This presentation contains definition, uses, purpose, methodologies, advantages, NBC for rain water harvesting, calculations, components , types of filters used for RWH, and videos.

1. RAIN WATER HARVESTING
Presented By -
Id. Hetvi Trada
M.I.D, SMAID
SMAID
Charutar Vidhya Mandal University
SHANTABEN MANUBHAI PATEL
SCHOOL OF STUDIES & RESEARCH IN
ARCHITECTURE AND INTERIOR DESIGN

2. OUTLINE
― DEFINITION
― USES
― HYDROLOGICAL CYCLE
― WHY TO HARVEST RAIN WATER
― PURPOSE OF HARVESTING RAINWATER
― METHODOLOGIES
― ADVANTAGES OF RAINWATER HARVESTING
― STRUCTURE REQIUREMENT FOR RWH
― CARE TO BE TAKEN IN RWH
― NBC FOR RWH
― CALCULATION
― COMPONENTS OF RWH
― TYPES OF FILTERS USED IN RWH
― VIDEOS
― REFERENCES

3. DEFINITION
― Rainwater harvesting system, also called rainwater collection system or rainwater catchment system, is a
technology that collects and stores rainwater for human use. Rainwater harvesting systems range from
simple rain barrels to more elaborate structures with pumps, tanks, and purification systems.
― Rainwater harvesting can be tracked to the Neolithic age, where the construction and use of waterproof
receptacles to store rainwater were built on the floors of the houses and village location near the
Mediterranean sea in the west, Arabian desert in the south and Mesopotamia in the east.
― There are basically three areas where rainwater can be
used: 1. Irrigation use Indoor, 2. Non-potable use 3.
Whole house, potable use
― Here are some ideas for specific uses of rainwater:
― Hand watering for lawn and garden
― Connect rainwater collection system to
irrigation/sprinkler system
― Washing the vehicles
― Washing the pets
― Refill fountains fish ponds
― Refill swimming pool
― Replace the use of tap water with rainwater to wash
your driveways and sidewalks
― Use it for all potable needs when properly filtered and
disinfected
― Use it for industrial processes instead of municipally
treated water.

4. ― In simplest terms, water makes up about 71% of
the Earth's surface, while the other 29% consists
of continents and islands. To break the numbers
down, 96.5% of all the Earth's water is contained
within the oceans as salt water, while the
remaining 3.5% is freshwater lakes and frozen
water locked up in glaciers and the polar ice caps.
Of that fresh water, almost all of it takes the form
of ice: 69% of it, to be exact.
― The never-ending exchange of water from the
atmosphere to the oceans and back is known as
the hydrologic cycle.
― This cycle is the source of all forms of precipitation (hail, rain, sleet, and snow), and thus of all the water.
― Precipitation stored in streams, lakes and soil evaporates while water stored in plants transpires to form clouds
which store the water in the atmosphere. Currently, about 75% to 80% of conventional water supply is from lakes,
rivers and wells.
― Making the most efficient use of these limited and precious resources is essential. Otherwise, scarcity of water will
be faced by our future generations.
― This includes using appliances and plumbing fixtures that conserve water, not wasting water, and taking
advantage of alternative water sources such as greywater reuse and rain water harvesting.
UNDERSTANDIG THE HYDROLOGICAL CYCLE

5. ― Rainwater Harvesting -yield copious amounts of water. For average rainfall of 1,000mm, approximately four
million liters of rainwater can be collected in a year in an acre of land (4,047 sq.mt).
― As RWH is neither energy-intensive nor labor-intensive, - a cost-effective alternative to other water-accruing
methods, such as desalination of seawater & water transfer.
― With the water table falling rapidly, & with concrete buildings, paved car parks, business complexes, & landfill
dumps taking the place of water bodies, RWH is the most reliable solution for augmenting groundwater level to
attain self-sufficiency in public distribution of water.
WHY TO HARVEST RAIN WATER
PURPOSE OF HARVESTING RAIN WATER
― Rainwater Harvesting techniques can serve the following purposes: Two Major Purposes: Agricultural and human
consumption .
― Freshwater augmentation technology .
― Increase groundwater recharge .
― Reduce storm water discharges, urban floods and overloading of sewage treatment plants.
― Reduce seawater ingress in coastal areas .

