In recent years, Reverse Osmosis has become synonymous with water purification. Brands have proliferated in the market with attractive offers on their RO purifiers. So much so that even if your TDS (Total Dissolved Solids) level is well under 500 ppm, you still feel you are missing out on something if you don’t purchase an RO water purifier.
What is Reverse Osmosis?
Osmosis is a naturally occurring phenomenon in which the solvent (especially water) flows from a solution with a lower concentration to a solution with a higher concentration through a semipermeable membrane until the concentrations on either side of the membrane are equalized and an equilibrium is reached. As water passes through the membrane to the solution with higher concentration, the level of liquid in its compartment will rise until enough pressure, caused by the difference in levels between the two compartments, is generated to stop the osmosis. This pressure, equivalent to a force that the osmosis seems to exert in trying to equalize concentrations on both sides of the membrane, is called osmotic pressure.
Now, let’s see what Reverse Osmosis is. If pressure greater than the osmotic pressure is applied to the high concentration solution, the direction of water flow through the membrane can be reversed. This is called reverse osmosis. Note that this reversed flow produces pure water from the solution with the higher concentration since the membrane is not permeable to salt. This is why a steady supply of tap water with sufficient force of water supply is required to achieve Reverse Osmosis purification.
A few applications of Reverse Osmosis are:
- Large scale industrial desalination
- Small scale water purification
- Maple syrup, in fact, is produced using osmosis to separate the sugary concentrate from water in sap.
- The dairy industry uses reverse osmosis filtration to concentrate whey and milk
- The wine industry has begun using it to filter out undesirable elements like some acids, smoke, or to control alcohol content.
- Reverse osmosis is used to create pure ethanol, free from contaminants.
Working technology of Reverse Osmosis Water Purifier
An RO system typically includes five or six stages of purification. An RO purifier is often used in conjunction with UV purifier and Ultrafiltration to achieve a near-distilled-water quality of water output. The most important parts of an RO purifier are the sediment pre-filter, carbon pre-filter, RO semipermeable membrane, carbon post-filter, and the storage tank.
- The sediment pre-filter works like a sieve to separate large particles and a few dissolved solids. It protects the membrane against salt, silt, and chlorine. Thus, the presence of this pre-filter helps increase the life of the RO semipermeable membrane.
- The carbon pre-filter cartridge removes odor, taste, contaminants, and chlorine. It is also helpful for insoluble lead reduction. It further treats the water that enters the RO purifier.
- RO semipermeable membrane is made of very minute pores. They are approximately 0.0005 microns in size (bacteria are 0.2 to 1 micron & viruses are 0.02 to 0.4 microns). It is the most critical part of an RO purifier responsible for eliminating more than 95% of the total dissolved solids in water.
- The Carbon post-filter is also known as a polish filter. This filter eliminates odor and bad taste, with the by-product tasting sweeter and fresher. It is the last step before the water flows out of the faucet of the filter.
- Mineral cartridges like Copper cartridges are plugged into the purifier to infuse fresh mineral ions into the water. This is a contrivance to overcome the demineralization of water that happens because of Reverse Osmosis.
What are the advantages of using an RO water purifier?
- Harmful dissolved contaminants are nearly eliminated by RO. The Total Dissolved Solids are eliminated from the feed water up to a whopping 99%. Reverse Osmosis not only protects you from waterborne diseases but also prevents dental disorders like fluorosis. It also removes sediments, salts, Chlorine, Arsenic, VOC (Volatile Organic Compounds), pesticides, herbicides, etc.
- The Copper infusion from mineralizer cartridges makes the water more tasty and healthy as you can now reap the benefits of consuming copper. It improves digestion, boosts immunity, helps fight obesity, and improves overall well-being.
- Bad odors and tastes are removed during various filtration processes involved in the RO purifier. Some brands like Pureit have come up with a Germ Kill Kit which is a combination of efficient filters like the Pre-Sediment Filter., Pre-RO Carbon Filter, Mesh Filter, Post-RO Membrane, TDS Modulator, MF Membrane, and RO Membrane.
- RO is environmentally friendly compared to drinking bottled water. It also makes the recycling of water less complicated.
So, does the RO water purifier remove all microorganisms?
More than 95% of the Total Dissolved Solids including organic matter and inorganic matter are removed. However, not all bacteria and viruses are removed as they can grow on the parts of the purifier and seep into the water. That is why, it is recommended that RO is used along with UV filtration which deactivates 99.9% of the microbes, and Ultrafiltration which removes the remnants of the UV filtration. Thus, it nearly eliminates the probability of you contracting waterborne diseases.
How does the TDS get modulated?
An RO semipermeable membrane cannot tell the good minerals from the toxic ones. So, you end up losing more than 95% of the total dissolved solids. According to the Bureau of Indian Standards, you don’t even need to purchase an RO unless the TDS levels of your water supply exceed 500 ppm. The ideal TDS level is between 300 and 500 ppm. The RO water typically has a TDS level of around 150 ppm. Water with TDS levels of 150 ppm does not have a good taste because of the elimination of essential minerals like sodium, magnesium, and calcium. Therefore, the water has a lower pH level and hence tastes bitter.
So, there are two ways by which good minerals are added back to your filtered water. One way is through using mineralizer cartridges that infuse fresh mineral ions. Another way is by using a TDS modulator in the RO purifier. In purifiers that use a TDS modulator, water enters the purifier in two batches. The first half is purified by RO membrane, while the second half is purified by UV and UF technologies. These purifiers ensure that both the batches of water are merged before generating the output. Thus, the ratio of TDS in the water is increased and the water tastes better.
Does RO waste water?
Though it is true that RO water purifiers waste a lot of water, technology has kept pace with the anomaly. Brands like Pureit have come up with Eco Recovery technology which saves more water than any other RO. Also, the RO wastewater does not have to be discarded altogether as it can be repurposed for gardening, cleaning your vehicle, etc.
Read on to find out about the best RO water purifier in India and only then, invest in an RO system.