What Are The Stages Of Reverse Osmosis?
It’s a fascinating topic that generates a lot of questions, and as more systems with five or more stages become available, it’s critical to understand what each stage does and whether it’s a good investment.
To truly understanding this, you must first understand what a basic RO system is and how it works.
In its most basic form, reverse osmosis requires only two steps. The initial stage, the carbon block, fulfills two tasks. It filters down to a specific micron rating (a micron is a unit of measurement; when someone talks about filtering down to a specific micron level, they’re referring to how small a particle would have to be to pass through the filter) and removes compounds through a chemical reaction (chemicals in the water bond onto the carbon block and get stuck there). Because it occurs before the RO Plant Price in Pakistan, this is referred to as ‘pre-filtration’ in a RO system.
The second stage, the RO membrane, is a thin composite film that filters the majority of contaminants in the water at a molecular level, rejecting them based on size or electrical charge. Only under pressure can water flow through the perforations or ‘pores’ in the film, and the higher the pressure, the faster the water can flow through. Because the flow rate of pure water via a RO membrane is slow due to low tap water pressure, filling one glass would take several minutes.
Reverse osmosis systems (like the one seen above) frequently contain a tank to combat this. This tank is pressurized, and the RO gradually fills it. When drinking water is required, the small tap is squeezed, and the tank empties at a highly useful flow rate (5-8 seconds to fill a glass).
The extra stages are activated at this point. The filtered water can develop a taste since it is stored in a tank with an internal rubber bladder, especially if the tank is left in for an extended period of time. The third stage is called “post-treatment.” A second Carbon filter is added between the tap and the tank to eliminate any lingering flavor from the water stored in the tank.
The three phases are pre-filtration, reverse osmosis membrane, and post-filtration. Any more than that, and you’re starting to invest in “bells and whistles” that will cost you a lot of money to replace.
Many individuals will add a sediment filter before the initial carbon filter. This sediment filter has the appearance of finely woven cotton wool. The sediment filter will filter particles out of the water before they reach the first carbon filter, which is beneficial. Carbon filters cost more to replace than sediment filters and are more likely to clog. The sediment filter has a higher micron grade than the carbon filter, and it protects the carbon from overheating, much like the carbon protects the RO membrane.
5 Stage: Some people consider the tank to be a stage, while others will start adding an ever-increasing number of add-on filters that do an ever-increasing number of ‘wonderful things to the water, including re-introducing many of the minerals and other contaminants that your filter has just removed.
Anti-scalant pre-filters will be employed, for example, to keep the RO membrane from scaling. As we know from our parent company’s years of experience creating containerized reverse osmosis facilities for major companies, anti-scalant is a typical approach in large industrial reverse osmosis applications. The issue is that investing in such small residential systems is not financially feasible. The cost of utilizing the anti-scalant cartridge is less expensive than replacing the RO membranes. Additionally, those cartridges leak additional chemicals into the water prior to the Reverse Osmosis membrane, all of which are washed down the drain and returned to the environment. As a result, they’re also a bad idea in this aspect.
This line of thinking that a 6 stage will surely be better than a 5 stage, and so on, is actually just a ploy to convince consumers to buy more than they need. Because the RO membrane does all of the heavy liftings, and all systems have one, you can be confident that the water quality given by these subsequent steps will be no better.
Another aspect worth highlighting is that you’ll have to pay for 8 different replacement cartridges when it’s time to maintain your 8-stage Reverse Osmosis system, converting a small investment into a waste of money.
Summary: The best water comes from a carbon filter paired with a reverse osmosis membrane; everything else will cost you a lot more money for little or no benefit. Because the flow rate of RO is not realistic on tap water pressure, a tank is strongly advised if you intend to use your system for drinking water in your home.
We’ve been in business since 1994 and have established a select line of high-quality systems that provide excellent value. Take a look at our four-stage reverse osmosis system, which we use ourselves.