6. ― Water harvesting -undertaken through a variety of ways Capturing runoff from rooftops – Roof water harvest .
― Capturing runoff from local catchments – Land harvest .
― Capturing seasonal floodwaters from local streams and Conserving water through watershed management .
― For urban and industrial environment Roof & Land based RWH – Public, Private, Office & Industrial buildings
Pavements, Lawns, Gardens & other open spaces .
RAIN WATER HARVESTING - METHODOLGIES
― Provides self-sufficiency to water supply. Reduces the cost for pumping of groundwater & Provides high quality
water.
― Improves the quality of ground water through dilution when recharged to groundwater .
― Reduces soil erosion in urban areas & is less expensive.
― In hilly terrains, rain water harvesting is preferred . In saline or coastal areas, rain water provides good quality
water and when recharged to groundwater, it reduces salinity and also helps in maintaining balance between the
fresh-saline water interface .
― In Islands, due to limited extent of fresh water aquifers, rain water harvesting is the most preferred source of water
for domestic use . In desert, where rain fall is low, rain water harvesting has been providing relief to people.
ADVANTAGES OF RAIN WATER HARVESTING

7. ― Topography – Availability of land – Rainfall – Economic status
― Built-up areas – Temple tanks – Rooftop harvesting – Wells and radiator wells – Parking lot storage – Recreational
Park ponds.
― Open areas – Percolation ponds – Community wells – Farm ponds –Anicuts across the streams.
TYPE OF STRUCTURE REQIURED FOR RAIN WATER HARVESTING
― Storing rain water for direct use (Most Commonly Used)
― Recharging ground water aquifers, from roof top run off
― Recharging ground water aquifers with runoff from ground area.
METHODS OF STORING RAIN WATER HARVESTING
STORING RAIN WATER FOR DIRECT USE
― In place where the rains occur throughout the year, rain water can be
stored in tanks. However, at places where rains are for 2 to 3 months,
huge volume of storage tanks would have to be provided.
― In such places, it will be more appropriate to use rain water to recharge
ground water aquifers rather than to go for storage.
― If the strata is impermeable, then storing rain water in storage tanks for
direct use is a better method. Similarly, if the ground water is saline/unfit
for human consumption or ground water table is very deep, this method
of rain water harvesting is preferable.

8. ― Rain water that is collected on the roof top of the building may be diverted by drain pipes to a filtration tank (for
bore well, through settlement tank) from which it flows into the recharge well.
― The recharge well should preferably be shallower than the water table. This method of rain water harvesting is
preferable in the areas where the rainfall occurs only for a short period in a year and water table is at a shallow
depth.
RECHARGING GROUND WATER AQUIFERS, FROM ROOF TOP RUN OFF .

9. DIFFERENT WAYS TO HARVEST /RECHARGE THE RAINWATER

11. RECHARGING GROUND WATER AQUIFERS WITH RUNOFF FROM GROUND AREA.
― The rain water that is collected from the open areas may be
diverted by drain pipes to a recharge dug well / bore well
through filter tanks .
― The abandoned bore well/dug well can be used cost
effectively for this purpose.
SIPHONIC DRAINAGE SYSTEM
― It is an installation generally used for special situations such as roof with large spans for structures like hangars,
Airport terminals, stadium and industrial sheds, where the no.of downpipes has to be limited.
― These are designed for full flow of pipes and the roof outlets are
different from conventional ones.
― These system is engineered on the concept of a full bore (a fill
rate of 100%).
― These implies that rainwater flows at high speed through small
diameter pipe work.
― This siphonic effect is created by the kinetic energy derived from
the hydraulic head, caused by the difference in height between
the roof outlet and the discharge point in a building.

