They are clearly not as big as under-counter RO systems but may still inconvenience you. They are also not visually appealing so they might not be for you if you care about décor.

Under Counter RO Systems

Your typical under-counter RO system is the most popular option. It takes up plenty of space but it goes under the sink so at least it’s out of sight. It has a lengthy installation process that may often require professional help. Another drawback is the potential of massive waste water production.

Luckily the pros outweigh the cons with under-counter RO systems. New models have great waste reduction technology and most efficient may not waste more than one gallon per gallon of permeate water. Although they take longer to install, the end result is worth it since they can filter and store larger quantities of water. Not only that, but they also do it faster than countertop RO systems.


Stages of Filtration

Most RO systems come with multiple stages of filtration not only to get the most out of the RO membrane but also to protect it. Microorganism growth in the RO membrane is a common cause for it losing efficiency. The same can be said about chlorine and chlorine by-products passing through the RO membrane.

Because this final stage in the RO systems uses such a delicate thin layer of membrane, there are many precautions taken. The most common pre-filtration stages include a sediment filter, a granular activated carbon filter and a carbon block filter, in that order.

The sediment filter removes dust, rust and other large sediments from the water. The granular carbon filter takes care of organic contaminants. The carbon block filter removes chlorine and chlorine by-products as well as other chemicals that are damaging to the RO membrane.

It is rare for RO systems to come with more than these three pre-filtration stages but not uncommon. Furthermore, for some households additional pre-treatment methods may be needed. If the water quality is very poor, you might need to install a whole house filtration system or at least more point-of-use filters upstream of your RO system.

best reverse osmosis water filter reviews

Installation and Maintenance of RO Filter Systems

Installing an RO filter system is not too difficult and can be done without professional assistance if certain conditions are met. First of all, you should have your water analyzed before purchasing a water filter system. As most manufacturers will point out, using an ineffective RO system due to the wrong type of water won’t always entitle you to a refund.

You should also consider your existing sink. Most RO systems come with their own faucets so it would be easier on you if you have an additional hole in your sink for that. If not, you may need to change your sink or start cutting a hole for the RO system’s faucet. If you lack the tools to do this, you will need to call a professional.

Another common installation issue comes up when it’s time to connect the waste water tube to your main drain pipe. Not all kitchen sinks come with a drain pipe that has an extra orifice. If that is the case, you will need to start drilling. Make sure to measure properly. You could also wrap some tape around the drill tip to make sure you don’t drill all the way through both sides.

The rest of the installation is actually easier than it seems. You should not be intimidated by all the tubes and cables as everything tends to be color-coded. Either that or they have clear markings as to which goes where. Be sure that before you do anything, your main water line is turned off and excess water from the drain pipe is removed to make it easier should drilling be necessary.

After everything is set up according to the instructions manual, take your time to run a couple of cycles through before using the water for drinking. It will depend on what the manufacturer recommends and how long it takes for the tank to fill up. The process of filtering and emptying the storage tank could be anywhere between one and three hours.

Of course, installing the RO system is not the last time you’ll have to deal with the unit. As all filtering systems go, whether they are point of entry or point of use, the filter cartridges will need changing. Carbon and sediment filters may require a replacement every six months. If you have high quality ones and the water coming in is not too bad they might last you a year.

Under ideal conditions, an RO membrane can hold up for two years. You can easily notice when your RO membrane deteriorates. If the quality of the water simply drops then it is probably due to a high concentration of chlorine in the water. If your RO faucet doesn’t offer the same pressure, it is likely due to mechanical damage.

Just because RO membranes last up to two years doesn’t mean they don’t need the occasional cleaning. Some recommend that you clean the RO membrane up to four times a year. We find that it is generally enough to wait until the water pressure drops. If this happens before the two-year mark, you may want to remove the membrane and take it to a cleaning service.

 You could do this at home, but the investment in high pH cleaners and cleaning equipment is not worth it. To effectively clean an RO membrane, you need more than just a good chemical mix. You need to control the water flow, temperature and much more, which is why a professional service is highly recommended.

An additional maintenance treatment could help maintain the efficiency and durability of your membrane. Using a water softener is recommended when your water analysis shows high grain per gallon (GPG). If higher than 7, you may want to look for a softener immediately.


Conclusion 

Reverse osmosis (RO) filters out many contaminants from water by forcing the water through a semi-permeable membrane at high pressure. This process causes the water to deionize. The reason it is called RO is because unlike naturally occurring osmosis you need to push the water through the membrane with enough force.

You can think of the RO membrane as a screen door. It will let all the air in but it won’t let flies, mosquitoes and other such critters enter your home. A similar effect is obtained when sifting flour or when using a strainer to separate unwanted bits of meat and veggies from your gravy.

The same technique is use in RO systems with one addition. Pressure is added to push water through the membrane and have it catch unwanted particles. Without forcing the water through the membrane it won’t go through at an efficient rate.

    Lisa Boyle

    I'm Lisa and we founded this website to help you find the latest info and products related to water filters. As a mother of two beautiful kids, my husband and I wanted to make sure we promote a healthy lifestyle and ensure a clean water supply. I have no doubt you want the same for your family. Our team will review various products and offer you guides to help you make your decision easier.

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