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Revision Notes

Class 7

Science

Chapter 16 Water A Precious Resource

Water: a Precious Resource Class 7 Science Chapter 16 CBSE Notes - 2025-26

Q: 1. Why is water considered a precious resource for Class 7 students to understand?

Water is considered a precious resource because although the Earth is covered by about 71% water, only a very small fraction (about 0.006%) is available and fit for human use. All living organisms, including plants and animals, depend on this tiny amount of freshwater for survival, making its conservation crucial.

Q: 2. For a quick revision, what is the difference between groundwater and the water table?

For a quick summary, groundwater is the water that is found beneath the Earth's surface in the cracks and spaces in soil, sand, and rock. The water table is the upper level or surface of this zone of saturation. When you dig a well, the level at which you first find water is the water table.

Q: 6. What is the core concept behind drip irrigation as a water management technique?

The core concept of drip irrigation is to conserve water by delivering it directly to the base of the plants, drop by drop. This method is highly efficient as it minimises water loss through evaporation and runoff, ensuring that almost all the water is used by the plants. It is a vital technique for water management in regions with water scarcity.

Science Notes for Chapter 16 Water: a Precious Resource Class 7 - FREE PDF Download

In Cbse Class 7 Science Notes Chapter 16, you will learn all about why water is so precious and how we must use it wisely. This chapter makes you aware of how much water we really have and why saving every drop matters for our future and the planet.

Sometimes, it’s hard to remember all the terms and points in science lessons. With these easy revision notes from Vedantu, understanding important concepts and preparing for exams becomes a lot simpler. You can always check the Class 7 Science Revision Notes for quick help.

Revising this chapter can really help boost your overall score, as water is a topic that often comes up in the exams. Make your learning stress-free and fun with these notes!

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Access Class 7 Science Chapter 16 – Water: A Precious Resource

Water

Water is an inorganic chemical substance which is the main constituent of the hydrosphere. It is tasteless, transparent, odourless, and nearly colourless substance present in almost all known living organisms. It does not provide any calories or organic nutrients but still is vital for all known forms of life.

Forms of Water:

Water generally exists in three forms on the Earth;

Solid: In the form of ice present at the poles, at snow-covered mountains and glaciers.
Liquid: This form of water is generally present either on the surface in the water bodies like oceans, lakes, ponds, rivers etc. or underground where it seeps below the surface through soil that gets collected over non-porous rocks (aquifer) present belowground.
Gaseous: It includes the water vapour present in air.

Water Scarcity

The water present underground is considered as the purest form of water and most suitable for drinking purposes. Although there has been continuous depletion of the water column or the water table present belowground leading to water scarcity. The main reasons for this are as follow;

Due to increasing population, the open areas for water seepage belowground have decreased in many areas.
Due to the increase in the number of industries at many places, the utilization has also increased significantly for various industrial processes.
Failure of irrigation systems due to irregular rainfall at many agricultural places lead to use of groundwater.
The uneven distribution of rainfall at many places has also decreased the water table due to low rainfall.
Roots of trees often help in holding the run of water but due to deforestation the water flows to lower areas instead of seeping through soil and the water table decreases.

Preventing Water Scarcity

Sustainable water management: This can be achieved by using smart and efficient irrigation systems, water storages can be built for conservation.
Reclaimed Water: The pressure on groundwater can be decreased by rainwater harvesting and wastewater recycling. The run of rain water can also be trapped by digging pits at different places.
Sewage Treatments: The wastewater released from households or factories can be put into sewage treatment plants for their treatment and reuse. The sewage treatment will help in improving the water quality.
Awareness Programs: Awareness programs should be conducted to teach people about wastage of water and how to avoid it. And how the small and necessary actions can help in water scarcity in future.

Depletion of the Water table

Water depletion means water scarcity, which suggests that there is a lack of water. Water collected from underground is replenished by rainwater seepage. As long as we draw the same amount of water as is replenished by natural resources such as rain, the water table does not get affected.

