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What is an RO Water Purifier?

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Reverse Osmosis is considered one of the best water purification techniques. If you are wondering why and how, then this article is of a great help.

Here, we have provided a detailed explanation of how RO purification works and what is it more efficient.

You will also find benefits of using an RO water purifier at home. So, let’s us get started.

What Is A Reverse Osmosis Water Purifier?

Ozean 25 Lph Commercial RO Water Purifier

An RO water purifier is an appliance that uses the reverse osmosis process to purify the water. It demineralizes or deionizes the water and removes unwanted particles and harmful contaminants from the water during the water purification process. It further makes the water fit and safe for consumption.

Let us see in detail how the RO purification process takes place.

How Does An RO Process Work In Removing Contaminants?

As mentioned earlier, reverse osmosis is a water filtration and purification method that removes contaminants from the water. In addition to that, the RO improves the quality of water, making it safe for consumption. You can drink the treated water, as it is free from all unwanted molecules and harmful particles.

Here is how the RO purification process takes place:

  • The reverse osmosis purifier consists of a semi-permeable membrane.
  • The unfiltered water is allowed to pass through this membrane with external pressure.
  • During this process, the water flows through the concentrated side of the membrane.
  • As it keeps flowing with external pressure, the contaminants from the water get filtered away.
  • The reverse osmosis membrane traps the contaminants in the water and blocks them.
  • As a result, the uncontaminated and freshwater leaves from one side of the membrane. All the contaminants, including small and large, get blocked on the other side.

Let us have a look at the various contaminants that an RO water purifier removes from your water.

What Contaminants Does The Reverse Osmosis System Remove?

Water mostly consists of contaminants that are harmful to health and cause taste and odour issues. These particles can easily penetrate through streams and rivers, thereby reaching your water lines. No matter how hard your public water suppliers try to remove these contaminants, they still remain in your water.

This is where you can use the reverse osmosis system. Not all filtration or purification systems remove all the contaminants out of the water, but only an RO system can. Below are the contaminants that this reverse osmosis system traps and removes:

Reverse osmosis system can remove

  • Fluoride (85-92%)
  • Lead (95-98%)
  • Chlorine (98%)
  • Pesticides (up to 99%)
  • Nitrates (60-75%)
  • Sulfate (96-98%)
  • Calcium (94-98%)
  • Phosphate (96-98%)
  • Arsenic (92-96%)
  • Nickel (96-98%)
  • Mercury (95-98%)
  • Sodium (85-94%)
  • Barium (95-98%)

What Are The Basic Components Of An RO System?

Although most RO systems look and work similarly and have the same components, the quality of components differs. Below are some of the basic components found in every reverse osmosis system.

  1. Cold Water Line Valve
  2. Pre-filters
  3. Reverse osmosis membrane
  4. Post-filters
  5. Automatic shut off valve
  6. Check valve
  7. Flow restrictor
  8. Storage tank
  9. Faucet
  10. Drain line

Let us look at the significance of each component of the RO system.

1. Cold Water Line Valve:As the name says, this is the valve for connecting to the cold-water

supply line. It comes with a hose for attaching the inlet side of the pre-filter of the RO purifier. Through this filter, the water passes into the RO system.

2. Pre-Filter:The pre-filter is that component that has a connection to the cold-water supply line. Water enters the supply line first and then passes through the pre-filter of the RO system. An RO system may have multiple pre-filters in it, and the most common ones are the sediment and carbon filters.

The primary role of the pre-filter is to protect the RO membranes of the system. They prevent the contaminants, impurities, and other dirt from clogging the system. Furthermore, the carbon filters even help in removing chlorine from the water. This is very harmful to the RO membranes and may damage them.

3. Reverse Osmosis Membrane:The semi-permeable RO membrane is yet another crucial component of the reverse osmosis system. It is like the heart and comes specifically designed for removing a wide variety of contaminants. The water, after it passes through this membrane, enters into a water storage tank. This is where the treated water gets stored.