12. ― Specialist roof outlets prevent air being sucked in the system.
― The engineering principle of siphonic roof drainage design is based
on Bernoulli's energy equation for steady flow of an incompressible
fluid with constant density where equal energy is created under
positive and negative pressure.
― In order to balance the equation and to guarantee the required
siphoinic effect according to the rainfall intensity, the ideal pipe
dimension per flow path need to be determined.
― In case of syphon system, the outlets of drainage system prevent
vortex formation, there by preventing the air from entering the
pipeline ensuring the entire system is running at full flow.
CREATION OF ARTIFICIAL
RESERVOIRS/LAKES FOR UTILIZATION
OF AVAILABLE STORM WATER
― This shall be based on estimation of
amount of runoff volume based on rainfall
data (for a period of 10 years) considering
the percolation and evaporation losses and
efforts to be made to collect all available
runoff for proper utilization.

13. EXAMPLES OF MICRO-CATCHMENT
BUNDS
NEGARIM SYSTEM
CONTOUR BENCH TERRACE

14. EXAMPLES OF MACRO-CATCHMENT
CONTOUR DITCH
CONTOUR RIDGE
EXAMPLE OF FLOOD WATER DIVERSION

15. CARE TO BE TAKEN IN RAINWATER HARVESTING
― No sewage or waste water should be admitted in to the system.
― No waste water from areas likely to have oil, grease or other pollutants should be connected to the system.
― Each structure/well shall have an inlet chamber with a silt trap to prevent any silt from finding its way in to the
subsoil water.
― The wells should be terminated at least 5m above the natural static soil at its highest level so that the
incoming flow passes through the natural ground condition and prevent contamination hazards.
NATIONAL BUILDING CODE
― The rain water collected on the roof
top is transported down to storage
facility through down spouts /
conduits.
― Conduits can be of any material like
PVC, GI or cast iron.
― The conduits should be free of lead
and any other treatment which could
contaminate the water.

16. TYPE OF CATCHMENT RUNOFF COEFFICIENT C
FOREST 0.1-0.3
MEADOW 0.1-0.4
CULTIVATED FIELD 0.2-0.4
BARE EARTH 0.2-0.9
PAVEMENT,CONCRETE OR ASPHALT 0.8-0.9
FLAT RESIDENTIAL ,ABOUT 30% IMPERVIOUS 0.4
FLAT RESIDENTIAL ,ABOUT 60% IMPERVIOUS 0.55
SLOPING RESIDENTIAL ,ABOUT 50% IMPERVIOUS 0.65
SLOPING BUILTUP ,ABOUT 70% IMPERVIOUS 0.8
FLAT COMMERCIAL,ABOUT 90% IMPERVIOUS 0.8
TILES 0.8-0.9
CORRUGATED SHEETS 0.7-0.9
SOIL ON SLOPES THAN 10% 0.0-0.3
ROCKY NATURAL CATCHMENTS 0.2-0.5
RUN OFF CO-EFFICIENTS FOR VARIOUS SURFACES (NBC)
FORMULA TO CALCULATE RAIN WATER RUNOFF
Total discharge ,Q= CIA
WHERE,
Q= Quantity Runoff
C= Run-off Co-efficient
I = Intensity Of Rainfall
A= Catchment Area

17. NUMBER COMPONENT DESCRIPTION MAINTENANCE ACTIONS
SUGGESTED
FREQUENCY
1 Collection system
Roof surface and gutters to
capture rainwater and send
it to the storage system.
Keep clean and clear of excessive
debris, especially after prolonged
dry periods or after storms.
Inspect roof surface and ensure
water flows and drains properly as
intended.
Weekly
2 Inlet filter
Screen filter to catch large
debris.
Clean out filter and replace at
regular manufacturer-specified
intervals.
Weekly;
manufacturer-
specified intervals
3 First flush diverter
Diverter that removes debris
not captured by the inlet
filter from the initial stream
of rainwater.
Keep clean and clear of excessive
debris, especially after prolonged
dry periods or after storms.
Ensure the diverter is functioning as
intended, diverting only the initial
flush of water during rainfall.
Monthly and after
prolonged storms
COMPONENETS OF RAIN WATER HARVESTING

