Reverse Osmosis (RO) Water Purifier | Advantage & Disadvantage

Reverse osmosis water purifiers are ideal for every household. The idea of water filtration isn’t “new” by any means.

People have been filtering their water anyway since the dawn of humankind. Drinking pure water is one of the essential things to lead a healthy life.

To get the safest and clean water people buy water purifiers. There are so many water purifiers are available in the market or online.

RO Water Purifiers are the most efficient and reliable water purifiers. They can purify higher water with a higher TDS level

History Of RO 

Reverse Osmosis or RO technology was developed in the late 1950s through U.S. Government funding as a possible method of desalinating seawater.

Millions of homes use RO drinking water systems . Even by NASA to ensure the astronauts have clean, safe drinking water even in space.

So why do millions of consumers choose RO drinking water systems for their homes? Let’s explore the detailed functions of RO with its advantage, disadvantages. 

What Is Reverse Osmosis (RO)

Liquids have a natural tendency to move from an area of lower concentration to a higher one when separated by a semipermeable membrane.

The water absorption by the roots of the plants is the best example of osmosis. Reverse osmosis is the exact opposite of osmosis. In this reverse osmosis, the liquid moves from an area of higher concentration to that of a lower one, again through a semipermeable membrane.

This is against their natural behavior. The role of the semipermeable membrane is very essential in Reverse Osmosis. This membrane performs a selective role in the sense that it allows some molecules to pass through when restricting the others depending on their size.

Most of the houses have screen doors that allow air to pass through but deters insects like flies and mosquitoes. The semipermeable membrane is quite the same in many aspects.

The best quality of the semipermeable membrane is that it allows for the flow of liquid in one direction. It is because of the force you exert during reverse osmosis.

Reverse Osmosis is extremely useful for separating pure water from other components. It also helps in the elimination of dissolved solids in water so that you can get pure water to drink.

Let’s see how RO water purifiers work.

The RO Water Purifier Working Process: 

In a normal filtration process, you will notice the collection of impurities on the filter media that you have to discard before reusing it.

This process should be infrequent maintenance. The RO water purifiers basically work on a different concept known as cross filtration.

This concept provides to use of two outlets. One is for the pure water to flow through on the other hand the other outlet caters to the elimination of contaminated water, also known as reject water in industry circles.

The rejected water contains an overwhelming 93% to 95% of impurities. Some people suggest recycling this water back into the filtering machine.

But this process can cause a strain on the machine especially if the concentration of contaminants is high. So you can drain this water out or use it for alternative purposes like washing toilets, floors, etc.

An effective and well-efficient RO system can eliminate 99% of TDS (Total Dissolved Salts), molecules, ions, and also impurities like viruses, bacteria, and pyrogens.

In the normal course, contaminants having a molecular weight in excess of 200 cannot pass through the RO filters.

To keep things in proper perspective, water has a molecular weight of 18. At the same time, the RO filters cannot allow ions of higher valency to pass through.

Now, sodium is a monovalent ion. Therefore, sodium ions pass through the RO filters to make sure they use supplemental filters to eliminate such ions.

RO filters can remove the heavy metal impurities but allow gases like Carbon dioxide (CO2) to pass through.

Hence, you will notice RO treated water as slightly acidic with a pH value below 7. It is a very efficient method to treat groundwater having a high concentration of TDS.

Main Components Of RO Water Purifier

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Sediment Pre-filter:

 The first stage of purification includes pre-sediment filters. Pre-sediment filter not only removes fine and coarse particulate impurities and dirt but also improves the life of the RO/UF membrane resulting in a lower cost of maintenance.

You can separately add this standard feature.

Activated Carbon Pre-filter: 

An activated carbon pre-filter can remove chlorine and organic impurities like harmful pesticides from the water.

Activated carbon pre-filter also can absorb bad odor and taste-causing organic compounds from water.

RO/UF Membranes: 

Water is fed into the RO membrane at high pressure by using an in-built water pump. RO membrane can remove all the hardness, dissolved salts, pesticides, and heavy metals like lead, arsenic, and mercury.

