Tuesday, 1 April 2014



1.      What is Rainwater Harvesting (RWH)?
RWH is the process of collection of rainwater and storing it for future use.

2.      How is RWH done?
Rainwater is directly collected from the roof or open space and filtered before storing or recharging to the ground.

3.      What are the methods of RWH?
There are three methods of RWH – Roof top RWH, Open space RWH and Ground Water Recharge.

4.      What are the advantages of RWH?
Rainwater Harvesting has many advantages:
·         Augments the existing water supply
·         Reduces water bill
·         Reduces effect of draught and flood
·         Improves ground water availability and quality
·         Environment - friendly technique

5.      Who can do RWH?
Any individual or institution can do rainwater harvesting. If you are planning to build a house, you can incorporate in the planning stage itself. If you have one already, you can retrofit rainwater harvesting.

6.      What is the cost of RWH?
The cost of RWH depends on quantity of the rainwater collected and the purposes for which it is required.   It varies from Rs. 2,000/- to Rs. 50,000/- for residential buildings.

7.      What are the space requirements?
For a residential building, a tank / sump of 5000 - 10000 ltr (5ft. x 6ft. x 6ft. - 10ft. x 6ft. x 6ft.) needs to be built for storing the rainwater. Bigger the storage facility, longer will be the availability of rainwater.

8.      How does RWH benefit me?
The benefits of RWH:
·         Immediate fresh water availability
·         Reduces water bill
·         Reduced dependence on conventional water supply
·         Better living environment

9.      What about the quality of water?
Rainwater is the primary source and is purest form of water. You can collect rainwater and use it for drinking purposes. However, precautions need to be taken, to keep the water free from contaminants on the roof, open space, during channeling and storage.

10.  Who can help me in RWH?
With a little guidance, you can do RWH on your own. In case you need help you can contact an architect or an engineer, who has knowledge of RWH.  There are also agencies and consultants who take up RWH on turnkey basis. You can contact BWSSB & KSCST RWH Helpdesks at : 080 23341652, 080 23348848, 080 26653666, www.kscst.iisc.ernet.in/rwh.html

11.  How long can I store the collected water?
Since water does not get contaminated when it is stored away from sunlight and air, you can store water that’s free from impurities up to six months.

12.  How can I use the harvested rainwater?
Rainwater can be used practically for all purposes.

13.  What is the approximate quantity of rainwater I can harvest?
In a 100 sq. mtr area with annual rainfall of 1000 mm (Bangalore rainfall), you can collect one lakh liters of rainwater.

14.  What could be the adverse effects of RWH?
If proper care is not taken, the following adverse effects could result –
(a) Contamination of water, if the rooftop is not clean, (b) Water logging, if ground water is not recharged properly and (c) Flooding of roofs, if filters are not properly designed and cleaned frequently.

15.  Is it one time or recurring investment?
RWH system is one-time investment. The storage facility is the single most expensive component of RWH. Recurring expenditure are cost of cleaning the filter and pumping of water.

16.  Can rainwater be harvested in industries / institutions and multistoried buildings?
Yes, since the roof area and open area available are bigger, rainwater can be harvested on a large scale and the amount of savings will be huge. In multistoried buildings, it has to be a community initiative.

17.  Flat or sloping roof - which is better suited for RWH?
Both types of roofs are suitable for RWH.

18. Can the harvested rainwater be used for recharge of groundwater (Borewell / open well)?
Yes, it can be done. In fact, many dried wells have got a new lease of life after RWH.

19.  Can a family live entirely only on rainwater?
Yes, it is possible. In fact, there are many households which do not depend on public water supply system.

20.  Do I need to take any permission from any department or neighbours to install a RWH system for Ground Water Recharge?
No permission is required.

21.  Can sewage or any other water pollute ground water?
If proper care is not taken, leaking sewage pipes, nearby toilet soak pits and industrial effluents can pollute groundwater.

22. Can I plan Rainwater harvesting to my building on my own?
     Yes, go to link: http://rwh-advisor.info  an App developed by KSCST and UNESCO, which is both available on Google play store and web.

23. I need to see the RWH models practically, where should I walk-in?
     We have established in collaboration with Bangalore Water Supply and Sewerage Board  (BWSSB) “Sir M Visvevaraya Rainwater Harvesting Theme Park” in 40th cross, 8th Main, 5th Block, Jayanagar, Bengaluru. Experts here will demonstrate and advise on RWH. Contact @ 08026653666 / 08023341652

 24. Where Can I get more information on water, energy and environment?

     Visit the Blog link http://rainmanspeaks.blogspot.in you will get lots of write-ups with Images and Videos.

AR Shivakumar