18. 4 Storage tank
Storage tanks composed of
FDA-approved, food-grade
polyester resin material that
is green in color, which
helps to reduce bacterial
growth.
Inspect tank for cracks or leakage.
Infrequent blowdown may be
needed to remove sediment from
the bottom of the tank. If filters are
regularly maintained, sediment
accrual should be minimal (2 mm to
2 in. per year).
Annually
5 Overflow
Drainage spout that allows
for overflow if the storage
tank gets full.
Visually inspect overflow spout to
ensure it is clear of debris.
Monthly
6 Controls
Control system that
monitors water level and
filtration system.
Request manufacturer maintenance
as needed to repair any controls
issues.
Check that wiring is in good
condition.
Monthly
7 Treatment system
Filtration and disinfection
system that treats the water
to non-potable or potable
standards.
Clean and replace filters at
manufacturer-specified intervals.
Ensure treatment system dosing
intervals are sufficient to meet water
quality requirements in the system.
Manufacturer-
specified intervals
8 Pump
Pumps move water through
the system and to the end
use.
Check motor condition. Investigate
excessive vibration, noise, or
temperature.
Perform pump maintenance, such as
bearing lubrication, in accordance
with manufacturer specifications.
Monthly;
Manufacturer-
specified intervals

19. 9 Backflow prevention
Backflow preventer to
ensure that water cannot
flow under instances of
negative pressure.
Have an approved professional test
annually or at a frequency required
by local regulation.
Annually
10 Flow meter
Flow meter (with data
logger) to measure water
production.
Ensure meter is calibrated per meter
manufacturer instructions.
Track water use regularly through
meter readings automatically (with
data logger) or manually with a log
book.
Monthly
11 Power supply
Systems may use
conventional power sources,
or, to improve off-grid
capabilities, may use
alternative sources such as
stand-alone or grid-tied
solar systems.
Check power supply and equipment
after power outages and ensure no
damage to components.
Follow manufacturer operation and
maintenance guidelines for
alternative stand-alone power
supplies (e.g., solar photovoltaic
panels).
As needed;
Manufacturer-
specified intervals
12 Water level indicator
Monitors the water level in
the storage tank.
Ensure the indicator is functioning
as intended.
Monthly
13
Potable water
connection
Make-up water supply (e.g.,
municipal water) to meet
system needs when rainfall
is not adequate to meet
demand (not pictured).
Inspect potable water supply
connection and backflow preventer
and ensure that connections are in
good condition without leaks.
Comply with any regulations for
testing required by local ordinances.
Annually

20. FILTERS
― If the collected water from roof top is to be used for human consumption directly, a filter unit is required to be
installed in RWH system before storage tank. The filter is used to remove suspended pollutants from rain water
collected over roof. The filter unit is basically a chamber filled with filtering media such as fiber, coarse sand and
gravel layers to remove debris and dirt from water before it enters the storage tank.
― There are various type of filters which have been developed all over the country. The type and selection of
filters is governed by the final use of harvested rain water and economy.
1. SAND FILTER
― In the sand filters, the main filtering media is
commonly available sand sandwitched between two
layers of gravels.
― The filter can be constructed in a galvanized iron or
ferro cement tank. This is a simple type of filter which is
easy to construct and maintain.
― The sand fillers are very effective in removing turbidity,
color and microorganism.
― This is almost similar to sand filter except that a 10-15 cm thick charcoal layer placed above the sand layer.
Charcoal layer inside the filter result into better filtration and purification. The commonly used charcoal water
filter is shown in Figure.
2. CHARCOAL FILTER

21. ― Most residents in Dewas, Madhya Pradesh, have wells in their houses. Formerly, all that those wells would do was
extract groundwater. But then, the district administration of Dewas initiated a groundwater recharge scheme.
― Because of regular extraction of ground water, the water table is going down rapidly. To recharge the ground
water, all the water collected from the roof top is passed through a filter system called Dewas filter. The filtered
water is finally put into service tube well for recharging the well.
― The filter consists of a PVC pipe 140mm in diameter and 1.2m long. There are three chambers. The first
purification chamber has pebbles of size varying between 2-6 mm, the second chamber has slightly larger
pebbles between 6 to 12 mm and the third chamber has largest 12 – 20mm pebbles.
― There is a mesh on the out flow side, through which clean water flows out after passing through the three
chambers. This is one of the most popular filter type being used in RWH systems.
2. CHARCOAL FILTER 3. PVC FILTERS (DEWAS FILTER)

