Why do we need to know the pH of the water?

As we all remember from school chemistry course, pH – the unit of activity of hydrogen ions, equal to the reciprocal of the logarithm of activity of hydrogen ions. Thus, water with a pH equal to 7, 10^-7 mol / liter of hydrogen ions, and water with a pH of 6 – 10^-6 mol / liter. The scale of pH values can vary in the range from 0 to 14.

In General, water with a pH less than 7 is considered acidic and a pH greater than 7-alkaline. The normal pH range for surface water systems is in the range from 6.5 to 8.5 and for groundwater systems – from 6 to 8.5.

The pH Value of water (H₂0) is equal to 7 at 25 °C , but contact with carbon dioxide in the atmosphere this equilibrium is shifted to a pH of about 5.2 m. Because of the close Association of pH with atmospheric gases and temperature is strongly recommended, so the water was checked as quickly as possible. Because the pH of water is a measure of the stability of the acidic or alkaline reaction, and does not give a complete picture of the characteristics or the reason for the restrictions on the water supply.

Soft water

In General water with low pH (less than 6.5) is acidic, soft and corrosive. Thus, water can penetrate metal ions such as iron, manganese, copper, lead and zinc from the aquifer, plumbing and piping. Therefore, water with low pH can:

• Contain elevated levels of toxic metals;
• To cause premature failure of metal pipes;
• To have a metallic or sour taste;
• To paint on linen;
• Have the characteristic "blue-green" staining of sinks and drains.

The Main way to solve the problem of low pH water is the use of a Converter. He delivers the solution in the water to prevent the reaction of water with domestic water supply or electrolytic corrosion. A typical catalytic Converter – chemical soda ash. Neutralization of this tool increases the sodium content of the water.

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Hard water

Water with a pH above 8.5 is tough. It is not dangerous for health, but can cause aesthetic problems. These problems include:

• The Formation of "scale" or precipitate on piping and fixtures.
• Alkaline taste in the water that can make coffee taste bitter.
• Limescale on the utensils, washing machine pools.
• The Difficulty in obtaining a foam of soap and detergents and the formation of insoluble deposits on clothes, etc.
• The Reduction of efficiency of electric water heaters.

Usually these problems occur when the stiffness varies in the range from 100 to 200 milligrams of CaCO₃/l, equivalent to 12 grams per gallon. Water can be softened through the use of ion exchange or by addition of ash, lime-soda mixture, but both processes increase the sodium content in the water.

PH drinking water

Careful attention to pH control is necessary at all stages of water treatment to ensure satisfactory quality and disinfection of water. Although water pH usually has no direct impact on consumers, it is one of the most important operational water quality parameters. For effective disinfection with chlorine the pH should preferably be less than 8. The PH of the water entering the distribution system must be controlled to minimize corrosion of pipes. Failure to do so may lead to contamination of drinking water and adverse effects on its taste, odour and appearance.

The Optimum pH value will vary for different materials depending on the composition of the water and nature of construction materials used in the distribution system, but most often it is in the range of 6.5-9.5. Extreme values of pH can result from accidental spills, damage to the treatment facilities.

The Ideal pH level of ionized water for long term human consumption is between 8.5 and 9.5 (and never exceeds 10,0) with the ideal ORP value around 200mV-300mV (and in any case not higher than 400mV).

The PH of the water in the pool

As mentioned above, pH – an important feature not only for drinking water but for swimming pools as for water disinfection is still mainly used chlorination and the use of chlorine disinfection is highly dependent on the initial pH level of the water.

Chlorine is the main disinfecting agent to prevent the development of infections in public swimming pools, but chlorine also reacts with organic substances in water to form disinfection by-products (PPD): organic matter-derived humic substances, resulting from the interaction of water with the sweat, urine, hair, skin cells and residues of personal care products that fall into the water by swimmers. The contents of PPD may be measured as the sum of all halogenated compounds. Some PPAs increase the risk of developing asthma, are carcinogens or irritate the eyes and skin.

Chlorine is the common name of hydrochloric acid, which forms chlorine gas reacting with water. When dissolved in water, the acid forms hypochlorite and has a value of pKa of 7.5.

Hydrochloric acid is much more effective than hypochlorite, killing bacteria, cysts, spores, and inactive virus. Thus,if the pH in a swimming pool is located on the lower level of the control range, a smaller amount of chlorine necessary to obtain the same degree of disinfection, and therefore in the water produce less potentially dangerous PPD. As shown by numerous studies, the optimal level of pH pool water is between 7.5 and 8.0. When pH decreases by only 1-0,5 units (to 7.0 and 6.5) significantly increases the level of PPD, which also still genotoxic.

Methods of determining pH

The pH Scale is a logarithmic scale, which means that each increase or decrease of 1 unit represents a change by a factor of 10. For example, a solution with pH 11 is 10 times more alkaline than a solution with pH 10. There are several methods how to determine the pH of the water.

Determination of pH using test strips

Test strips represent the litmus paper that reacts color change to the pH fluctuations. You can buy them in pet stores because often they are used to determine the pH of the water in the aquarium (even a slight fluctuation of this indicator can lead to fish kills).

When contact with water the color of the test strip will change. You have only to compare the final color with the sample color scale on the package and get a specific value. This method of pH determination is fast, simple, cheap, but has a fairly large error.

Litmus paper "Rettinger"

You can Buy pH strips in medical equipment stores in your city. After analyzing the different ph tests (ranging from cheap to expensive Chinese and Dutch), we came to the conclusion that the minimum error in the reading give the German ph strips "Rettinger". In the package are the indicator scale between 1 and 14 (maximum available interval!) 80 ph strips, which is enough for a long time. Using these strips it is possible to measure not only the ph of the water, but the ph of such bodily fluids as saliva, urine and so on. As a good ph meter is quite expensive (about 3000rub), and they will have to buy buffer solutions for calibration , litmus paper "Rettinger" , the price of which does not exceed 250-350 rubles, will be your indispensable assistant in the accurate determination of ph level.

Determination of pH using pH meter

In a plastic or glass Cup is taken water sample (20-30 ml). The transducer should be rinsed with a small amount of distilled water, and then immersed in the solution together with the temperature sensor. The scale of the instrument shows you the exact pH of the investigated solution. This should take into account that the measurement accuracy is affected by regular calibration of the device for which use standard solutions with known pH value. This method of determining pH is accurate, simple, fast, but require large material costs compared with the previous and basic knowledge of laboratory equipment and chemical solutions.

Thus, the pH of the water – is not just a term from chemistry school course, but also an indicator of water quality that must be controlled in order to avoid hardware issues and health.