Rainwater Harvesting

Rainwater harvesting is the simple process or technology used to conserve rainwater by collecting, storing, conveying and purifying of rainwater that runs off from rooftops, parks, roads, open grounds, etc. for later use. Here, let us have a look at the diagram of rainwater harvesting system.

Rooftop Rainwater harvesting diagram

Rainwater harvesting

Explore more: How Can We Conserve Water?

All living things including plants, animals and human beings need water to live and to carry out different cellular activities.

Have you ever imagined a day without water?  

No, we have not and it is hard to imagine. We all use water for different kinds of day to day activities, such as cleaning, washing, bathing, cooking, drinking and other domestic and industrial uses.

Water is a precious, essential and an abiotic component of the ecosystem. Today we all are heading toward the scarcity of water, and this is mainly because of the lack of water conservation and pollution of water bodies. So, let us not waste a drop of water and start conserving water for further use.

Also read: Water

There are different methods used for conserving water; this article explains the rainwater harvesting system with a simple diagram.

Table of Contents

How to Harvest the Rainwater?

Rainwater harvesting systems consists of the following components:

  • Catchment- Used to collect and store the captured rainwater.
  • Conveyance system – It is used to transport the harvested water from the catchment to the recharge zone.
  • Flush- It is used to flush out the first spell of rain.
  • Filter – Used for filtering the collected rainwater and removing pollutants.
  • Tanks and the recharge structures: Used to store the filtered water which is ready to use.

The process of rainwater harvesting involves the collection and the storage of rainwater with the help of artificially designed systems that run off naturally or man-made catchment areas like- the rooftop, compounds, rock surface, hill slopes, artificially repaired impervious or semi-pervious land surface.

Several factors play a vital role in the amount of water harvested. Some of these factors are:

  • The quantum of runoff
  • Features of the catchments
  • Impact on the environment
  • Availability of the technology
  • The capacity of the storage tanks
  • Types of the roof, its slope and its materials
  • The frequency,  quantity  and the quality of the rainfall
  •  The speed and ease with which the rainwater penetrates through the subsoil to recharge the groundwater.

Why do we Harvest Rainwater?

The rainwater harvesting system is one of the best methods practised and followed to support the conservation of water. Today, scarcity of good quality water has become a significant cause of concern. However, rainwater, which is pure and of good quality, can be used for irrigation, washing, cleaning, bathing, cooking and also for other livestock requirements.

Advantages of Rainwater Harvesting

The benefits of the rainwater harvesting system are listed below.

  • Less cost.
  • Helps in reducing the water bill.
  • Decreases the demand for water.
  • Reduces the need for imported water.
  • Promotes both water and energy conservation.
  • Improves the quality and quantity of groundwater.
  • Does not require a filtration system for landscape irrigation.
  • This technology is relatively simple, easy to install and operate.
  • It reduces soil erosion, stormwater runoff, flooding, and pollution of surface water with fertilizers, pesticides, metals and other sediments.
  • It is an excellent source of water for landscape irrigation with no chemicals, dissolved salts and free from all minerals.

Also Read: Disappearing Act of Water

Disadvantages of Rainwater Harvesting

In addition to the great advantages, the rainwater harvesting system has a few disadvantages like unpredictable rainfall, unavailability of the proper storage system, etc.

Listed below are a few more disadvantages of the rainwater harvesting process.

  • Regular maintenance is required.
  • Requires some technical skills for installation.
  • Limited and no rainfall can limit the supply of rainwater.
  • If not installed correctly, it may attract mosquitoes and other waterborne diseases.
  • One of the significant drawbacks of the rainwater harvesting system is storage limits.

Know more about Rainwater Harvesting and other Biology related diagram concepts at BYJU’S Biology

Frequently Asked Questions


What do you understand by rainwater harvesting?

Rainwater harvesting is the process of accumulation and storage of rainwater for reuse rather than allowing it to runoff.


What are the different methods of rainwater harvesting?

The different methods of rainwater harvesting include:

  • Rooftop rainwater harvesting – The rooftop becomes the catchments, and the rainwater from the building and houses are collected. The components of the rooftop rainwater harvesting are:
    1. First, flush.
    2. Transportation.
    3. Catchment.
    4. Filter.
  • Surface runoff harvesting – It is the system that collects rainwater, which flows away as surface runoff. The runoff rainwater is caught and used to recharge aquifers by adopting appropriate techniques.

What is the importance of rainwater harvesting?

Rainwater harvesting is a sustainable process that helps in preserving water for future needs. Water scarcity is a major concern in today’s scenario. The process of rainwater harvesting is a good way to conserve water.


What are the advantages of rainwater harvesting?

The advantages of rainwater harvesting are:

  • It is cost-effective
  • Conserves water
  • A source of water for landscape irrigation
  • It is a simple method and easy to practice
  • It reduces soil erosion and pollution of water bodies due to fertilisers and pesticides

What are the factors affecting the amount of rainwater harvested?

The factors affecting the amount of rainwater harvested are:

  • Catchment features
  • Quantum of runoff
  • The capacity of storage tanks
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