The number of filtration stages required by a reverse osmosis system is often a question a lot of people ask. There are different types of systems available and they all vary based on their filtration stages. Although there are other features that make them different, the filtration stage is the major difference between different types of RO systems.
Whenever you are considering an investment in a reverse osmosis water filtration system, it is important to consider the required numbers of filtration stage to make sure you are investing in the right one. So, what is the most ideal number of filtration stages a reverse osmosis should have?
To understand this, let’s first explain the functionalities of a RO system and how it really works.
The most basic RO systems that were first designed have only two stages.
The first stage: uses a carbon block to filter certain contaminants. Of course, this stage does not take care of some micro substances because of the largeness of the pores. But it reduces the extent of germs and contaminants by preventing certain dissolved solids from passing through the carbon filter. This first stage of filtration is known as pre-filtration since it takes place before the RO membrane filtration phase.
The next stage: is the passage of water through the RO membrane. The RO membrane itself has very tiny pores that can filter in a molecular level. This means that it does not allow very tiny particles to pass through and can only allow water to pass through under pressure. The pores at the membrane are so tiny that it allows only water to pass under a very high pressure. The more pressure you have within the membrane the faster flow rate of the water. Tap water does not have a high pressure, which means that the flow rate of water into the system will be considerably slow. To solve this problem, the system usually comes with a pressurized tank which fills up from the best reverse osmosis system. When you need to draw out drinking water, pressure is applied on the small tap through the tank and the water flows at a normal rate of about 5 seconds to fill up the glass. But there is a problem here. If water is stored in the tank for a very long time, it can develop taste, which may not be conducive for drinking. This is where the introduction of more filtration stages comes into play.
The third stage: is known as the post filtration stage where the second carbon filter is kept between the tank and the tap to remove whatever form of taste that may be left after the second filtration. This is the third filtration stage and at this stage, almost all contaminants and debris would have been removed and thrown into the drain.
The fourth stage: is usually an augmentation of the third stage filtration. Here, a sediment filter is placed before the carbon filter to trap some of the dirt and debris before they find their way into the carbon filter. This is done to make the carbon filters last for a long time since they are more expensive to replace. If sediments and other contaminants block them often, they may develop problems soon. But the sediment filter can take care of these sediments before they go on to cause problems for the carbon filter. This is the whole idea behind the fourth filtration stage of reverse osmosis system
The 5th stage: is not necessarily a filtration stage but a process of re-introducing some of the minerals the membranes filtered out during the filtration stages. Minerals such as calcium and magnesium are removed when the water passes through the first few stages of filtration. The fifth stage is intended to re-introduce these minerals into the water, since they are very beneficial to our overall health
The 6th, 7th and 8th stages of filtration: are just an improvement on the previous stages of filtration. These stages claim to remove whatever contaminants that escaped the previous stages of filtration. At the end of these final stages, the water will be carefully filtered and all debris and contaminants that were present in the water would have been trapped. This is the basic idea behind the various stages of water filtration used by the reverse osmosis system.
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