4. Post filter:This is the final stage where water from the storage tank or reservoir passes through the post filter. It is a carbon filter. After the water comes through this filter, it goes to the RO faucet. In this stage, the filter polishes off the water and effectively removes any unwanted taste and odour remaining in the water.

5. Automatic Shut-Off Valve:The automatic shut-off valve is that component that helps in conserving water. Once the storage tank gets full, this valve shuts off automatically and further stops more water from entering the RO membrane. Additionally, it also blocks the discarded water flow to the drain pipe. Once you start drawing water from the faucet, and the pressure in the tank significantly reduces, the shut-off valve opens again. It allows the drinking water to get inside the water reservoir through the RO membrane. Simultaneously, it will divert the discarded water through the drainpipe.

6. Check Valve:You can locate the check valve on the outlet side of your RO membrane. The primary job of this check valve is to prevent the water from flowing back to the RO membrane from the reservoir. This is an essential component because a backward flow can damage the RO membrane by causing a rupture.

7. Flow Restrictor:As the name says, this component restricts the water flow through the RO membrane. Although these flow controls are available in different styles, the common purpose of all these is to maintain the required flow rate. Additionally, the flow restrictor also helps in maintaining pressure when the water passes into the membrane. This additional pressure is required to deliver treated water in adequate quantities. In absence of this pressure, water gets flowing down through the drain pipe. You can locate this flow control in the drainpipe tubing of your RO system.

8. Storage Tank:The water storage tank or the reservoir is yet another crucial component of the reverse osmosis purifying system. The capacity of a standard tank is two to four gallons of water. When the tank is full, it keeps the water inside pressurized. The size of a regular under-counter RO tank measures about 12 inches and 15 inches respectively in diameter and length.

9. Faucet:Every RO unit features a faucet. These faucets are available in the air gap and non-airgap faucets. While the latter models are more common, the former requires specific plumbing regulations. If you want to complement your kitchen décor, you can choose from the designer faucets available in the market.

10. Drain line:The last vital component of the reverse osmosis system is the drain line. You can find it at the outlet side of the RO membrane that goes to the drain. The purpose of this drain line is to discard the wastewater or contaminated water treated by the RO membrane.

What Is The Working Mechanism Of A Reverse Osmosis Membrane In The Unit?

We all must have now got a complete picture of what reverse osmosis is. RO is a process that removes unwanted and harmful contaminants and impurities from the water by pushing the water molecules through a semipermeable membrane with great pressure. This process traps the contaminants, filters them, and flushes them away from the water. As a result, you are left with clean, safe, healthy, and tasty drinking water. The upside of reverse osmosis is that it can remove up to 99 percent of the wide variety of contaminants like fluoride, chlorine, etc.

The reverse osmosis process generally takes place in four different stages. They are:

  1. Sediment Filter
  2. Carbon Filter
  3. Reverse Osmosis Membrane
  4. Polishing Filter

Let us learn in detail about the filtration process and the various stages below:

1. Sediment Filter

This is the initial stage of the filtration process that uses a sediment filter. Also known as the pre-filter stage, this step traps the sediment, dirt, and silt. It prevents dirt from entering the RO membranes and further protects them from damage caused by sediment.

2. Carbon Filter

The next stage is where the system uses a carbon filter. This filter is specially designed for removing contaminants and harmful particles like chlorine from the water. These particles hamper the functioning and performance of the RO membrane and also decrease their lifespan. The carbon filter further improves the taste and odour of your water.

3. Reverse Osmosis Membrane

The next stage of the reverse osmosis process is the semi-permeable RO membrane. This stage allows water to pass through the membrane and filters any other additional contaminants present in the water.

4. Polishing Filter

The last stage of the RO purifying process is the post filter. It is basically a carbon filter that polishes off the water and effectively removes any unwanted taste and odour remaining in the water. This final stage of the filter ensures that the final output delivered is healthy and safe.

