As feed water (dark green) enters the first three housings, it will typically get filtered through a sediment filter to prevent clogging, and carbon filters to remove organic contaminants as well as chlorine, bad taste and odor.
Once the pre-filtration has completed, the water passes through the reverse osmosis membrane. High water pressure is typically needed to force the water to pass through the tiny sub-micron pores. Since not all the water can pass through the membrane, it will create waste water which flows down the drain (purple).
As water slowly gets enough pressure to push through the membrane, it will eventually start filling the tank line (yellow). Once the tank fills, it will turn the system off once the pressure equalizes in the hydraulic shut off valve - not seen.
When water is demanded at the faucet, water is drawn from the tank and flow is reversed through the tank line (yellow) and passes through the post filter and up the faucet line (light green).
The system then repeats as needed.
Below are the typical rejection (removal) percentages of a standard
thin film (TFC) reverse osmosis membrane. These are averages based on
experience and are generally accepted within the industry. They are not a
guarantee of performance. Actual rejection can vary according to the
chemistry of the water, temperature, pressure, pH and other factors.
The reverse osmosis process uses a semi-permeable membrane to reject a wide variety of impurities. Here is a partial list. Permeate flow and salt rejection based on the following test conditions: 250 ppm softened tap water, 77°F (25°C), 15% recovery and the specified applied pressure of 50 psi; Minimum salt rejection is 97%;Permeate flows may vary +/-20%.
Reverse osmosis (RO) is a process used to purify water. Basically it removes large molecules (like salt) and minerals from the water. This makes the water purer and safer to drink. The good news is that there are reverse osmosis systems for home. Since the process is easy and the mechanism that does it is not that big or expensive you can improve your tap water, or if you have a source of saline water, you can desalinize it and use it for your plants.
Water resulting from 5 stage reverse osmosis systems is sometimes considered a rival of alkaline water by itself. What is alkaline water you ask? Well alkaline water is water that has had its PH raised above 7.0, basically water with a low oxidation reduction potential. Tap water in most countries has a PH of around 8.5, to reduce its corrosiveness in order to protect the concrete drains and copper pipes it will travel through and sometimes it may have some alkalinity. So if you want to have filtered water, then alkaline water by itself is probably not the answer. Alkaline water reduces the amount of oxidation your body naturally goes through. What this means for you is that you may feel like you can recover faster after workouts, have more energy, and reduce the natural breakdown in your body. Alkaline water may give you positive results but there is no filtration involved. It's definitely best to include reverse osmosis with an alkaline filter. This way you get the best of both worlds. You get excellent filtration through reverse osmosis removing over 90% of contaminants and you put back good positive minerals and alkalinity back in the water. Although there are no actual studies that backs up these claims of alkaline water, there has been an uprising of positive feedback from people who drink alkaline water.
RO water filtration systems are used in wide variety of circumstances including: purifying tap water, humidification, recycling car wash water, rinse waters, biomedical applications and laboratory applications, photography, dialysis, pharmaceutical production, cosmetics, greenhouses and animal feed, the water used for chemical processes, in battery water, and much more. It is used pretty much anywhere purified water is needed. Of course, if you are just a regular Joe you will most likely be interested only in purifying your drinking water, and maybe having some pure water for your plants and pets.
So how do home RO water purifiers actually work? You have a membrane with very tiny holes separates a container of water in two. On one side you have unprocessed water to which pressure is applied in order to push it through the membrane. Because water molecules are small they easily pass through the filter, while bigger molecules and minerals do not. This is reverse osmosis. Why is it reverse? Because osmosis would actually work the other way. The less contaminated water would naturally flow into the contaminated water, because it has the smaller molecules.
Through this simple process of filtering, many contaminants are removed, making the water that results from reverse osmosis akin to distilled water. It would be wrong to say that alkaline water is not in the same league with RO water. Alkaline water is more of a positive balance in the oxidation levels. Alkaline water does a great job at reducing the oxidation your body goes through. RO water is not the end all/cure all diseases, but drinking it is a good way to ensure that you stay healthier and avoid unnecessary risks that often come with drinking unfiltered tap water, especially if you live in a large city. And one more thing: you can stop buying bottled water, it is probably not from springs and in some cases the regulations in place for your tap water are tougher than those for bottled water.