Concept : Purification of Water
Water that we get in our homes usually comes from rivers. However, this
water is contaminated with impurities like sand, silt, clay, soluble
impurities and harmful germs.
So, water needs to be cleaned before it reaches our homes. There are different processes to purify water.
What is the purification of water?
Removing of impurities from the water to make it clean and suitable for drinking is called the purification of water.
Impurities found in water:
Some common impurities found in water are—
- Harmful chemicals
- Disease-causing germs
- Fine sediment particles
- Human/animal faeces
Characteristics of impure water:
- The water appears muddy and greyish.
- It may give off a foul odour.
- It may have an awful taste.
How does water get impure?
- Dumping any sort of garbage can cause the water to get dirty.
- Human activities like washing clothes and utensils, bathing animals etc., can cause a waterbody to become unclean.
- Industrial wastewater, agricultural run-offs, and chemicals can cause the growth of harmful germs in the water, making it unfit for use or consumption.
How is water purified:
Purification of water can be done by different methods. Some of these methods are done at home, while others are used in water treatments plants where water gets purified before being distributed. The common methods of water purification are—
- Boiling of water
- Addition of chemicals
- Using electric water filters
- Sedimentation and decantation
- By using sunlight
Boiling of water:
When water is heated and brought to a rolling boil for about 20 minutes, the heat kills almost all the harmful germs from the water, making it suitable for drinking.
Addition of chemicals:
Chemicals such as chlorine tablets, potassium permanganate or alum can be added to water to kill harmful germs.
Using electric water filters:
Electric water filters, with their complex components, help us get clean and pure water.
Sedimentation and decantation:
In the process of sedimentation, impure water is allowed to stand undisturbed in a container. As a result, impurities like mud or sand settle at the bottom as sediments. Clean water is then transferred into a clean container by the process of decantation.
In this method, impurities that do not dissolve in water are removed by passing the impure water through a filter paper or a muslin cloth.
In this process, impure water is first heated till it gets converted into steam. The impurities are left behind in the container. The steam obtained is then passed through a condenser, where it gets cooled and then changes back into liquid water.
By using sunlight:
Sunlight is used to disinfect water. The steps involved are as follows—
- A transparent bottle is washed properly.
- The bottle is filled with water, and its lid is tightly closed.
- The bottle is then kept horizontally in strong sunlight for at least 6 hours.
- The bottle needs to be left for 2 days if it is cloudy.
- The UV rays coming from the Sun help in killing the germs present in the water.
- The water becomes ready for drinking.
Soluble: Able to mix with water.
Run-off: Draining away of water from land.
Rolling boil: When water vigorously boils and bubbles start appearing continuously which cannot be stopped by stirring the water.
Bottled water is a safe option.
We cannot consider bottled water to be a safe option. The reason is that the bottles are made of plastic that contains chemicals. These chemicals leech into the water gradually, making it not so suitable for drinking.