Rainwater harvesting Brochure for Apartments

1. Cooking and
Drinking
after Boiling or
Filtering
Cleaning
and Laundry
Bathing
Cleaning
Vessels
Storage (tank)
Water Pumps
Watering Garden
Washing Car
Filter
First Rain Separator
Conveyance
Catchment
RainwaterHarvestingin apartments Useofrooftopharvestedwaterin apartment
1 2
Overflow pipe to
recharge well/ sump/
storm water drain
Ground level
Platform
Filter
75/90 mm
diameter PVC
pipe
Inlet to tank
First rain
separator
PVC gate
valve
Rooftop
rain water
3 4 5 6
Sample Apartmentof20flatsof7000sqftplot
Breakupof Area
Different Areas Area WaterfromOneRain(30
mm)
Roof area
Paved area
Total area
463 sqm
151 sqm
614 sqm
12,500 liters
3,000 liters
15,500 liters
Rooftop Harvesting
in Apartments
Recharge wells in
Apartments
Urban flooding
Groundwater Depletion
Rainwater Harvesting helps
1. To recharge groundwater
2. To reduce flooding
TwinProblemin apartments
WhatisRechargeWell
Rooftop
Rooftop
Paved Area
Paved Area
Well
Lake
Recharge Well
Storm Water Drain
Fractured Zone
Bed Rock
Bore Wells
Top Soil
Unconfined Shallow Aquifer
Deep
Aquifers
Ground Water
Recharge
Gutter
Storage
Paved area
Roof-top runoff
Paved area
runoff to
recharge well
Recharge
Well
Overflow
from
storage
Plan of Apartment
WHATISRAINWATERHarvesting?
Rainwater Harvesting (RWH) is the process of collecting and
storing rainwater falling on our rooftops for future use.
The surface runoff from the paved and unpaved areas can
be used for groundwater recharge through recharge wells.
WaterfromRainbarrelorsump
Water can be used for cleaning, washing and bathing. It can be used
for cooking and drinking, after boiling or after passing through an
appropriate drinking water filter.
ComponentsofrooftopRainwaterHarvesting
1. Catchment: The area where rain falls and the runoff from which
it is collected, stored and used – in this case it is a rooftop.
2. Conveyance: In the case of buildings with flat roofs, downpipes
carry rainwater falling on the rooftop. In the case of sloped roofs,
gutters can do the job. Gutters can be of any material like PVC,
polycarbonate or galvanized iron; you can select the material
depending on cost, durability and aesthetics.
3. First Rain separator: Allowed to wash the rooftop and there-
fore ensures no accidental debris or dust is washed into the RWH
storage from your clean catchment.
4. Filter: To Filter the water to free from physical impurities before
entering into the storage.
5. Storage: To store rainwater for end uses.
1. Rooftop runoff to storage like Rain Barrel or Sump. This stored
water helps apartment for end uses
2. Paved area runoff to Recharge well. This helps to channel the
run-off into the aquifer to recharge groundwater
A recharge well is a big hole in the ground through which rainwater
goes into the earth and becomes part of groundwater. Over a
period of time recharge wells can start yielding water. If the wells
has water, this water should be tested and used appropriately
based on water quality. Wells with water can also be used as
recharge wells.

2. 150 lts per
person
Apartment of 56
occupants
Per day demand:
8,400 lts per day
Rooftop
Catchment = 463 sqm
Water can be harvested=
12,500 lts
meets around
1 to 2 days daily demand
Paved area = 151 Sqm
4,000 lts
20 Feet
Rooftop
runoff
Storage tank
Recharge
well
3 Feet
RainwaterHarvestingfor
Apartments
Maintenanceofrooftopharvesting
1. Clean the filter medium twice a year, before and after the rainy
season, by washing the jelly and charcoal.
2. The inlet of rainwater downpipes with grating should be cleaned
regularly to avoid stagnation of Rainwater on the terrace.
7 8 9 10
Howmuchdoes a Rechargewellcost
Howmuchwatercanbeharvested
Recharge Well
3 Feet
20 Feet
BestPracticesforWaterManagement
Terrace cleaning has
to be done without any
chemical or soap water.
Terrace garden, isolated
from the catchment.
Clean terrace
Catchment area
Terrace
wash pipe
Pipe to
sump
Rooftop Harvesting
1. 12,500 liters of rainwater can be harvested from one rain from roof-
top area of 463 sqm,
2. This can meet around 1 to 2 days of daily fresh water demand
3. This can be stored in a underground sump or in a Rain barrel
Recharge Well
1. 3,000 litres of surface runoff is generated from the road and paved
area of 151 sq m
2. One recharge well of 3 feet dia and 20 feet depth is required to
recharge the runoff from the paved area
3. Each recharge well can hold around 4,000 liters of water
Supported by Implemented by
ITC MISSION SUNEHRA KAL
Dos anddont’sforrooftopharvesting
1. Keep the terrace clean. Ensure no organic, chemical, toxic or rusting
material is kept there and do not clean terrace with soap water.
2. Do not paint the terrace with lead or antimony-based paints.
3. In case you have a terrace garden, isolate it from the catchment.
4. Never connect balcony wash pipe to rainwater pipe.
Balcony wash water and clothes wash areas on the rooftop
should have separate piping that leads to the sanitary chamber.
D0s anddont’sforrechargewell
`
1. The recharge wells can be located in or close to storm water drain
and borewells.
2. While locating the recharge wells, sufficient distance should be main-
tained from the sewage chambers, transformer yard, electrical and
cable lines.
3. It is better to locate the recharge wells away from driveways, where
there is no heavy vehicle movement. Concrete rings and concrete cover
slabs need to be reinforced, to take care of smaller vehicle movement.
4. Ideally, between 2 recharge well edges, there should be a distance of
1.5 times the depth of the well. (E.g. for a 20 feet deep well, gap of 30
feet should be maintained)
5. In-drain filters and check dam can be constructed before the water
enters the recharge well. Else the recharge well can get silted up quickly.
MaintenanceofRechargeWell
Recharge wells need to be desilted once in 3- 5 years.
Howmuchdoesrooftopharvesting cost
Well of 3 feet dia and 20 feet dia
can cost around Rs. 35,000/- to Rs.
50,000/- (as of march 2021)
The cost increase as the diameter
and the depth of the well increases.
1. Know your water source like Wells, Borewells, lakes and Rivers.
2. Keep tracking water quality.
3. Don’t use more water than you need.
4. Adopt Rainwater harvesting for Rooftop and Surface runoff.
5. Ensure proper treatment of wastewater, reuse where possible
and ensure responsible discharge of the same.
6. Share your data with the city and remember that the plumber,
well digger and the mason are your partners.
For more information please visit
the site www.bengaluru.urbanwaters.in
5. The sump cover should be sealed to ensure no Sunlight
enters the sump, which could lead to algae formation.
6. The Gate valve needs to be opened and the water
accumulated in the First rain separator needs to be let out.
7. In case you use the stored rainwater for drinking, monitor the
water quality by getting it tested in a local lab once a year.
The average cost for each home in an apartment works out to be in the
range of Rs 2,000/- to Rs 6,000/-