This is a brief presentation about rain water harvesting, how rainwater can be used in our day to day life style and how harvesting rain water can be integrated directly into the architecture of the building.

1. RAJAY BAJRACHARYA
075BAR038
PULCHOWK CAMPUS

2.  What is Rainwater harvesting?
 Purpose and Use
 Significance in the present context of urbanization
 Methods of water harvesting in a settlement and in an individual building
unit.
CONTENTS

3. Introduction
 Rain is a part of hydrologic cycle, which transports water from the ocean to land
and back again. Solar radiation warms the ocean and drives evaporation. The
97% of earths water that was previously unusable for life form is now usable.
Only 0.001% of earth’s water is ever found in the atmosphere at one time but
the atmosphere none the less serves as the conduit that transports water from
the ocean to the mainland.

4. • Rainwater harvesting is a technology used for collecting and storing
rainwater from rooftops, the land surface or rock catchments using
simple techniques such as jars and pots as well as more complex
techniques such as underground check dams.
• Reduce our dependence on dams, watersupply tanks and other systems
used for water storage and supply.
• Reduction of water bills.
• Community’s drinking water supply is conserved as recycled rainwater is
used for toilets gardens and other washing purposes.
• Helps in creating new wetlands and replenishing the ones that currently
exist.

5. SURFACE RUNOFF HARVESTING
 In urban area rainwater flows
away as surface runoff. This runoff
could be caught and used for
recharging aquifers by adopting
appropriate methods.
ROOF TOP RAINWATER HARVESTING.
 It is a system of catching rainwater
where it falls. In rooftop
harvesting, the roof becomes the
catchments, and the rainwater is
collected from the roof of the
house/building. This method is
less expensive and very effective.

6. • Rainwater falling in roofs, paved surface
and other open areas should be collected
and disposed immediately and quickly. An
independent system should be created
for storm water disposal.
• The rain water from balconies, and terrace
should be drained in a efficient manner.

7.  The pitch of the roof should be designed according to the frequency and
intensity of rainfall
1. For a single storey roof, slope can be defined in any direction allowing
the rain water to drain naturally
2. For larger buildings, free fall of rain water from roof is not advisable. It
shoud be drained through roof gutters and pipes to a suitable location.

8. The surface that receives rainfall directly is the catchment
of rainwater harvesting system. It may be terrace,
courtyard, or paved or unpaved open ground.
• Rainwater from rooftop should be carried through down
take water pipes or drains to storage/harvesting system.
Water pipes should be UV resistant (ISI HDPE/PVC pipes)
of required capacity.

9. • First flush: First flush is a device used to flush off the water
received in first shower. The first shower of rains needs to be
flushed-off to avoid contaminating storable/rechargeable
by the probable contaminants of the atmosphere and the
catchment roof.
• Storage system: All collected rain water are store in tank or
barrels used.
• Delivery system: It is a system to delivered of water for uses.
There are use of pumps to take out water from tank and
for many purpose . Water is deliver by pipes.
• Filtration system: Filters are used for treatment of water to
effectively remove turbidity, color and microorganisms. After
first flushing of rainfall, water should pass through filters. There
are different types of filters in practice, but basic function is to
purify water.
Sand gravel filter
Charcoal filter
PVC pipe filter

11. • Surface water runoff : Water from streets are carried from drains into
reservoirs and treated for use
• Rooftop harvesting : Rainwater is collected from rooftops of homes, offices
and other buildings
• Recharge pits : Pits are made and filled with sand, coarse gravel, rocks
which act as natural filters
• Old abandoned wells

13. Local people can easily be trained to build RWH systems themselves. This
reduces costs and encourages more participation, ownership and
sustainability at community level (HATUM & WORM 2006)
Rainwater is better than other available or traditional sources (groundwater
may be unusable due to fluoride, salinity or arsenic) (HATUM & WORM
2006)
Costs for buying water and time to extract from the city water supply can
be saved (SHRESTHA 2010)
It provides water at the point of consumption (HATUM & WORM 2006)
Not affected by local geology or topography (HATUM & WORM 2006)
Almost all roofing material is acceptable for collecting water for household
purposes (HATUM & WORM 2006)
Rooftop RWH reduces the amount of rainwater going into sewers, drains
and may reduce flooding and clogging of water channels and uptakes
(WATERAID 2008)

17. https://architizer.com/blog/inspiration/collections/rainwater-collection/
http://dudbc.gov.np/uploads/default/files/5516d1570820fec0d862760faeac47a9.pdf
https://www.britannica.com/technology/rainwater-harvesting-
system#:~:text=Rainwater%20harvesting%20system%2C%20also%20called,%2C%20tanks%2C%20and%20purifica
tion%20systems.
https://www.waterboards.ca.gov/water_issues/programs/swamp/docs/cwt/guidance/513.pdf
https://www.pinterest.com/pin/430023464402495798/
https://sswm.info/sswm-solutions-bop-markets/affordable-wash-services-and-products/affordable-water-
supply/rainwater-harvesting-%28urban%29