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Rain Water Harvesting 
Why & How
Rainwater harvesting 
can be 
harvested from the 
following surfaces:
Rooftops 
If buildings with impervious roofs are already in place, the 
catchment area is effectively available free of charge and they 
provide a supply at the point of consumption. 
Paved and unpaved areas i.e., landscapes, open fields, parks, 
storm water drains, roads and pavements and other open 
areas can be effectively used to harvest the runoff. The main 
advantage in using ground as collecting surface is that water 
can be collected from a larger area. This is particularly 
advantageous in areas of low rainfall.
Water bodies: 
The potential of lakes, tanks and ponds to store rainwater is 
immense. The harvested rainwater can not only be used to 
meet water requirements of the city, it also recharges 
groundwater aquifers.
Storm water 
drains: 
Most of the residential colonies have proper network of 
storm water drains. If maintained neatly, these offer a simple 
and cost effective means for harvesting rainwater.
Whether to store 
rainwater or use it for 
recharge: 
The decision whether to store or recharge water depends on 
the rainfall pattern and the potential to do so, in a particular 
region. The sub-surface geology also plays an important role 
in making this decision.
For example: 
Delhi, Rajasthan and Gujarat where the total annual rainfall 
occurs during 3 or 4 months, are examples of places where 
groundwater recharge is usually practiced. In places like 
Kerala, Mizoram, Tamil Nadu and Bangalore where rain falls 
throughout the year barring a few dry periods, one can 
depend on a small sized tank for storing rainwater, since the 
period between two spells of rain is short. Wherever sub-strata 
is impermeable recharging will not be feasible. Hence, 
it would be ideal to opt for storage.
In places where the groundwater is saline or not of potable 
standards, the alternate system could be that of storing 
rainwater. 
Beyond generalizations, it is the requirement that governs the 
choice of water harvesting technique. For example, in 
Ahmadabad, which has limited number of rainy days as that 
of Delhi, traditional rainwater harvesting tanks, known as 
tankas, are used to store rainwater even today in residential 
areas, temples and hotels.
Know more about Water Conservation on 
WaterConsumer.org.

More Related Content

Rainwater Harvesting

  • 2. Rainwater harvesting can be harvested from the following surfaces:
  • 3. Rooftops If buildings with impervious roofs are already in place, the catchment area is effectively available free of charge and they provide a supply at the point of consumption. Paved and unpaved areas i.e., landscapes, open fields, parks, storm water drains, roads and pavements and other open areas can be effectively used to harvest the runoff. The main advantage in using ground as collecting surface is that water can be collected from a larger area. This is particularly advantageous in areas of low rainfall.
  • 4. Water bodies: The potential of lakes, tanks and ponds to store rainwater is immense. The harvested rainwater can not only be used to meet water requirements of the city, it also recharges groundwater aquifers.
  • 5. Storm water drains: Most of the residential colonies have proper network of storm water drains. If maintained neatly, these offer a simple and cost effective means for harvesting rainwater.
  • 6. Whether to store rainwater or use it for recharge: The decision whether to store or recharge water depends on the rainfall pattern and the potential to do so, in a particular region. The sub-surface geology also plays an important role in making this decision.
  • 7. For example: Delhi, Rajasthan and Gujarat where the total annual rainfall occurs during 3 or 4 months, are examples of places where groundwater recharge is usually practiced. In places like Kerala, Mizoram, Tamil Nadu and Bangalore where rain falls throughout the year barring a few dry periods, one can depend on a small sized tank for storing rainwater, since the period between two spells of rain is short. Wherever sub-strata is impermeable recharging will not be feasible. Hence, it would be ideal to opt for storage.
  • 8. In places where the groundwater is saline or not of potable standards, the alternate system could be that of storing rainwater. Beyond generalizations, it is the requirement that governs the choice of water harvesting technique. For example, in Ahmadabad, which has limited number of rainy days as that of Delhi, traditional rainwater harvesting tanks, known as tankas, are used to store rainwater even today in residential areas, temples and hotels.
  • 9. Know more about Water Conservation on WaterConsumer.org.