Grade 6 → Water and its properties ↓
Water purification methods (boiling, filtration, chlorination)
Water is a vital resource that is essential for the survival of all living beings. It is a simple molecule composed of two hydrogen atoms bonded to an oxygen atom, represented by the chemical formula H 2 O
Water covers approximately 71% of the Earth's surface and exists in three states: solid (ice), liquid (water), and gas (steam or vapor).
In addition to its versatility in physical states, water has unique properties, such as its high heat capacity, surface tension, and solvation capabilities. These properties make it essential for a variety of biological and chemical processes. However, despite its abundance, clean and safe water is not always accessible. This necessitates the need to purify water for consumption and daily use.
Boiling is one of the simplest and most effective methods of water purification. It involves heating water to its boiling point to kill harmful microorganisms such as bacteria, viruses and parasites. This process is effective because most germs cannot survive at high temperatures.
Steps to boil water:
- Pour the water into a clean vessel.
- Place the pot over a heat source such as a stove or fire.
- Heat the water until it begins to bubble vigorously, indicating that it has reached the boiling point, which is 100°C or 212°F at sea level.
- To make sure all germs are killed, let the water boil for at least one minute (or three minutes if you're at a higher altitude).
- Switch off the flame and allow the water to cool before drinking it.
While boiling effectively removes microorganisms, it does not remove contaminants such as heavy metals or non-volatile chemicals. Therefore, if the water source is highly contaminated, other purification methods may be necessary.
Filtration is a physical process in which impurities and particles are removed from water using a filter medium. The filter medium can be anything from sand, charcoal or even special commercial filters. Filtration is effective at removing large contaminants such as dirt, sand and some pathogens, but it does not necessarily remove dissolved substances.
Types of filtration:
- Sand filtration: In this, water is passed through a layer of sand, which traps larger particles and impurities.
- Activated charcoal filtration: Activated charcoal filters absorb chemical impurities and some bacteria by providing large surface area for absorption.
- Ceramic filtration: Water passes through a highly porous ceramic material, which filters out sediment, bacteria, and parasites.
How to do simple filtration at home:
- Take a clean container and place a paper towel or piece of cloth over it.
- Lay a layer of sand or activated charcoal on the cloth.
- Carefully pour the water through the filter medium and collect the filtered water in a container.
Filtration is an efficient method for removing visible contaminants and improving the taste and odor of water. However, like boiling, it may need to be supplemented with other methods to ensure complete purification.
Chlorination is a chemical method of purifying water in which chlorine is added to kill bacteria and other pathogens. Chlorine is an effective disinfectant because it attacks the cell walls of microorganisms, rendering them harmless.
Steps of chlorination:
- Calculate the amount of chlorine needed based on the volume of water. Generally, 8 drops of liquid chlorine bleach can purify one gallon of water.
- Add the chlorine to the water and stir well to ensure even distribution.
- Let the water sit for at least 30 minutes. During this time, the chlorine works to inactivate germs.
- Check if the water has a slight chlorine smell, which indicates it is safe to drink.
Chlorination is widely used in municipal water systems and is effective in removing bacteria, viruses, and some protozoa. However, it does not remove all chemical contaminants or sediments.
Purifying water is important for our health and safety. Each method – boiling, filtration and chlorination – has its own merits and limitations. Boiling is reliable for killing microorganisms, filtration can remove particles and improve the taste of water, and chlorination is effective for large-scale disinfection.
In many cases, combining these methods can produce better results. For example, boiling or chlorination followed by filtration ensures clean water that is safe to drink. It is important to be able to use and know how to use these purification techniques, especially in areas where access to clean water is limited or inadequate.
- Boiling point: The temperature at which a liquid changes into a vapor.
- Pollutants: Unwanted impurities or substances that pollute water.
- Pathogens: Harmful microorganisms that can cause disease.
- Solvent: A substance that dissolves a solute to form a solution. Water is known as the universal solvent.
- Always use clean utensils and equipment for water purification.
- Make sure the source of water is suitable for purification and consumption.
- Use caution when handling chlorine and follow recommended guidelines to avoid ingestion or irritation.