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Types of Reverse Osmosis Systems

2 Common Types of Reverse Osmosis Systems You Should Know!

Ever since the advent of reverse osmosis systems for water purification and desalination, many people are adopting them for domestic water filtration. Companies started manufacturing systems that gradually developed to a point where you can now get up to 99% TDS-free water.

That’s almost pure water, something that could only be achieved from rain. But how does that happen?

Well, there are two types of reverse osmosis membranes for different systems that work concurrently with other filtration aspects, such as carbon pre-treatment, to achieve such purity levels.

If you are looking to buy a reverse osmosis system for your kitchen, two main types stand out;

  • Countertop RO systems
  • Under-the-counter RO systems

I fathom how challenging it can get choosing a system that suits your needs. Therefore, this article takes you through the types of reverse osmosis systems to help you cherry-pick from the so many products available.

Read along.

Types of Reverse Osmosis Membranes

Before digging into so many details, let’s first discern the two main types of reverse osmosis membranes for household use.

  • Thin Film Composite Membrane (TFC or TFM)
  • Cellulose Triacetate Membrane (CTA)

Thin Film Composite Membrane

So, what are Thin Film Composite Membranes?

Also abbreviated as TFC or TFM, these are semipermeable membranes used in water purification and desalination systems. Besides being highly permeable and durable, they are also heavily tolerant to extreme pH levels.

However, they are prone to attacks from oxidants and chlorine, making them unsuitable for use in chlorine-treated water.

But that downside doesn’t cloud the fact that the TFC membrane can reject up to 98% of typical impurities. Also, they are not easily subjected to fouling as opposed to the Cellulose Triacetate membranes.

Some consider TFC membrane a molecular sieve with three layer configurations that reject more minerals, filter more water and withstand high pressure.

When fitted in filters, these membranes can work best with under-the-sink reverse osmosis systems giving you a constant supply of filtered water.

Cellulose Triacetate Membrane (CTA)

Cellulose triacetate membrane is a high-performance permeable membrane used for water purification and desalination in RO systems. A standardized membrane structure allows for the production of a wide range of permeability, allowing low flux and high flux performance.

CTA membrane consists of thousands of tiny fibers around a perforated tube, allowing water to go through the outside and permeating the inside of the tube (permeability is outside in). 

Also, it boasts 93% rejection of typical contaminants, a slight drop compared to the 98% of TFC membranes.

One of the most significant upsides of CTM membranes is that it is highly tolerant to chlorine and best suited for water with high chlorine levels. But despite this notable feature, one downside stands out; CTA membranes are highly vulnerable to fouling from Bacteria and other organic contaminants. 

However, treating the water with UV radiation helps deal with the bacteria problem. Even better, the membranes are now designed with chlorine-resistant material so they can last longer.

See also: Installing reverse osmosis system for Aquarium

Types of Reverse Osmosis Systems

You want a constant flow of purified water in your house. For this, it is essential to install an RO system in your kitchen.

But which type should I go for?

Well, you will come across two main types of RO systems;

  • The countertop Reverse Osmosis Systems
  • Under the counter Reverse Osmosis system

Let’s look at each;

1. The countertop Reverse Osmosis System

As the name suggests, countertop RO systems are designed to sit on the counter or above ground. Usually, they come as standalone apparatus that easily connect to any faucet in your water supply.

If you are renting an apartment, this system will best suit your needs as it doesn’t require drilling or additional installation features.

Check out some of its benefits;

  • It is temporary, so you can move with it whenever you are relocating.
  • The system doesn’t require technical expertise during installation.

Despite the benefits, countertop RO systems will require you to have extra space on your counter, which inconveniences those with limited space.

See also: Reverse osmosis system vs Brita

2. Under counter Reverse Osmosis Systems

An under-counter RO system is designed for installation under the sink for easy connection to faucets and to save space. Most households have them installed because of these apparent features.

Under Sink Reverse Osmosis System 2
2 Common Types of Reverse Osmosis Systems You Should Know! 7

Here are some of their benefits;

  • Under the counter, RO systems are easy to use since all you have to do is turn on the faucet and collect purified water.
  • The filtration is continuous as long as the faucet is turned on, giving you a lot of water.

However, it is not all smooth under counter RO systems as more water goes to waste than collected. Additionally, the installation process is pretty complex, considering you have to drill through the walls.

See also: Which is the best reverse osmosis water filter for well water?

FAQs on Types of Reverse Osmosis Systems

Is it bad to Drink RO Water?

During reverse Osmosis, minerals and other contaminants are removed from the water. Some minerals such as magnesium and calcium, which are necessary for our daily diets, are also eliminated. Although drinking RO water isn’t bad, you won’t be benefiting from such valuable minerals.

What should you look for when buying an RO system?

There are certain factors you should look for when buying an RO system.

What most people ignore is the type of membrane used in the filters. If your water is heavily chlorinated, you might want to use an RO system designed with CTA membranes.

If your water doesn’t have chlorine, then a TFC membrane will work just fine. Additionally, you should check on the flow rate, filtration quality, and, most importantly, your budget.

Are all reverse osmosis systems the same?

Basically, the functionality concept for most RO systems is the same. However, what sets them apart is the quality of filters used and the different stages of filtration. More so, they are designed with different types of membranes intended for various water quality levels.

Every home deserves a reverse osmosis system to eliminate toxic minerals and heavy metals such as lead which can cause serious health complications like cancer. Understanding the types of Reverse Osmosis systems is the first step to ensuring you have clean and purified water for household consumption.

From this article, there are two central RO systems that you can have installed in your kitchen; the countertop and the under-counter RO systems. However, you should also consider the type of membrane used so as to pick one that better suits your needs.


Centers of Disease Control and Prevention (CDC): A Guide to Drinking Water Treatment Technologies for Household Use

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