Guide on Rain Water Harvesting
                     RAIN WATER HARVESTING
What is 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.
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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 remove 
pollutants
• Tanks and the recharge structures: Used to store the filtered 
water which is ready to use
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The process of 
rainwater harvesting
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.
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Key factors in water 
harvesting
• 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
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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.
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Advantages of 
Rainwater Harvesting
• 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.
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Advantages of Rainwater 
Harvesting cont.
• 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 and dissolved salts and free from all 
minerals.
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Disadvantages of 
Rainwater Harvesting
• Regular Maintenance is required.
• Requires some technical skills for installation.
• Limited and no rainfall can limit the supply of Rainwater.
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Disadvantages of 
Rainwater Harvesting 
cont.
• 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.
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Different methods of 
rainwater harvesting
The different methods of rainwater harvesting include:
• Rooftop rainwater harvesting.
• Surface runoff harvesting.
• First, flush.
• Transportation.
• Catchment.
• Filter.
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