22. 4. SPONGE FILTERS (VARUN FILTER)
― This filter has been developed by Shri S.Viswanath, a
Bangalore based water harvesting expert.
― “Varun” is made from 90 lit. High Density Poly Ethylene (HDPE)
drum. The lid is turned over and holes are punched in it.
― The punched lid acts as a sieve which keeps out large leaves,
twigs etc.
― Rain water coming out of the lid sieve then passes through
three layers of sponge and 120mm thick layer of coarse sand.
― Because of sponge layers, the cleaning of filter becomes very
easy. The first layer of sponge can be removed and cleaned
very easily in a bucket of water.
― Because of the layers of sponge, the sand layer does not get
contaminated and does not require any back washing /
cleaning.
― After sand layer, the layer of 230mm aggregates is applied and
at the end mesh is fitted at the outlet.
― This filter can handle about 50mm per hour intensity rain fall
from a 50 sq.mt roof area.
90 LITRES HDPE
DRUM
NETLON MESH AT
BYE PASS OUTLET
BYE PASS
OUTLET
SPONGE 12MM
THK/NETLON MESH
90 MM COARSE SAND
230 MM AGGREGATES
NETLON MESH OUTLET
TO SUMP OPEN WELL
FIRST RAIN SEPARATOR
BYE-PASS
THREADED END CAP
TAP
DOWN PIPE FROM
ROOF TOP

23. 5. HORIZONTAL ROUGHNENING FILTER / SLOW SAND FILTER
― The slow sand filter (SSF) consists of fine sand in a
channel of size one sq.mt in cross section and eight
metre in length, laid across the tank embankment.
― The filter channel consists of three uniform compartments,
the first packed with broken bricks, the second with coarse
sand, followed by fine sand in the third compartment.
― The HRF usually consists of filter material like gravel and
coarse sand that successively decreases in size from 25
mm to 4 mm.
― The bulk of solids in the incoming water is separated by this coarse filter media or HRF. At every outlet and
inlet point of the channel, fine graded mesh is implanted to prevent entry of finer materials into the sump. The
water after passing through SSF is stored in a sump. From this sump water can be supplied through pipe line
or can be extracted through hand pump.
6. RAINWATER PURIFICATION CENTRE
― Thisfilterhasbeendevelopedby threeNetherlandsbased companies for conversion of rain water to drinking
water and is popularly known as Rain PC.
― Rain PC is made of ultra violet resistant poly-ethylene housing and cover, stainless steel rods and bolts, a
nickel-brass valve and an adapter for maintaining constant volume.

24. ― This filtercaneffectivelyremove E-coli andother bacteria from water using Xenotex-A and active carbon
cartridges along with ultra membrane filtration modules.
― This filter is easy to operate and maintain andneeds no power. This operates at low gravity pressure and
maintains nearly constant volume irrespectiveof water pressure.
― The system is capableof providing a constant flow of about 40 lit. ofrain water per hour. The Xenotex- A and
activated carbon cartridges processes up to 20,000 liters of water and can be regenerated up to 10 times.

25. RAINWATER HARVESTING VIDEO (BY AMBUJA EXPERTS)

26. SIPHONIC RAINWATER HARVESTING VIDEO

27. ― https://archi-monarch.com/rainwater-harvesting/
― https://byjus.com/biology/rainwater-harvesting/#how-to-harvest-the-rainwater?
― https://twitter.com/zenrainman/status/1166906780846366720/photo/1
― https://cleanawater.com.au/information-centre/guide-to-rainwater-harvesting-and-treatment
― https://www.energy.gov/eere/femp/water-efficient-technology-opportunity-rainwater-harvesting-systems
― https://www.engineeringcivil.com/groundwater-recharge-by-waste-water.html
― http://www.rainwaterharvesting.org/urban/components.htm
― 428738647-Rain-Water-Harvesting-PPT-3.pdf
― docdownloader.com-pdf-rain-water-harvesting-2-dd_25c7e6b5538a1389f0738d50d8fa7cda.pdf
― RWH NPTEL.pdf
REFERENCES

28. THANK YOU