Reasons Behind the Depletion of Water Table

There are several reasons behind the depletion of the Water Table;

Over-Pumping of Water: Groundwater is the water that flows through the ground and is stored. This groundwater can be collected either by drilling or digging wells or by pumping. Over-pumping of groundwater lowers the volume of groundwater. Excessive pumping in coastal areas may cause saltwater to shift inland and upland, resulting in saltwater pollution of the water supply.
Deforestation: Large-scale deforestation has taken place to accommodate the increasing population in order to produce food for them and provide space for industries. Overgrazing cattle has also killed a significant amount of vegetation. The green vegetation cover slows down the flow of water to the soil and increases the absorption of water by the soil. The cutting down of trees and plants, therefore, interferes with the natural mechanisms by which the seeping takes place and the groundwater is recharged and causes depletion.
Increased Industrialisation: All industries use water. Somewhere in the manufacturing process, almost anything that we use requires water. The number of industries is continually growing. The bulk of the water used in the industry is drawn from groundwater. This results in water being drained.

Groundwater as an Important Source of Water

What is Groundwater?

Groundwater is water accumulated under the earth's surface. Through the surface, the water seeps and the mud soaks it. By drilling or digging a well or by pumping, groundwater is procured. Overpumping of groundwater should not be done, as it affects the soil's salinity. It lowers the level of water and increases the soil's salinity. Groundwater is also cheaper than surface water, more convenient, and less prone to contamination.

Infiltration

Infiltration is a process in which the water on the surface seeps and enters the soil. The rate of infiltration is a measure of the rate at which rainfall or irrigation can be absorbed by the soil.

Aquifer

An aquifer is an underground layer of water-bearing permeable rock, a rock fracture or unconsolidated material (gravel, sand, or silt) from which groundwater can be extracted using a water well.

Water Availability and its Forms

Earth is made up of around 71% water but only a very small part of it is freshwater. Over ninety-seven percent of the water available is salt water that cannot be used for drinking. The remaining 3% is freshwater, of which 77% of the water is frozen in the form of ice caps, glaciers, etc and the groundwater makes up 22 % of the freshwater. The remaining one percent is contained in the river, lake, pond, streams, etc.,

Forms of Water

Water is available in all three states of matter i.e. solid, liquid, and gaseous. In liquid form, water is in its normal state. Ice is the solid-state of water and the gaseous state of water is a vapour. Water is one of the few substances which is heavier in a liquid state than in a solid-state.

Water Resources in India

In contrast to the rest of the world, India gets a lot of rainfall (rain and snow). Compared to the world's average of 700 mm, the average annual precipitation in India is 1170 mm.

Water Management

It is the task of planning, developing, distributing, and controlling the efficient use of water resources. Water supply pipes overflowing and a lot of water gushing out of the pipes is a waste of water. It is the duty of the civic authorities to avoid such wasting of precious water. Mismanagement or wastage can also take place at the level of individuals. We as an individual should also take care and should not wastewater.

Here are Some of the Ways of Managing Water

Drip Irrigation: Drip irrigation is a form of irrigation that, through a network of valves, pipes, tubing, and emitters, saves water and fertilizer by slowly dripping water into the roots of different crops, either on the soil surface or directly into the root region. This saves more water than the conventional irrigation method.
Water Harvesting: Rainwater harvesting is the accumulation and deposition of rainwater for reuse on-site, rather than allowing it to run off. Here, rainwater is stored for further use.
Cultivating Better Habits: To save water, there are numerous wise habits. We may use wise strategies to conserve water, as when washing clothes. Fixing taps that are leaky. While cleaning, hold the tap closed and take a short shower instead of a long one.

What are the Benefits of Referring to Vedantu’s Revision Notes for Class 7 Science Chapter 16 - Water: A Precious Resource?

Embark on a journey to understand the significance of water as a precious resource with Vedantu’s Revision Notes for Class 7 Science Chapter 16. These notes serve as a valuable compass, simplifying the complexities of water conservation and preservation.

1. Conceptual Summaries: Quickly grasp the importance of water as a resource, unraveling the key concepts and challenges it presents.

2. Simplified Understanding: Navigate through the complexities of water conservation, turning intricate concepts into easily understandable insights.

3. Last-Minute Water Wisdom: A reliable resource for last-minute exam preparations, ensuring you're well-versed in the vital aspects of water as a precious resource.

4. Enhanced Memory Retention: Solidify your understanding of crucial information about water conservation, reinforcing it for effective learning.

5. Strategic Exam Preparation: Guiding you with key points and tips specific to the chapter, ensuring you're well-prepared to tackle questions related to water preservation.

