Rainwater Harvesting

WHAT IS IT?

Rainwater harvesting is a simple system to collect, convey and store rainwater for directly used for irrigation purposes.

Two types of Rainwater harvesting are:
A.   Surface runoff harvesting
B.   Rooftop rainwater harvesting

Surface runoff harvesting – Surface runoff water harvesting is the collection, treatment or purification, and storing of stormwater for reuse. Surface runoff can be used for irrigation or recharging groundwater.

Rooftop rainwater harvesting - It is a system of catching rainwater where it falls. The rainwater is collected from the roof of a house/building. It can be stored in a tank and used later for irrigating kitchen gardens, etc.

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HOW SHOULD I MAKE IT?

Surface runoff harvesting

Land with at least 5% slope (~3°) can act as a catchment to generate runoff.
Runoff water is channelled towards the lowest point and collected in a small reservoir or a pond with earthen bunds or embankments which is built to collect runoff water. The tanks can be lined with Pond Liners / Geomembranes to reduce infiltration.
Catchment areas and storage areas should be located within a small distance of each other.
Tree species, shrubs or grass can be planted along the margin of the storage area to prevent silting of the reservoir.

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HOW SHOULD I MAKE IT?

Rooftop rainwater harvesting

Rainfall can be harvested from roofs, other paved platforms (verandah or yard).
Rainwater from the rooftop can be carried down through water pipes or drains to the storage/harvesting system.
A first flush device is used to discard the water received in the first shower. This is done to clear the silt and other materials deposited on the roof that gets washed away by the rain and to reduce the contamination of the water.
A filtration unit can be used to remove the particles and dirt before it enters the storage tank. This needs to be cleaned periodically.
The collected rainwater is stored in tanks or barrels. These can later be delivered through pipes (if the tank is located higher than the farm plot) or lifted through pumps (if the tank is located below ground).

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SETTING UP, OPERATION AND MAINTENANCE

The runoff or rainwater is received on the catchment area (e.g. sloping land surface, roof etc).
Then the water is channelled to the lowest point for collection in a reservoir or tank.
The collected water is later used for irrigation.

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WHAT'S IN IT FOR ME?

Increased agricultural production.
Reduced cropping risk.
Restoration of degraded land.
Slowing down of runoff during heavy rains.

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RAINWATER HARVESTING

WHAT IS IT?

HOW SHOULD I MAKE IT?

Surface runoff harvesting

HOW SHOULD I MAKE IT?

Rooftop rainwater harvesting

SETTING UP, OPERATION AND MAINTENANCE

WHAT'S IN IT FOR ME?