It also removes microbial contaminants like viruses, bacteria, protozoa, and cysts. The UF membrane also works like RO membrane but it cannot remove the dissolved solids.

Some purifiers use both RO and a UF membrane, the output water from both the membranes is together to control the TDS level of purified water.

TDS Controller: 

TDS controller is used to control the TDS level of the output water. RO process not only removes dirt and impurities but also removes essential minerals like Calcium & Magnesium.

TDS controller retains adequate quantities of essential minerals in the purified water by adjusting the ratio of water from RO membrane (low TDS) and UF membrane (normal TDS) when finally mixes up. 

UV Filter

UV filter has a high-intensity UV bulb that is used to kill or inactivate any virus, bacteria, and parasites to deliver safe water.

Carbon Post-filter: 

Carbon Post-filter acts as a polisher and increases the taste of purified water. It also removes any foul smell from water.

Storage Tank:

 This stores the purified water for later use. Be ensured that the storage tank is made of food-grade, non-toxic material.

Some of the high-end water purifiers now feature a stainless steel water storage tank. You should also check the capacity of the storage tank before buying it.


Most of the RO water purifiers features with basic display for purifier on/off, a tank full, etc. Some advanced purifiers also have fault alert, membrane change, UV fail, TDS level indicator, purity indicator, etc.

Types Of RO Purifiers

In India, they are two kinds of RO purifiers available for home purposes in the market or online

  • Undersink RO Purifier
  • Wall Mounted Ro Purifier

Both the Undersink and Wall Mounted RO Purifiers come with a storage tank that stores the Purified Water. Even though there is a power outage the water stored in the tank will also be available for use.

We are going to discuss in brief-

Wall Mounted Reverse Osmosis ( RO )Purifier

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The Wall Mount RO Purifier is the most widely used in India that commonly contains a storage capacity of 5-10 liters.

The only problem with the RO water purifiers is, there is also some water wastage. So, you have to use the wasted water in a proper way; to clean the house and mopping purposes.

Undersink RO Water Purifiers

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The Undersink RO Purifiers are gaining a lot of popularity now as they can be easily fitted under the kitchen sink.

The pure water outlet tap can be fixed next to your kitchen tap and will be very easy to operate.

These types of RO Purifiers are fitted with the Air Pressurized RO Water storage containers that come with a storage capacity of 5 liters.

The Undersink RO Purifiers are acknowledged as the best water purifiers for home purpose as they can be kept under your kitchen sink and doesn’t occupy much space.

The pure water comes from the tap that can be fitted next to your kitchen sink tap.

As it has mentioned earlier, the wastewater can be used for outdoor purposes like gardening.

The Undersink Water Purifier is more suitable than the Wall Mount Ro Purifier. As the under-sink RO Purifier has a pressurized tank, the pure water comes out with more force.


Removal Of Impurities

It can remove 95% – 99% of total dissolved solids (TDS), as well as Chlorine, Fluoride, and other impurities. This percentage can be lower for the lower quality water filters, which is why it is vital to always get a high-quality water filtration system. Sub-par water filtration is nothing more than a total waste of money.

Enhance The Quality Of Water

It will enhance the odor, taste, and appearance of your water. By removing most types of water contaminants, Reverse Osmosis filters fantastically improve the taste of water. Particularly chemicals such as Fluoride and Chlorine, which are purposely added to tap water to offer a significant amount of water filtration themselves, can contain unpleasant odor and taste. So, as their addition to our tap water is justified, filtering them, in turn, is a great way to transform your drinking water into something truly delicious as well as safe also. 

Encourages To Drink More Water

It encourages people to drink more water. It is a statistical fact that families start to consume more water if they get a good water filtration system like Reverse Osmosis. This is for the fact that their water is finally delicious and healthy, which encourages people to consume it instead of taking for bottled water or other beverages. This is vital for our health because most people drink less water than their bodies demand.

By encouraging people to drink this water, Reverse Osmosis filters also have a huge effect on our environment. This is because as they encourage us to use less bottled water, which, in turn, is one of the biggest sources of plastic pollution today.

