How Does A Reverse Osmosis (RO) System Work

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When you are looking for a water filter that will provide you with an excellent drinking experience, RO filters are one of the most popular choices for both residential and commercial use.

When you take a sip from the water after filtering through a reverse osmosis system, you’ll know the difference in the taste and crisp. Water that is filtered through the RO method is fresher and tastier because it is free from all the harmful chemicals.

Today, millions of households and businesses have chosen RO filters because it provides a great taste of water, fully automated, reasonably priced, and safe.

Choosing a reverse osmosis water filtration system for your family’s needs is the best decision you can make because these systems are intended to purify your water like no other filter.

The first step to healthy drinking water with an RO system is learning how it works.In this article, you are going to know about the reverse osmosis filtration system more than you expected.

What Is Reverse Osmosis?

Reverse osmosis is basically a water filtration process in which contaminants are reduced and water is purified when it is passed with force through a semi-permeable membrane.

Fact! Water flows from the more concentrated side that is the contaminated side to a less concentrated side with fewer contaminants.

The water that is filtered after this process is called permeate and the leftover concentrated water is called brine.

The membrane, through which water flows through, has small pores that allow water molecules to flow between both sides of the membrane. When pressure is applied to the water, only clean water comes out, while the dirt remains behind.

How Does Reverse Osmosis System Works

Reverse osmosis systems are designed to remove sediments and chlorine from your drinking water to make it drinkable. It does so with the help of a pre-filter before the water goes in the semi-permeable membrane for further filtration.

This RO membrane passes the water through another pre-filter that further polishes and purifies the water. Once the filtration process is completed, the water is stored in the RO storage tank where it is held until needed.

The reverse osmosis system has further different stages that are dependant on the pre and post-filters present in your system.

Stages of an RO filter

RO filter systems have 3 to 5 stages of the filter. Each system carries a sediment filter and a carbon filter along with the RO membrane.

The filters are either called post filters or pre-filters. Each system has a one or more of the below-listed filters:

Sediment filter: This filter reduces sand, dust, dirt, and rust.

Carbon filter: It removes all the volatile compounds (VOCs), chlorine, and other harmful contaminants. It also removes bad taste and odor from water.

Semi-permeable filter: This filter membrane removes up to 98% of total dissolved solids (TDs)

Contaminants That A Reverse Osmosis System Removes

RO systems are a huge contaminant remover that uses sediment and carbon filtration to remove harmful compounds like arsenic from the water. Below is a list of all the contaminants that a reverse osmosis system is capable of removing.

  • Fluoride
  • Salt
  • Sediment
  • Chlorine
  • Arsenic
  • VOCs
  • Herbicides and pesticides
  • Bacteria 
  • Viruses 
  • Other microorganisms 

Basic Components Of An RO System

Cold water line valve

This valve fits on to the cold water supply. This is the water source of the RO system.


There are more than one pre-filters used in the RO system. The most commonly used are sediment and carbon filters. These filters protect the membrane from salt and sand silt and remove all the contaminants.

Reverse osmosis membrane

Do You Know! This membrane is the main part of the RO system.

This semi-permeable membrane is crafted to remove all the hazardous contaminants from your drinking water by passing it through force ad pressure. After filtration, the water is stored in the storage tank.


Before going through the faucet from the storage tank, the post-filter tests the water through a carbon filter so that the quality of the water is further improved.

Automatic shut-off valve

This valve is designed to conserve and save water when the storage tank is full. This valve automatically shits of the filtration process and the membrane so that no more water flows through them when not needed.

Flow restrictor

The flow restrictor limits the water flow to a decent rate so that the pressure may not damage the system.

It is present in the RO drain line tubing and produces only the amount of water that is needed for drinking.
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