The IHB Guide: Monsoon is here, time to get responsible with rain water harvesting!

The monsoon season is upon us to bring respite from the sweltering heat (phew!) and we couldn’t be more thankful. Time to do our bit to contribute to the environment (we are dwellers of the Garden City after all), in the form of a fun and easy-to-do DIY project at home.

What is rainwater harvesting?

There is no rocket science involved. Rainwater harvesting is the simple process of collecting, filtering and using rain water. The three forms of rainwater harvesting are based on how you collect the water, depending on your need or convenience:

  • Refilling borewells
  • Topping-up ground water sources
  • Setting-up your own collection units on your rooftops, porticos or any other vantage point.

Why the need?

With many of the water sources of the yesteryears drying up, Bangalore’s entire population (urban and rural) has come to depend on Cauvery water. Karnataka can draw only 682.5 million liters a day against the 1,400 million liters per day that the city needs!

How do we benefit?

  • Easily accessible water
  • Low set-up, construction & maintenance costs
  • Higher sustainability
  • Highly adaptable to different landscapes

Did you know?

Rainwater harvesters can catch up to 80% of the annual rain that falls in the catchment area of their homes.

How do we begin?

It’s pretty simple, really. Below is a four-step DIY induction for beginners:

  1. Catchment: The surface that receives direct rainfall is the catchment area for your project. It may be your terrace, backyard, a cemented area etc.
  2. Transportation: Rainwater from the catchment should be directed to the collection unit through pipes or drains. This step depends on the force of gravity, for transporting the water. The transporting pipes should be UV resistant (ISI HDPE/PVC pipes) and of the required capacity. Water from sloping roofs could be caught through existing gutters and downward sloping pipes. At terraces, the mouths of each drain should have wire mesh to restrict floating material from passing.
  3. First Flush: First flush is a device used to flush off the water received in the first shower. The first shower of rains needs to be flushed-out to avoid contamination. It will also help in cleaning of silt and other material deposited in the catchment areas, during the dry months. Provisions for first rain separators should be made at the outlet of each drainpipe.
  4. Filter: Though a complete DIY technique requires you to make a natural filter using sand, gravel, pebbles, etc., a variety of readymade filters are available in the market that are both tried & tested and reasonable. IHB recommends the Rain Tap Pop-up filter, invented and patented by the city’s Rain catcher himself (the man who never pays for water), A.R. Shivakumar.

Did You Know?

The roof of an average sized home (40ft X 25ft) can catch up to 22271.25 litres of water with just one hour of moderate rainfall

What do I need?

Click here for a list of trained and certified rainwater harvesting contractors who can guide you with your set-up and equipment purchase.

The dos and don’ts:

Pick the right location

  • Place collection units right below a downward outlet/pipe
  • Never place collection units near utility services or septic tanks

Use screens

  • Sieve out leaves and other debris with a screen or mesh
  • Do not leave the opening of the collection unit uncovered at any point

Filtration technique

  • Use a tried and tested filter to reduce contaminants
  • Never drink untested or unfiltered water

Set-up a drainage

  • Install an overflow unit to collect excess water

Help our city. Do your part. Be a Bangalorean. xx

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