Increase The Taste Of Food

It increases the taste of your food as well. Since we cook with tap water, a Reverse Osmosis water filter will also significantly improve the taste of your prepared food. All high-quality restaurants are also using Reverse Osmosis water filters in their kitchens.

Energy Efficient

The Reverse Osmosis filtration system is basically fully automated. Once it is installed, a countertop or under sink RO water filter system is fully automated, aside from periodically replacing the filter cartridges themselves.

Reverse Osmosis water filters are very energy efficient because they require no electric power source to function.


Prone To Clogging

Prone to clogging is one of the few issues with Reverse Osmosis water filtration systems. The tiny pores in the semipermeable membrane of a Reverse Osmosis water filter can get easily clogged if the whole system is not properly maintained.

To avoid this you have to follow the system manual and service guidelines of your RO water filter. This is also the reason why a lot of Reverse Osmosis water filtration systems come with carbon or sediment pre-filters is that to assist the Reverse Osmosis semipermeable membrane and help to reduce the likelihood of it clogging.

Filtration Takes More Time

The filtration process takes some time. Reverse Osmosis is not a speedy process and operates by having the water pressure push the tap water through the spores of the semipermeable membrane.

This slows the water flow, that’s why Reverse Osmosis filtration systems have water tanks where filtered water is stored for your convenience. If you need a large amount of filtered water, a water tank might not be enough and you have to be forced to wait for it to be refilled.

Replacement Of Filter Cartridges

It requires the replacement of filter cartridges. The maintenance of a Reverse Osmosis water filter might be quite easy, but it’s not nil.

You still need to replace the water filters and the semipermeable membrane by specific periods and that can be annoying.

Removal Of Beneficial Minerals

The research suggests that beneficial minerals are also removed during the filtration process. Unfortunately, anywhere between 92-99% of the magnesium and calcium generally can be found within the water will be removed – making it increasingly important that these minerals are sought elsewhere.

Facts About Reverse Osmosis Water Filter

Reverse Osmosis water filters are obviously not free, and their filter cartridges need to be purchased and replaced also by time to time.

However, their total price per gallon is exceptional and will be standard family budget-friendly, and also would save you an innumerable amount of money on bottled water.

Depending on the exact type of Reverse Osmosis water filtration system you may prefer, they might have a simpler or more complex installation process.

However, they are all generally very easy to maintain. The only job you need to do in terms of maintenance is to periodically replace the water filter cartridges and the semipermeable membrane of the filter.

Most filters are required to be replaced once every 6 to 12 months, and most semipermeable membranes need to be replaced once every 2 to 3 years.

Along with that, the only other maintenance your RO system requires is cleaning and sterilization once a year.

Frequently Asked Questions 

Is RO water healthy?

 Most RO Purifiers have come with a water softener, which removes hard minerals from the water. TDS Controllers too, help to maintain the essential minerals in the water.
So, RO water is completely safe and healthy to consume and one of the best options to drink.

Which is better? RO or UV?

It is suggested that RO water purifiers are better than UV purifiers. RO gives a high level of purification, on the other hand, the UV purifier is combined with various forms of filtration as UV light can kill bacteria and viruses.
So, RO is better as UV will only drive chemicals to oxidize, which is good for sterilization

Is boiling RO water harmful?

Boiling should not be used when toxic metals, chemicals like lead, mercury, asbestos, pesticides, solvents, etc or nitrates have contaminated the water.
Boiling may concentrate any type of harmful contaminants that cannot vaporize as the relatively pure water vapor boils off.

Can you drink RO wastewater?

Because of the high level of impurities and dissolved solids, this wasted water is not fit for drinking or bathing. But, you can use the RO wastewater in various ways to avoid the overall wastage of water in your home or office.


Now, you know everything about the Reverse Osmosis Water Purifier.

All you have to do is pick the Right RO Purifier that suits your needs. If you have any Queries Regarding Water Purifiers, Post them in the comments section below, and I’ll be happy to answer them.

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