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Surely, everyone who reads this article remembers the simplest experiments with litmus tests in chemistry lessons in high school. Two, at first glance, identical liquids, poured into different glasses, but at the same time equally transparent and having neither smell nor taste, colored those litmus papers in colors opposite to each other by spectrum. The blue-green shade symbolized an alkaline environment, a bright acid-yellow or even orange – acidic.

In this article we will understand: what is the acid-base balance of the liquid (pH), how it affects the human body and, most importantly, we will find out whether water purification by reverse osmosis affects the acidity of water.

What is the acid-base balance of water (pH)?

To be brief – acid-base balance (pH) or acid-base equilibrium is the relative constancy of the ratio of acids and alkalis in a liquid. It is expressed by the molar concentration of ions in solution. This indicator is quite important when analyzing whether the liquid is potentially harmful to a living organism or whether its use will pass without a trace.

The fact is that the acid-base balance (pH) of a living organism is within fairly strict limits - this is the pH level of arterial blood – 7.26 – 7.45. It is generally believed that the closer the pH of the consumed liquid is to the acidic environment (values below 6.0), the greater the harm caused to health by its consumption. Alkaline water (with a pH from 8.0 to 10.0), on the contrary, has a beneficial effect on the human body. The acid-base balance in the region of 7.0 is considered neutral.

In general, doctors and scientists note that the acid-base fluid balance (pH), ranging from 6.0 to 8.0, is relatively neutral and is not a factor that brings any tangible changes to the body's work.

So, in the range of common sience, tap water should have a pH of 7.0, spring water it reaches 8.0, distilled water – 6.0. Cola or other highly carbonated water will have an acidic environment with a pH in the region of 3.0.

How does the reverse osmosis membrane affect the acid-base balance of water (pH)?

There is an opinion among consumers that the reverse osmosis membrane makes water "dead" and greatly reduces the acid-base balance of water (pH). The best way to find out if this is really the case is a visual test of water with a pH meter at the inlet and outlet of the reverse osmosis system.
So we have:

MILWAUKEE PH meter pH 600
AQUABRIGHT ABF-OSMO 6 reverse osmosis system with mineralizer.
Municipal tap water, the original source is an artesian well.


A device for measuring the acid-base balance of liquids.

The essence of the experiment is as follows – we need to make 3 measurements of the acid-base balance level – tap water, water immediately after the reverse osmosis membrane (before it enters the tank), water after the tank and the AQUABRIGHT UGA-LINE linear postfilter (similar to the result of cleaning with the AQUABRIGHT ABF-OSMO 5 reverse osmosis system, without a mineralizer) and water that has passed all 6 stages of the reverse osmosis water purification system – AQUABRIGHT ABF-OSMO 6.

What we have:
The water from the water main has a pH level of 7.1

The water at the outlet of the membrane unit has a pH of 5.9

Water after 5 stages of purification has a pH of 6.7

The water after the mineralizer has a pH of 7.3

In a fact, we see that straight after the reverse osmosis membrane, the water has a more acidic environment, however, at the outlet of the tap of the AQUABRIGHT ABF-OSMO reverse osmosis system, we have water with a neutral level of acid-base balance (pH).

Why does the acid-base balance (pH) decrease in reverse osmotic water?

here are two main reasons why the water at the outlet of the membrane unit of the reverse osmosis system has an acid-base balance (pH) lower than the source water:
1) Low buffering of the liquid.

2) The difference in the size of the ions [H+] and [OH-]

Buffering of the solution is the ability of the solution to keep the pH unchanged when the concentrations of dissolved substances change or additional components are added to it (solution). In general, the more salts dissolved in water, the higher the buffering of the solution. In the case of reverse osmotic water, we get water with a very low content of solutes and, as a result, with low buffering.

As for the size of the ions – let's remember the formula of water – H2O. The Water molecule can be represented as a compound of the OH- hydroxyl group and the H+ cation. The size of the [H+] ion is smaller than [OH−], which allows it to pass through the membrane and shift the acid-base equilibrium. At the exit from the reverse osmotic membrane, the concentration of hydrogen ions in the water becomes greater, while the pH of the water decreases and the acid-base balance shifts towards the acidic medium.

How to normalize the acid-base balance (pH) of water after reverse osmosis membrane?

Firstly, a linear postfilter will help us to partially normalize the acid-base balance of reverse osmotic water. In the reverse osmosis water purification systems AQUABRIGHT ABF-OSMO-5 and ABF-OSMO-6, linear carbon cartridges with activated coconut carbon AQUABRIGHT UGA-LINE are installed. These cartridges are used to carry out additional sorption purification of water accumulated in a 12-liter tank of the AQUABRIGHT ABF-OSMO reverse osmosis system. They also help to increase the level of acid-base balance of water, as they contain activated coconut carbom, which adsorbs carbon dioxide particles dissolved in water, and thereby increases the pH level.

The AQUABRIGHT ABF-OSMO-6 reverse osmosis system has a linear cartridge – mineralizer AQUABRIGHT MINERAL-LINE, which saturates the water with useful minerals and, as a result, increases the buffering of the liquid and changes its environment. Calcium carbonate (natural material - calcite) and magnesium contained in most high-quality mineralizers for reverse osmotic systems, such as AQUABRIGHT MINERAL-LINE, normalize the level of acid-base balance by shifting it towards the main medium.


The calcite mineral in its natural form.

To make a summary - the acid-base balance of drinking water (pH) purified by the reverse osmotic system AQUABRIGHT ABF-OSMO-5 or AQUABRIGHT ABF-OSMO-6 will be at a relatively neutral level, however, if you want to drink more "HEALTHY" water, AQUABRIGHT recommends that you purchase a reverse osmotic system with a mineralizer, such as AQUABRIGHT ABF-OSMO-6, or complete your reverse osmosis system with a linear mineralizer AQUABRIGHT MINERAL-LINE!


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