Reverse Osmosis is the favoured water purification method, among others, of the US army around the world, and is one of the best ways to decontaminate water. But what is actually involved in reverse osmosis and why do we need it?
What is Osmosis?
Osmosis is the process by which a high concentration of a substance in solution disperses through a semi-permeable membrane into a less concentrated solution.
In simple terms, if I were to place salt water in a container that would allow salt to pass through it (a semi-permeable barrier) and left the container in pure water, over time the levels of salt would rise in the surrounding water and the salt concentration would drop in my initial solution.
The salt would have diffused into the pure water via osmosis.
Reverse Osmosis, as the name suggests, is merely the opposite of this process.
A series of membranes that will allow only water molecules to pass through, will strain the water for absorbed contaminants.
Of course, while the process of osmosis happens naturally and does not require energy, reverse osmosis requires pressure to force the water through the membranes.
The Reverse Osmosis System
Reverse Osmosis typically happens in five stages:
- Sediment Removal
Water is passed through a sediment cartridge, in order to eliminate suspended particles. Filter cartridges are rated in microns, corresponding to the size of particle they will allow to pass through.
- Carbon Filtration
A carbon filter removes harmful chemicals, particularly chlorine and lime.
- Carbon Block Filter
More chemicals and impurities are removed.
- Reverse Osmosis Membrane
Water passes through a fine membrane and all heavy metals are removed.
- Post Filtration
Water is given a final treatment, which removes all remaining contaminants, along with improving taste and eliminating odour.
Reverse Osmosis offers significant advantages over other water purification processes, since it not only matches the performance of methods like carbon filtering, but excludes significantly more contaminants.
With a simple carbon filter, you will have less protection against bacteria and heavy metals and you may have no protection at all against a host of hazards like viruses, arsenic, sulphates, fluorides or nitrates.
That’s before we get into the superior performance of a reverse osmosis system when it comes to water taste and odour.