Rain Water Harvesting


Many parts of India receive enough rainfall to have clean and drinkable water throughout the year. However, water management in India woefully lacks the capability to store and distribute water properly. Rapid urbanization has accelerated the demand for water. At the cause of depleting rainfall and groundwater levels. 

It’s up to the individual citizens to help themselves. Rooftop rainwater harvesting is one solution that gives power in the hands of individual house owners to produce water for their own requirements. Interestingly, a mere 100 cm rain in a year on a 100 square feet roof gives full year’s drinking and cooking water needs of a 5 people family.    

Water Scarcity in India

India has the second-largest population in the world. According to the World Bank, India has taken important steps to reduce poverty but the number of people who live in poverty is still highly disproportionate to the number of people who are middle – income, with a combined rate of over 52% of both rural and urban poor. India has only 4% of the world’s water resources despite a population of over 1.35 billion people.

The water dearth is mostly man-made due to excess population growth and mismanagement of water resources.

Water Scarcity in India

Some of major reasons of water scarcity are:

  • Inefficient use of water for agriculture.
  • Reduction in traditional water recharging areas.
  • Sewage and waste-water drainage into traditional water bodies.
  • Lack of on-time de-silting operations in large water bodies that can increase water storage capacity during monsoon.
  • Lack of efficient water management and distribution of water between urban consumers, the agriculture sector, and industry.

The water scarcity has impacted India severely as is evident from the fact that nearly 50% of India is grappling with drought-like conditions prevailing particularly in western and southern states.

Some of the long term impacts are as below:

  • Reduction in economic growth.
  • Unavailability of water for irrigation, leading to poor production & agricultural crisis.
  • Shortage in the power supply.
  • Scarcity of drinking water.
  • Climate change.

Water Scarcity – A Challenge

Root Causes & Facts

Uncertain Rainfall & Change in Rainfall Pattern

In India, the actual rainfall in the last decade has shrunk in number of rainy days both in the case of pre-monsoon & four-month period of monsoon. This indicates the increase in the intensity of rainfall with a decrease in actual rainfall days which further affects the percolation rate, causing short-duration floods in rivers / nallahs.

Dependency on Ground Water Resources

The Dependency on Groundwater for irrigation, drinking & industrial use has increased significantly in past decades as it is the only available & convenient alternative in draught & empty reservoirs. Further, this has affected the groundwater levels in many parts of the country which have gone down drastically as it is the only alternative.

Whatever we are taking out, not giving back to the nature

Lack of awareness, unavailability of proper resources, skilled applicators have created the situation of whatever we are taking out from nature, not giving back to nature.

Depleting Ground Water Levels in India

The groundwater table in some areas is falling at the rate of one meter per year and rising in some other areas at the same rate. The no. of wells and bore wells increased fivefold to more than 175 lakh during the past fifty years. More than 80% of rural and 50% of urban, industrial, and irrigation water requirements are met from groundwater.

Challenges in Coastal areas

Serious environmental problems to the coastal subsurface water system, due to global warming-sea level rise, increasing salinity due to seawater intrusion is becoming major problems along coastal regions of India.

Conserving rain water – A solution to self sufficiency

The only solution is to return back what we take from the ground. “Rain water harvesting” is a very effective method. Rain water harvesting provides self-sufficiency to capture rain water, store it, and use it. It is as simple as that. Collect the rain water falling on housetops slab or roof, collection ponds, lakes, open areas with natural grading. Rain water is naturally pure groundwater that could be salty or brackish.

What is Rain Water Harvesting?

Rain Water Harvesting is collecting the run-off from a structure or other impervious surface in order to store it for later use. This involves harvesting the rain from a roof. The rain will collect gutters that channel the water into downspouts and then into some sort of storage vessel. Rain water collection systems can be as simple as rain in a rain barrel or as elaborate as harvesting rain water into a large tank for storing water to supply your entire household demand.  

The rain water harvesting is becoming a viable alternative for supplying our households and businesses with water. There are many countries such as Germany and Australia where rain water harvesting is the norm. Due to the green building movement, you will be seeing rain water harvesting systems become more popular in America.

The collection of rain water is known by many names throughout the world. It ranges from rain water collection to rain water harvesting to rain water catchment. In addition, terms such as roof water collection or rooftop water collection are also used in other countries. It is the term used to indicate the collection and storage of rain water used for humans, animals, plant needs, and recharge groundwater table also. It involves the collection used and storage of rain water at the surface or in the sub-surface aquifer before it is lost as surface runoff.

We believe that rain water harvesting is a viable technology in an urban setting. All that is necessary to take advantage of rain water harvesting is to capture the free water falling on your roof and direct it to a rain water storage tank. By doing this, you can take control of your water supply and replace all or at least a considerable portion of your water needs. Rain water harvesting system can be configured to supply your whole house and/or your landscape needs.

Understanding “Roof Top Rain Water Harvesting”

  • Collect water from the rooftop.
  • Draw it down from pipes.
  • Filter the water.
  • Store in a sump/tank for later use.
  • Charge the groundwater table through a soak pit.
  • Lead the rain water into a well to increase groundwater content.
Roof Top Rain Water Harvesting

What are the Benefits of Roof Top Rain Water Harvesting?


  • Reduces water bills
  • Reduced water demand – water supply utility saves money on treatment & pumping
  • It reduces the cost of infrastructure necessary for water supply


  • If water is hard, adding soft rain water improves water quality
  • Improves groundwater situation
  • Reduces demand for water at the city or village level
  • Storing water under-ground is environment friendly
  • It reduces flood hazard
  • Reduces soil erosion

Benefits to house owners

  • Simple, cost-effective, easy to construct and maintain
  • Viable in urban and rural areas, slums, low-income housing, apartments
  • No land is wasted for storage purpose
  • No population displacement is involved

Need of Rain Water Harvesting

  • To overcome the shortage of surface water to meet our demands.
  • To arrest the decline in groundwater levels.
  • To enhance the availability of groundwater at a specific place & time and utilize rain water for sustainable development.
  • To accrue infiltration of rain water in the subsoil, because the infiltration of rain water has decreased drastically in urban areas due to paving of open area.
  • To improve groundwater quality by dilution.
  • To increase agriculture production.

What are the uses of Collected Rain Water?

Here are some ideas for specific uses of collected rain water:

  • Drinking and cooking
  • Bathing and laundry
  • Flushing toilets
  • Watering lawns, garden, and houseplants
  • Composting
  • Water for wildlife, pets or livestock
  • Outdoor ponds and water features
  • Rinsing vegetables
  • Washing vehicles and equipment
  • Fire protection
  • Cleaning the exterior of buildings
  • Refill your fountains and fish ponds
  • Refill your swimming pool
  • Replace the use of tap water with rain water to wash your driveways and sidewalks
  • Use it for industrial process instead of municipally treated water

What are the different methods to collect Rain Water?

The different methods to collect rain water are as below:

  • Rain Barrels
  • Dry Systems
  • Wet Systems
  • Green Roof
  • Rain water collection system
  • Rain water chain
  • Rain water tarp
  • Rain water gardens
  • Plastic – lined pond
  • Install a cistern to help water to your garden
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