Greenprint your home workshop: Water and you, what it means to be sustainable for water. Avinash Krishnamurthy of Biome explains the importance of water conservation inside the home - why, what and how.
Water and you
What you do makes up the bigger picture
How much water do I use ?
Real Consumption range :
from 50 to 300 liters per person per day
National Town planning Norms :
Urban : 135 Lpcd
Rural (Karnataka) : 55 Lpcd
What about the rain ? : Local hydrologic cycle
Site : 30 * 40 (Area 110 sqm)
Annual rainfall on it in B’lore : 106700 Litres
Runoff : 10%
10670 Litres / annum
85360 Litres / annum
Difference :74690 Litres / annum
Who should manage this excess ?
Let’s look at the numbers more closely…..
Water falling on the roof
(30 * 40 site)
10 mm (small shower)
30 mm (Average shower)
60mm (heavy shower)
Annually in Bangalore – 970mm
4 member household, @ 135 lpcd needs 540 litres / day
i.e. in Bangalore there is enough rain falling for 161 days of a family
For nearly 5.5 months of the year
Almost 50% of a household’s needs !!!
Can we capture this store it or recharge it into our borewells
(or can we do rainwater harvesting) ?
Most important principles of RWH – 2:
Rainfall pattern & Geology
Rainfall more evenly spread better
Direct storage and Use.
Geology and aquifer regime to be
suitable for recharge. Recharge to
be designed for local conditions.
Thumb rule : Open wells good in
deccan plateau. Depth of well
necessary different in different
place. 20ft minimum thumb rule.
RAIN WATER HARVESTING FOR HOUSEHOLDS : Quantity, Bangalore
Tank Size Study
10000 15000 20000 25000 30000 35000 40000 45000
Household Rainwater Harvesting:
Runoff for a Runoff
Most important principles of RWH – 1:
Catchment and type of harvesting
STORAGE : SUMPS, RAIN BARRELS (etc)
NOT-SO CLEAN CATCHMENTS
RECHARGE : OPEN WELL, DIRECT BOREWELL
….So how clean is Rainwater ?....
A Bucket of Rainwater in
Kurubarakunte village, Bangalore
Rainwater in a Glass
Cauvery water in a Glass
Which is which ?
….Really as clean as your roof (catchment) is…
Clean Rainwater comes from
Catchments that are clean
– Roof tops are the cleanest Catchment.
Keep your roof clean :
No junking, no pets, no crackers, no holi,
No chemical pesticides/fertilisers on the roof
Managing Rainwater Quality : rainwater picks up contaminants from :
1. Urban pollution – First Rain separation
2. Contamination from the catchment – Catchment management, Pre-filtering
3. Rainwater has low TDS, low Hardness and low all other counts !!!
Rainwater, for drinking will need Point of Use treatment for Bacterial
Eg: SODIS, Good rolling boil, Aquaguard etc.
Site Selection for Infiltration
Many factors affect the suitability of a site as an infiltration facility for the
disposal of stormwater. Among these, the following are most important:
• Depth to groundwater
• Surface soil type
• Underlying soil type
• Vegetation cover of the infiltrating surface
• The uses of the infiltrating surfaces
• The ratio of tributary impervious surface to the infiltrating surface
Building bye-laws in Bangalore
• ALL buildings with roof area more than 100
• 20 litres for every sq. mt. (storage or recharge)
• 60 litres for every square metre for more than
5000 square metre plot size
Demand – the heart of the scarcity problem
What else can you do?
Reuse Waste Water (eg: Grey for flushing,
Treated black/grey for irrigation)
And use the treated waste water to irrigate
Your roof farm that produces food
Water harvesting and grey water reuse in a house