Reverse Osmosis process even though is a simple process of filtering out contaminants from water, it is somehow seen as being enough complicated to be harmful. Quite a few times you might have heard people saying that the water generated by an RO purifier is more acidic than the normal tap supply. If it is, in fact, true, one can resort to eliminating the whole system from the filtration process. However, to understand in depth what really happens in between those molecules, we’ll have to look for the chemical reactions that take place in the filtration process.
Pure water should be neutral and must have pH 7. Water filtered out from RO has a pH level of 5-6 however it is still safe for consumption.
Here is why RO water has a lower pH and how it is still safe for use.
- When water is sent to the RO purifier through an input, the following process takes place. The RO membrane filters out any ions and molecules that it considers as contaminants which mean it filters out big molecules of HCO3 and CO3. The end resulted in pH filtered out depends on the composition of these two along with CO2 in the input feed.
- For a balanced feed between the three, a very less drop is found in pH of the water and this means Reverse Osmosis is not responsible for significant pH drop in the output.
- For the little amount of pH drop observed, When the RO purifies water, if the input is neutral, that means has equal amounts of H+ and OH– ions, the purified result will be free of other contaminants and will have equal amounts of these ions.
- Once it is purified, when exposed to the atmosphere, it reacts with CO2 to form a somewhat acidic solvent thus explaining the lower pH. Now this lower pH is easily observed as the water sent in had many other dissolved salts neutralizing the pH value and after it comes out, the acids formed after reaction with CO2 increases the pH drastically.
- This does not mean that the RO water is unsafe for consumption. The lower acidic levels cause no harm to the body and hence are healthy for consumption. Moreover, it mixes with saliva in the mouth it is neutralized and when reaches the stomach, turns acidic again due to the acids already present.
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