How Does a Reverse Osmosis Filter Work : Let’s Know About RO System

How Does a Reverse Osmosis Filter Work

When I was young, I used to be very confused about why people didn’t think of using seawater to drink. Especially one time when there was news about a current drought.

I was kind of frustrated by the fact that humans are not smart enough to realize something that even a 7 years old kid like me can figure out.

My dad has a good time teasing me for having such theories in my little head. And I can’t do anything except laughing at my own naiveness.

Well, you probably are thinking what’s my point of suddenly sharing a story like that. Well, we are here to talk on how does a reverse osmosis filter work today. And for obvious reasons, I got myself drowned by my memories while thinking about this topic.

Keeping my stories aside, let’s know more about reverse osmosis filters.

How Does A Reverse Osmosis System Work & What Is It Actually?

When we talk about reverse osmosis technology, it’s always about turning saltwater into freshwater. Seawater is salty, it can’t be used or drunk directly.

Also, you can’t normally filter seawater since it has hard-to-separate contaminants. However, it’s not impossible and needs a very high level of energy to do so. And that’s why in reverse osmosis filters we can think about purifying something high concentrated such as seawater.

That’s one of the prime reasons why we are using 4000-cubic-miles of freshwater per year to keep human thirst under control but still suffering from a shortage.

Let’s figure out what exactly reverse osmosis is and how the filter with such technology can do this hard-to-guess process for everyday livings.

General Idea on Reverse Osmosis System

Let’s talk about how does a reverse osmosis system work. This system is meant to get rid of any contaminant from unfiltered water. Also, it includes feed water. Through a semipermeable membrane, the water gets forced using pressure and that’s how removal happens.

There are two sides here. The high concentrated side holds more contaminants. On the other hand, there’s quite less contaminates in low concentrated side. And this is where you get clean drinking water. Permeate is a term that refers to freshwater produced here. And the concentrated water that stays behind is known as brine or waste.

The main concept of osmosis is to make water more concentrated while it travels through the membrane. So that equilibrium on both sides is possible. And reverse osmosis is the complete opposite. This means the contaminants get blocked from entering the less concentrated side of membrane.

This formula helps in eliminating dissolved solids such as fluoride and arsenic. There are also carbon filters that help to eliminate bad taste, odors, and chlorine. The sediment filter is also noticeable in RO system that helps to get rid of debris and dirt.

With reverse osmosis, it’s possible to get rid of VOCs, arsenic, sediment, chlorine, fluoride, herbicides, pesticides and of course, salt. Also, it can remove some other contaminants, I just named some popular ones.

The elements that RO can’t deal with are bacteria and viruses. There are sometimes chances of bacteria growing on the membrane and so, you should think about UV disinfection for that.

how does a reverse osmosis system work

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The Filtering Process of Reverse Osmosis System

Now to have a better idea about how does reverse osmosis work to filter water, here is a step by step analysis.

First Step – Before Filtration Phase

The first part of this process takes responsibility to protect membrane. So, it simply gets rids of any large sediment. And this includes dissolved solids as well as chlorine. The sediment or carbon block filter is the cartridge that takes this job. And by that, there’s no chance of blocking in the membrane due to municipal water.

Too hard water is not a proper choice to apply reverse osmosis. It’s always best to use the process for turning good water to great. And so, use hard water that is below 10 grains per gallon. Water softeners installed previous to the RO system can be a good solution.

Second Step – The Magic of Membrane Starts

Now comes the prime stage of reverse osmosis. It starts by forcing the water through a membrane that is semi-permeable. The water molecules have their way through this membrane that is basically synthetic plastic material. The elements that can’t pass this membrane are glucose, urea, and similar large molecules. And that same goes for chlorine, sodium, and calcium as well.

Some RO system also includes TFC or thin-film composite membranes. So that bacterial resistance and the high rejection rate are available. However, these are not too good with chlorine.

Third Step – The Final Filtration for Drinkable Water

There is also another carbon filter that helps in eliminating left-by-mistake contaminates in the water. After this final filtration, water fills the tank for storage and waits for you to use or drink it.

An in-line activated carbon filter also stays that help to get the last polish while coming out of faucet. This helps in removing any flavor or door from water due to system hose or tank. This last polish step is an additional one that makes water incredibly fresh and safe to drink.

How Does A Reverse Osmosis System Work


TDS could be the reason for hard water’s negative taste and so you need to get those dissolved solids out. Sodium replaces harmful minerals. And also, some contaminates tend to stay into the water even after softening. So, reverse osmosis is a very useful system that will make your regular drinking water safer. It’s one ideal solution for every home.

Once you decide to trust this technology, better-tasting coffee and tea will be a regular thing. Also, clearer ice cubes and pure water are going to embrace your health in the best way. It’s one smart investment to make for those who still use bottled water. Since in the long run, you are saving money and doing good for environment as well

Hopefully, now you have a better idea of how does a reverse osmosis filter work. Go for the kitchen sink, basement or whole home up-gradation with this system. Good Luck!