6. Time-Efficient Learning: Save time by accessing consolidated information, allowing you to focus on mastering the importance of water in our lives efficiently.

7. Focused Prioritization: Recognize the importance of specific topics and questions related to water conservation, giving you a targeted approach to your studies.

8. Real-World Water Connections: Understand the practical applications of water conservation through examples connecting abstract concepts to real-world scenarios.

9. Confidence-Boosting Water Wisdom: Approach your exams with confidence, knowing Vedantu's notes serve as a reliable companion in your journey to understanding and preserving water as a precious resource.

Conclusion

For an enhanced comprehension of this subject, NCERT - Class 7 Science Chapter 16 - Water: A Precious Resource, thoughtfully prepared by experienced educators at Vedantu, is your invaluable companion. These notes break down the complexities of Water: A Precious Resource into easily digestible sections, helping you grasp new concepts and navigate through questions effortlessly and quickly at the last minute as well. By immersing yourself in these notes, you not only prepare for your studies more efficiently but also develop a profound understanding of the subject matter.

FAQs on Water: a Precious Resource Class 7 Science Chapter 16 CBSE Notes - 2025-26

1. Why is water considered a precious resource for Class 7 students to understand?

Water is considered a precious resource because although the Earth is covered by about 71% water, only a very small fraction (about 0.006%) is available and fit for human use. All living organisms, including plants and animals, depend on this tiny amount of freshwater for survival, making its conservation crucial.

2. For a quick revision, what is the difference between groundwater and the water table?

For a quick summary, groundwater is the water that is found beneath the Earth's surface in the cracks and spaces in soil, sand, and rock. The water table is the upper level or surface of this zone of saturation. When you dig a well, the level at which you first find water is the water table.

3. How does the water cycle help in replenishing freshwater sources on Earth?

The water cycle is a continuous process that naturally replenishes freshwater. Water from oceans, rivers, and lakes evaporates, rises into the atmosphere, and cools to form clouds (condensation). This water then falls back to Earth as rain or snow (precipitation), refilling rivers and lakes and seeping into the ground to recharge groundwater, thus maintaining the supply of freshwater.

4. What are the main factors that cause the depletion of the water table, as explained in Chapter 16?

The primary factors responsible for the depletion of the water table are:

Increasing Population: More people require more water for drinking, cooking, and sanitation, increasing demand.
Industrialisation: Factories and industries use vast amounts of groundwater for their processes.
Agricultural Activities: A majority of farmers rely on groundwater for irrigation to meet the food demands of a growing population.
Deforestation: Trees help in water seepage into the ground. A lack of trees reduces the natural recharging of groundwater.

5. How does increasing deforestation worsen the problem of water scarcity?

Deforestation worsens water scarcity because forests play a key role in the water cycle. Tree roots create channels in the soil that allow rainwater to seep deep into the ground, effectively recharging the groundwater. When forests are cut down, the rainwater quickly runs off the surface, leading to less groundwater recharge and also causing soil erosion.

6. What is the core concept behind drip irrigation as a water management technique?

The core concept of drip irrigation is to conserve water by delivering it directly to the base of the plants, drop by drop. This method is highly efficient as it minimises water loss through evaporation and runoff, ensuring that almost all the water is used by the plants. It is a vital technique for water management in regions with water scarcity.

7. Why is rainwater harvesting a more sustainable long-term solution than simply digging more borewells?

Rainwater harvesting is more sustainable because it is a method of proactively recharging groundwater. It captures rainwater where it falls and directs it into the ground, raising the water table. In contrast, digging more borewells is a method of extraction that often takes out more water than is naturally replenished, leading to further depletion and long-term scarcity.

8. What is the essential role of water for plants?

Plants need water for several essential functions. They require water to absorb nutrients from the soil, for the process of photosynthesis to make their food, and to transport these nutrients throughout their structure. Without sufficient water, plants wilt and eventually die, which would disrupt the entire food chain and oxygen supply on Earth.

9. What are some key practices for a student to conserve water as a daily habit?

A student can adopt several simple habits to conserve water:

Turn off the tap immediately after use, especially while brushing teeth or washing hands.
Fix any leaking taps at home, as even a small drip wastes a lot of water.
Take shorter showers.
Reuse water where possible, for example, using the water from washing vegetables to water plants.