These are the four main filters you will find in the four-stage reverse osmosis system. Apart from these filters, the RO system also has a TDS controller. The primary role of this controller is to retain all the essential natural minerals in the treated water.

Some advanced models of RO water purifiers incorporate the Save Water Technology in them. As per this feature, the RO systems feature a computer-controlled process. As the name says, the save water technology helps recover more than 50% of water as purified water. Consequently, you will have less water wastage, as well. And the best part, you can use this discarded water for several domestic purposes and to water the plants.

Factors Affecting the Performance of a Reverse Osmosis System:

Below are some of the factors affecting the performance of an RO system

  • You need to ensure appropriate pressure from the incoming water. If it is below the required pressure level, the system will fail to operate properly.
  • The temperature of the water also affects the performance of the RO system. Remember that cold water always takes more time to filter than water with a normal temperature.
  • TDS in the tap water is yet another parameter.
  • The quality of the components in the RO system, especially the filters and membranes.

How to Maintain a Reverse Osmosis Drinking Water System?

Any appliance needs regular and proper maintenance to prolong its lifespan. Similarly, you need to maintain your reverse osmosis system, as well to ensure it lasts for many years. Furthermore, it facilitates high-quality drinking water while delivering effective water output. To ensure the same, you will have to follow specific maintenance instructions. Here are some of the RO maintenance tips for your reverse osmosis system.

1. Change Filters

The first instruction to follow is changing the filters as and when needed. The filters and the RO membrane used in the reverse osmosis system will lose their effectiveness over time. Hence, make it a routine to replace them as per the schedule. Remember, this is the most crucial aspect of your RO system.

As mentioned above, the RO membranes and filters get clogged with dirt and impurities. They even get foul. As a result, the effectiveness of your RO system will get hampered, and it will produce less amount of filtered water. To prevent this, you will have to change the filters regularly. You may ask how often should I do it and how will I know that it is the right time to do it. Well, here are the timelines for each kind of filter. Remember that the frequency of replacing the filters is entirely dependent on your usage and the water condition in your locality.

Generally, below is the scheduled timetable for replacing your RO filters:

Type Of Filters Frequency Of Replacement
Pre-filters (Carbon and Sediment Filters) Every six to 12 months
Reverse Osmosis Membrane Once in every two years
Post Filter (GAC polishing filter) Yearly once

2. Sanitize The Entire System

Here is the next crucial step in the reverse osmosis system maintenance routine. You should clean your RO system thoroughly, sanitize it properly and recharge it annually to increase the lifespan. You may ask us when to sanitize the system. We are here to simplify things for you. You can sanitize your RO water purifier every time you change your filters. This would save your time and also keep you on the right maintenance track. You can seek the help of a professional to clean and sanitize your RO purifier. Else, you can change the filters and sanitize the entire purifying system annually.

3. Replace Parts

Here is another essential thing you ought to do without fail – to replace the parts of your reverse osmosis system. The parts of your RO water purifier will wear out after a certain period. You will need to replace those parts regularly to ensure the effectiveness of the purifier. You can find the replacement instructions and recommendations on when and how to do it in the user manual provided.

What Are The Benefits And Limitations of an RO System?

There is no doubt an RO water purifier is the best way to have purified and filtered drinking. However, there are certain benefits and drawbacks to these. Let us have a look at the advantages and disadvantages below:

Advantages of an RO system

  • An RO system helps in removing 98% of TDS from the water
  • It effectively removes harmful contaminants present in the water.
  • It removes odours and bad tastes from the water
  • An RO water purifying system is easy to install.
  • You can easily maintain an RO system.
  • It delivers purified water having fewer contaminants.
  • An RO purifier removes contaminants, including lead, fluoride, chlorine, dissolved salts from water up to 99 percent.
  • It protects people from falling prey to several diseases like high blood pressure, low fertility, etc.
  • It minimizes the risk of anaemic conditions and other brain-related issues in small children.
  • The reverse osmosis process is an environmental-friendly method. It is the best alternative to bottled water.
  • The RO purified water is ideal for cooking.

