Inverted Osmosis System, Reverse Osmosis, or Reversed Osmosis: Which Term Is Correct?

Understanding reverse osmosis terminology

Inverted Osmosis System, Reverse Osmosis, or Reversed Osmosis: Which Term Is Correct?

Are you looking for an inverted osmosis system to filter your tap water? You may also have come across the terms “reversed osmosis,” “reverse osmosis system,” or “reverse osmosis device.”

These different terms generally refer to the same filtration system, but they are not all accurate.

The answer in a few seconds

The correct technical term is reverse osmosis. The device that uses this process is called an RO system or, in full, a reverse osmosis system.

Terminology

What is the correct spelling?

Correct terms

Reverse osmosis: the filtration process
RO system: the device that uses this process
Reverse osmosis system: the full term
Reverse osmosis filtration system: another correct term

Common but imprecise terms

“Inverted osmosis system”
“Reversed osmosis”
“Reversed osmosis system”

An RO system is not itself “inverted.” It is the natural process of osmosis that is reversed by applying pressure to the water.

The rule to remember

Should you write “reverse osmosis” or “reversed osmosis”?

The correct term is reverse osmosis. This is the term used in the technical terminology for this filtration method.

Use

Reverse osmosis
A reverse osmosis filtration system
A reverse osmosis system

Avoid

Reversed osmosis
An inverted osmosis system
A reversed osmosis system

Although these variations are common in online searches, they generally refer to the same equipment: an RO system.

Meaning

What is an “inverted osmosis system”?

When someone searches for an inverted osmosis system, they are actually looking for a reverse osmosis system.

This device filters water through a very fine membrane. Under pressure, some of the water passes through the membrane, while a large proportion of dissolved substances and unwanted elements are retained and then flushed away.

Depending on the model you choose, the device can be installed under a sink, placed on a countertop, or operate with direct flow.

Filtration principle

How does reverse osmosis work?

Osmosis is a natural process in which water passes through a membrane between two solutions with different concentrations.

Reverse osmosis involves applying enough pressure to the water to force it to flow in the opposite direction to the natural process. The membrane primarily allows water molecules to pass through while retaining a large proportion of dissolved salts and other substances present.

RO water

This is the water that passes through the membrane and can then be dispensed through the faucet.

Concentrate

This stream contains the elements retained by the membrane and is discharged into the wastewater system.

This is why a true membrane-based RO system necessarily produces some wastewater. However, water recovery varies considerably depending on the device’s technology, the water supply pressure, and the quality of the water being treated.

Summary

Which term should you use?

The process is called reverse osmosis.
The device is called an RO system.
The full term is a reverse osmosis system.
“Inverted osmosis system” and “reversed osmosis” are common but technically imprecise terms.

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