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Catch the Rain where it Falls

Catch the Rain where it Falls

In cities, buildings are usually constructed with rooftops of Reinforced Cement Concrete (RCC) or Mangalore Tiles. Rooftop rainwater usually flows into storm water drains outside the plot area. As roofs are built with hard material, large quantities of rainwater will runoff and losses due to evaporation and percolation is minimal.

“Catch the rain where it falls” – allow the rooftop rainwater through a filter into your tank. In your building you have the roof, you have the down water pipes and also a tank to store water. Just interconnect two or three down water pipes and attach a rainwater filter before allowing the rainwater into your tank. You will get pure water at your doorstep.

Explaining Rainwater Harvesting

It is a simple intervention to collect rainwater. The first and easiest approach to rooftop rainwater harvesting. Collect the roof water, which is already flowing through a down water pipe, attach a filter at the end of the pipe to separate the dirt, dust, bird droppings and leaves and divert the filtered rainwater into a storage unit such as a tank/sump. This can give you sustained water supply during the rainy season.

The excess water which overflows from the sump or tank can be used to recharge the groundwater through a pre-cast cement ring open well. When rainwater is discharged into this well, it slowly percolates into the groundwater table and can be withdrawn through a borewell or an open well. These two systems can provide water supply throughout the year.

Simple questions about rainwater harvesting answered by the expert.

How do I fix rainwater harvest to my house?

RWH is a simple process to retrofit your house. You may follow the steps given below:

  • Select one or two down pipes carrying most of the rainwater from your roof.
  • Interconnect them
  • Add a wall mounted rainwater filter to the end of the pipe
  • Connect the filtered water outlet of the filter to your underground water tank
I get water from my local corporation, why should I do rainwater harvesting?

Supply from the corporation is limited. If you can do rainwater harvesting, then you do not have to depend on just water from your corporation. This allows for more houses to receive the corporation water.

What are the costs involved in doing rainwater harvest?

Rainwater harvesting system set-up in Bangalore may cost between Rs 10,000 – Rs 50,000 depending on the site conditions. The cost varies from site to site and in order to compute the costs you can consider the following heads

  • Cost of tank or sump – Rs 6-10 per litre
  • Cost RWH wall mounted filter for domestic application – Rs 4000 to Rs 12000 per filter for around 100 sqm or 1000 sq ft roof area.
  • Cost of cement ring well (of 3 ft diameter and 20 ft depth) for ground water recharge – Rs 15000
  • Cost of pipes and fitting at market rate
  • Add labour as applicable.

This blog is extracted from the book Raindrops on Roof Top by A R Shivakumar

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