pH level in water?
Before learning how to measure water pH, you need to understand what pH is. pH is a scale that measures the level of alkalinity and acidity in water. This scale ranges from 0 to 14, with a neutral level of 7. When the pH is below 7, the water is acidic, and when the pH is above 7, the water is alkaline. pH = 0 represents extremely acidic, while pH = 14 represents extremely alkaline.
When considering the pH of water, each increase in value corresponds to a tenfold increase in alkalinity or acidity. For example, pure water has pH = 7, milk has pH = 6, and coffee has pH = 5. This means that coffee is 10 times more acidic than milk and 100 times more acidic than pure water.
Water always contains dissolved salts and acids, and the amount varies depending on the type of water. Therefore, the pH of water can be higher or lower than neutral. Salt dissolved in water also contributes to the water's characteristic flavor.
What does the pH scale mean?
If the pH is <7, the water is acidic. The lower the index, the stronger the acidity, for example battery acid is extremely concentrated with pH = 0.
If the pH is >8, the water is alkaline. Pure and concentrated alkaline solutions will have a pH = 14.
pH = 7 represents balance, water at this level is neutral and is considered pure water because it is neither acidic nor alkaline.
What is the safe pH level in drinking water?
The ideal water source to support comprehensive and optimal development of the body has a pH level of 6.5 to 8.5. This information has been verified and recommended by the World Health Organization.
How do you understand the safe pH level in water?
The pH of water is not a fixed number but changes according to the environment, weather and human impacts. When measuring pH, if the water has a pH that is too high or too low, it may be a sign of contamination by chemicals such as pesticides, herbicides, or heavy metals.
Highly alkaline water often has an unpleasant taste and odor, while highly acidic water is unsafe to drink and can be harmful to health. Alkaline water can damage and clog pipes, and acidic water can corrode metal equipment.
Water suppliers regularly monitor pH levels to ensure drinking water is safe and sanitary, and can quickly resolve problems if they occur.
The pH of some types of water today
What is the pH of tap water?
Tap water is the type of water we use every day, taken from many different sources such as groundwater, surface water (pond water), or rainwater. All have been chemically treated to destroy pathogens before being provided to people. Because the water source is different, the ingredients in the water are also different. The pH of tap water is usually at 7.5.
Bottled water
Bottled drinking water usually has a pH between 6.5 and 7.5. These types of water must meet strict health standards before being distributed on the market.
RO water
RO water (Reverse Osmosis) is water that has gone through the reverse osmosis process, using a pump to push water through a semi-permeable membrane, removing impurities. The resulting water is highly pure, while impurities are retained. The average pH of RO water ranges from 5.0 to 7.0, suitable and safe for users' health.
There are ways to measure pH in water
How to measure the pH of water
There are 4 common methods to measure water pH:
1. Use litmus paper
Litmus paper is a type of paper made from lichen, most popular when it comes to measuring pH. This method is very simple:
- Put the water sample into a test tube or small cup.
- Dip litmus paper in water.
- Red litmus paper will turn blue if the water is alkaline (pH > 7), and blue litmus paper will turn red if the water is acidic (pH < 7). Neutral water (pH = 7) will not cause litmus paper to change color.
However, litmus paper only indicates whether the water is acidic or alkaline, and cannot accurately measure the pH index.
2. pH test strips
pH test strips are also a popular method and give more accurate results than litmus paper, changing color according to the pH level within 0.5 units:
- Put the water sample into a cup or test tube, dip the test strip into it.
- After about 2 minutes, the test strip will change color.
- Compare the color on the test strip with the color chart to determine the pH index.
3. The solution changes color
This method is often used in the laboratory, using common color-changing solutions:
- Methyl Red: pH < 4, the solution will be red; From pH 4 to 7, the solution will change from red-orange, orange, to yellow; pH > 7 the solution will be yellow.
- Bromothymol Blue: pH below 6, the solution turns yellow; From pH 6 to 8, it changes from yellow-green, green, to blue; pH above 8 the solution will turn blue.
- Phenolphthalein: Colorless when pH is less than 8, red when pH is greater than 10.
Use a pH meter to measure
To ensure accurate testing of water pH, owning a pH meter is an effective solution. To start, you need to calibrate the meter using distilled water. If the measurement is 7.0, the meter has been calibrated and will give accurate results.
The measurement process is very simple: you just need to dip the device's probe into the water sample you want to test. The electronic screen will display results with accuracy to two decimal places, helping you know the exact pH of the water.
Why does pH need to be measured?
Choosing water with the right pH is necessary to not upset the body's balance. With a fairly high water intake, from about 2 liters per day, water with an incorrect pH level will have a direct impact on health. For example, water with a pH that is too low or too high can cause problems such as:
- Water with neutral pH (6.8 - 7.2): Good for health, suitable for daily use.
- Water with high pH (over 8.0): Usually tap water that has been treated with chlorine to kill bacteria, may contain rust from pipes.
- Water with low pH: Usually groundwater contaminated with chemicals such as fertilizers and pesticides.
Refer to pH meter products at:
EMIN water pH meter
Above is information about pH and how to measure it correctly. The pH of common types of water as well as how to measure pH have been fully provided in this article. Choose water with the right pH to ensure the health of you and your family.
