Reverse Osmosis Water or Distilled Water?: That is the question.

reverse-osmosisBy Hannah Henegar

First off, what is osmosis? Osmosis is one of nature’s fascinating phenomenons where a weaker saline solution will migrate to a strong saline solution. An example that is well known to everyone is the way our kidneys absorb water from the blood. This is one of the most important processes in nature.

What is reverse osmosis?

Reverse osmosis is the process of osmosis in reverse. Reverse osmosis is a process where the water is demineralized or deionized by pushing it under pressure through a semi-permeable reverse osmosis membrane. Energy is applied to the more saline solution to be able to ‘push’ the water through the reverse osmosis membrane. This occurs by applying pressure that is greater than the naturally occurring osmotic pressure in order to demineralize or deionize the water in the process. The semi-permeable membrane allows pure water through while keeping the contaminants out. The membrane allows between 95-99% of dissolved salts to be left behind. The demineralized water is called permeate (or product) water due to the salts being removed from it.

The Reverse Osmosis System

The reverse osmosis system utilizes cross filtration rather than standard filtration where the contaminants and salts are collected within the filter media. Cross filtration involves the solution passing through (crossing) the reverse osmosis filter with two outlets: the demineralized water goes one way and the contaminated water goes another. The cross flow filtration allows water to sweep away contaminant build up while allowing enough turbulence to keep the membrane surface clean.

What will reverse osmosis remove from water?

Reverse Osmosis is capable of removing up to 99% of the dissolved salts, particles, colloids, organics, bacteria and pyrogens from the feed water. However, a RO system should not be relied upon to remove 100% of bacteria and viruses. A RO membrane rejects contaminants based on their size and charge.

Reverse Osmosis is very effective in treating brackish water (slightly salty water normally found in estuaries). The RO system is also used to treat surface and ground-water for both large and small flows applications. Some examples of industries that use RO water include pharmaceutical, boiler feed water, food and beverage, metal finishing and semiconductor manufacturing to name a few.

Reverse Osmosis is an effective and proven technology to produce water that is suitable for many industrial applications that require demineralized or deionized water. Further post treatment after the RO system such as mixed bed deionization can increase the quality of the RO permeate and make it suitable for the most demanding applications. With the correct system design, maintenance program, and experienced service support, an RO system can provide many years of high purity water.

Is it safe enough to drink?

Since reverse osmosis water can be highly purified, is it safe to drink this water?     Let’s take a look at the difference between two types of water: distilled and purified. Is distilled water safe to drink? Distilled water is water that is created through the process of distillation. In the process of distillation, the contaminants are boiled out making a pure water product. Many of the contaminants found in water are inorganic minerals, metals etc. As the water (with its contaminants) is boiled, the pure water turns into steam and is captured and cooled and thus becomes distilled water.  As a result of this distillation process, drinking distilled water is safe.

What is purified water?

Purified water is often confused with filtered water. While both types of water are subject to some sort of filtration, purified water is cleansed and purified through additional purification processes, typically reverse osmosis, distillation or deionization. The resultant product, “purified” water, is of significantly higher purity than either spring water, tap water or filtered water. A properly designed and functioning purification system will produce an extremely high water purity every time, regardless of variations in the original water source. This is where reverse osmosis systems come into play with the purification process.

The most interesting part is the fact that distilled water is purified water.  There’s nothing wrong with drinking it. The process of distillation is one of the technologies used to purify water.  Reverse osmosis is another technology that is used to purify water.  The big difference is that boiling water consumes a tremendous amount of energy. Conversely, reverse osmosis technology consumes far less energy and the end result is considerably more cost effective.