Content Writer-SME | Updated On - Aug 27, 2024
Rainwater Harvesting is the method of collection and storage of rainwater for water conservation purposes. It is used to collect rainwater that runs off from rooftops, parks, roads, open grounds, etc. for later use. Rainwater collection systems can be both simple and complex. Rain water can be used to irrigate gardens or catchments that supply drinking water since this process removes some organisms such as bacteria, viruses and parasites.
- Traditional rain water harvesting involves harvesting rainwater from a roof.
- Rooftop rainwater harvesting is one of the most widely used methods of collecting rainwater.
- In this method, the rainwater falling on the roof is collected and filtered before being stored in water tanks.
- The excess water is then diverted to wells to recharge groundwater.
What is Rainwater Harvesting?
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Water is an essential element that all living beings require to sustain life on Earth. If proper steps are not taken for water conservation, then along with the increasing population, water shortage will also become a major concern in the coming years. Rainwater harvesting is one of the successful strategies of water conservation which involves collection and storage of rainwater to reuse the water for various purposes.
- It is an old traditional practice that is used since ancient times.
- This method of conserving water is suitable for areas especially with an annual average rainfall of more than 400 mm.
- Rainwater harvesting is the practice of collecting water from rain for drinking, hygiene and other domestic purposes.
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| Chapter-Related Topics | ||
|---|---|---|
| Importance of Water | Scarcity of Water | Water Management |
| Potable Water | Forms of Water | Precipitation |
Importance of Rainwater Harvesting
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Rainwater Harvesting System is one of the oldest traditional practices to support water conservation. The scarcity of water in recent times has led to the popularity of rainwater harvesting from which the water can be used for irrigation, domestic chores, and other uses.
- It can be a permanent solution to the problem of the water crisis in different parts of the globe.
- Harvested rainwater is suitable for human consumption or agricultural purpose.
- It is an ideal solution for farmers who depend on monsoons for a consistent water supply.
- It can act up as an alternative to back up the main water supply, especially during dry spells.
- Rainwater harvesting solves water problems in regions that receive inconsistent rainfall throughout the year.
Here are some of the slogans that represents the importance of rainwater harvesting:
- “Harvest the rain, feed the earth”.
- “Harvest the rainwater, sow the seeds of life”.
- “Catch the rain, where it falls & when it falls”.
How to Harvest Rainwater?
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Rainwater can be collected from a building roof or other drainage surfaces like rock surfaces, hill slopes, etc. Then, the rainwater is channelled through gutters and pipes to a storage tank. The tank used to collect rainwater is made up of a variety of inert materials. Usually, the preferred location of the storage tank is underground, sheltered from daylight, as this minimizes algae growth in water.
A rainwater harvesting system consists of the following components:
- Catchment: It is used to collect and store rainwater.
- Conveyance System: It is used to transport the rainwater that is harvested from the catchment to the recharge zone.
- Flush: It is used to flush out the first spell of rain that is not collected.
- Filter: It is used to filter the collected rainwater and remove pollutants.
- Tanks: They are used to store filtered water that is ready to use immediately.
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Factors Affecting Rainwater Harvesting
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Artificially designed systems that naturally run off or man-made catchment areas such as the rooftop, hill slopes, and artificially repaired impervious land surfaces.are utilised for the storage of rainwater harvesting. The amount of harvested water is determined by following factors:
- Technology,
- Capacity of storage tanks,
- Types of roofs, slope, and materials used,
- Quantity, Frequency, and Quality of the rainfall,
- Quantum of runoff
- Features of catchments
- Speed and ease (rainwater penetrates through the subsoil to recharge the groundwater).
- Impacts on the environment.
Methods for Rainwater Harvesting
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There are several methods used for rainwater harvesting. The only difference in all these methods is the scale of the system. They all follow the same principles but differ in aesthetics and the effectiveness of the actual water conservation.
Rain Barrels:
They are the most common and familiar when it comes to rainwater harvesting. This method involves installing a barrel at a gutter downspout to collect rainwater. The actual barrel may be a recycled barrel or a new one.
Dry System:
A variation of a rain barrel setup involves a larger storage volume. The collection pipe dries after each rain as it empties directly into the top of the tank.
Wet System:
It involves locating the collection pipes underground to connect multiple downspouts from different gutters. The harvested water will fill the underground piping and the water will rise in the vertical pipes until it spills into the tank.
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Advantages of Rainwater Harvesting
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Rainwater Harvesting has proved to be very unique approach of water conservation in several aspects. Here are some of the advantages of rainwater harvesting listed below:
- Simple and easy method to store water even at home.
- Reduce stormwater runoff, flooding, soil erosion, and surface water pollution.
- Affordable & reduces the water bill.
- Limits the demand for water.
- Reduces the urge for importing water.
- Promotes the conservation of both water and energy.
- Quantitative & qualitative improvement of groundwater.
- Does not require a filtration system for landscape irrigation.
Disadvantages of Rainwater Harvesting
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Though there are numerous advantages of rainwater harvesting,the method has some disadvantages too which are listed below:
- Unpredictable rainfall, or limited and no rain can limit the supply of rainwater.
- Regular maintenance is required for the rainwater harvesting system.