Disadvantages of an RO System

Below are some of the disadvantages of the reverse osmosis purifying system:

  • A lot of water gets wasted during the water purification process. This discarded water is not ideal for use.
  • Although an RO purifying system helps in removing the contaminants, it cannot prevent small particles like fluoride from entering your water system.
  • You can notice a pressure drop in the rate of water flow.
  • You need to dispose of the discarded water properly.


1. Can I Connect My RO System To My Refrigerator Or Ice Machine?

Ans: Most RO water purifier systems that are under-sink come plumbed to the incoming cold water supply line, the drain, and an independent faucet. However, it is possible to connect your system to the refrigerator or your ice machine. For that, you need to seek the help of a professional who can get the work done for you.

The plumber will connect the RO system to your fridge by running a quarter-inch tube between your under-sink RO unit and the fridge. However, the key consideration factor for this is the water pressure. If you are not aware of this, you can refer to the user manual. The pressure from your RO unit is about two-thirds of the water pressure coming from the incoming supply line.

2. Does A Reverse Osmosis System Make Noise When Operating?

Ans: It is a known fact that all RO water purifying systems tend to be silent when operating. However, you may hear certain sounds like gurgling. This refers to the sound of the discarded water that flows through the drain pipe from the membrane. This sound is very common, and apart from this, you will not hear any noise. In the reverse osmosis purifying system, the contaminated water gets flushed away from the crossflow water. This continuous flushing helps in keeping the foul from the unit at bay.

Sometimes, you may hear other sounds like a hissing noise. In such a case, seek the help of a professional immediately. This sound can be an indication that there is a problem with the water pressure, or there may be an air gap or a leak in the unit.

If yours is a non-air gap faucet, then your system will not make any gurgling noise. This is because the drain pipe from the RO membrane flows directly into the sink drain line. Hence, it is very quiet when compared to the air-gap faucets.

3. How Do You Compare The RO Water To Bottled Water?

Ans: For most people, a comparison between the RO purified water and bottled water is inevitable. And thus, they even prefer the former over the latter. The reverse osmosis process incorporates carbon filtration that will help in removing harmful contaminants, like lead, fluoride, chlorine, dissolved salts, pesticides, etc., from the water. This filtration makes the water healthy and safe to consume. Furthermore, it improves the taste of the water.

Unlike the bottled or distilled water that has a bland taste, the RO process leaves a small number of minerals and salts in the water. This improves the taste of the water, as well.

Here is the best part. You do not have to buy a bottle way and further, save the expenses on it. Moreover, it is an eco-friendly option as you are not adding water bottles. That said, you will have naturally fresh and safe drinking water available right at your kitchen tap.

4. Are all RO purifying systems and filters the same?

Ans: We all know that there is a multitude of RO water purifying systems available in the market. While most of them look similar in terms of components and design, they actually differ in functionality. There are many different Reverse Osmosis (RO) water filtration systems on the market. Let us see the significant differences between the RO systems.

You can differentiate the reverse osmosis water purifying systems in three basic ways mentioned below:
* The RO systems differ in the number of filters used and also the stages of filtration.
* The quality of components that an RO system contains varies from model to model
* The amount of water an RO purifying system filters per day are different for different units.


I hope this article cleared the air on what an RO water purifier is. This write-up should help you gain a complete understanding of reverse osmosis works. Now that you know its significance, what is the delay? Go, invest in a quality and branded RO purifying system that gives you purified and safe drinking water. Save your family and yourself from getting prone to water-borne diseases.

If you need more information on this topic or have any questions, write to us. If you feel that we missed out on any points, please feel free to let us know. Do not hesitate to add your inputs to this article provide us with your valuable suggestions. We would love to hear from you.

Stay healthy and stay safe!!!

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