- Technical skills are required for the installation of a harvesting system.
- It may attract mosquitoes and other waterborne diseases in case of an improper system.
- The limit of storage tanks is the most significant disadvantage of this process.
Things to Remember
- Rainwater Harvesting is the conservation of run-off rainwater by collecting, storing, conveying, and purifying the rainwater.
- It is very crucial to meet the global water crisis and the dry spell in various countries.
- A rainwater harvesting system involves the collection of rainwater in storage tanks that are usually placed underground.
- It is affected by various factors such as the quantity of rainfall, the technology used, storage capacity, etc.
- It is a cost-friendly method that is relatively easy to practice.
- The unpredictability of rainfall and maintenance of the system are the major drawbacks of rainwater harvesting.
Sample Questions
Ques. What is the importance of rainwater harvesting? (3 Marks)
Ans. Rainwater harvesting is an easy and economical way to deal with the water crisis throughout the world. The gradual falling levels of water are leading to a shortage of usable water. Rapid industrialization and disposal of chemical waste into water bodies are leading to the pollution of rivers, lakes, and ponds. This alarming situation needs a speedy solution. However, we can not increase the supply of fresh water on this planet. Thus, one way to deal with this crisis of water is to adopt rainwater harvesting.
Ques. What are rain barrels? Mention the pros and cons of this method of rainwater harvesting. (5 Marks)
Ans. The method of using rain barrels in rainwater harvesting is the most common and one that many people are familiar with. This method involves installing a barrel at a gutter downspout to collect rainwater. The barrel may be a recycled barrel or a new commercially available rain barrel.
Pros of Rain Barrel
- It can be easily implemented by anyone at any residence.
- Rain barrels are easily available in any community or at various stores and websites.
- They do not occupy much space so they can fit into any situation.
Cons of Rain Barrel
- The capacity of the barrel is generally only 50 to 100 gallons.
- The barrel overflows and wastes collection opportunities.
Ques. Why do we need to harvest rainwater? (3 Marks)
Ans. The modern rainwater harvesting systems are properly managed and maintained and thus are completely safe and yield good quality water. Using this rainwater, we can increase water availability and reduce the demand for water from the water supply network through its subsequent use for non-potable applications. The harvested rainwater can be used for several applications such as toilet flushing, irrigation, car washing, etc. It also helps to increase soil moisture levels for urban greenery, mitigate urban flooding and improve the quality of groundwater.
Ques. List the different methods of rainwater harvesting. (3 Marks)
Ans. There are two main methods of rainwater harvesting which are as follows:
- Rooftop Rainwater Harvesting: In this method, the rooftop becomes the drainage area, and the rainwater from the building and houses is collected. The components of rooftop rainwater harvesting are as follows:
- Flush
- Transportation
- Catchment
- Filter
- Surface Runoff Harvesting: This system involves the collection of rainwater, which is used to recharge aquifers by adopting appropriate techniques.
Ques. Mention the advantages of rainwater harvesting. (3 Marks)
Ans. The advantages of rainwater harvesting are as follows:
- Rainwater harvesting is cost-effective.
- It is a simple and easy method to adopt and practice.
- It is one of the best methods to conserve water.
- It is a source of water for landscape irrigation.
- It helps to reduce soil erosion and pollution of water bodies due to fertilizers and pesticides.
Ques. What are the uses of harvested rainwater? (3 Marks)
Ans. The various uses of harvested rainwater are:
- It can be used to water the lawn and gardens:
- It can be connected to an irrigation/sprinkler system.
- To wash vehicles.
- To give baths to pets.
- To refill the fountains and fish ponds.
- Can be used for all indoor non-potable fixtures (toilets and clothes washers).
Ques. What is Surface Runoff Harvesting? (3 Marks)
Ans. Surface runoff harvesting is the most suitable rainwater harvesting method in urban areas. In this method, the rainwater flows away and can be stored for future use. The water thus collected can be used to provide water for farming, cattle, and also for general domestic use. Surface water can be stored by redirecting the flow of creeks and streams into reservoirs on the surface or underground.
Ques. Where is rainwater usually stored? (2 Marks)
Ans. The rainwater is usually stored in a tank typically from rooftops via pipes. It is sometimes called a rain barrel in North America in reference to smaller tanks, or a water butt in the UK. Rainwater tanks are used for the collection and maintenance of harvested rain.
Ques. How does rainwater harvesting help farmers? (3 Marks)
Ans. A bad monsoon leads to a low crop yield and food shortage. The Indian Subcontinent and Africa face acute water crises during the summer months. During this span, the farmers are the most affected because they do not get sufficient water for their fields. Thus, rainwater harvesting is an ideal solution for farmers who depend on the monsoon for a consistent water supply. They can use the stored rainwater in case of bad monsoon conditions.
Ques. How does rainwater harvesting help to recharge groundwater? (3 Marks)
Ans. Rainwater Harvesting involves the storage of rainwater which can be used directly and can also be utilized to revitalize the ground-level water and improve its quality. Rainwater harvesting also helps to raise the level of groundwater which then can be easily accessible. When this water is fed into the ground-level wells and tube well, they are prevented from drying up. This eventually increases soil fertility. It checks the surface runoff of water and reduces soil erosion.
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