Technical design-of-rwh (2)

1. ShivaliShivali JainerJainer
Center for Science & Environment, New DelhiCenter for Science & Environment, New Delhi
TrainingTraining programmeprogramme on functional areaon functional area--water pollutionwater pollution
monitoring, prevention and control (WP)monitoring, prevention and control (WP)
February, 2016February, 2016
ShivaliShivali JainerJainer
Center for Science & Environment, New DelhiCenter for Science & Environment, New Delhi

2. Topics covered
 RWH System: Component and analysis
 RWH design : Storage / Recharge
 Construction & Costing
 Case studies on RWH for Industrial landuse
 RWH System: Component and analysis
 RWH design : Storage / Recharge
 Construction & Costing
 Case studies on RWH for Industrial landuse

3. References
RAINWATER: Availability in area,
management to meet water demand
in local areas.
STORM WATER: managed through
surface water bodies+ optimal
storm water channel : Green
infrastructure
WASTE WATER: managed and
reused for non‐domestic purposes
Sheet No. 2
Urban Development:
planned and executed in a manner so as to
lower the hydrological impact of urbanization
and present opportunities for improved water
management
STORM WATER: managed through
surface water bodies+ optimal
storm water channel : Green
infrastructure
Storm water and resource managementStorm water and resource management

6. Why RWH is
adopted?
Mandatory
Govt. Rule
Voluntary
Environmental
friendly
Real NecessityReal Necessity
Insufficient water
quantity & quality
(e.g. Arsenic issue)
Insufficient water
quantity & quality
(e.g. Arsenic issue)
During
Disaster
Research/
Knowledge
(e.g. Institutes)
Water sensitive design
for industrial landuse:
-Opportunities:
More open space
available, low end use
activities
-Threats: Chemicals,
water loving solvents
Govt. Rule
CSR Activity
Adaptation
(climate change
impact)
Environmental
friendly
Social status
(Green fashion?)
Insufficient water
quantity & quality
(e.g. Arsenic issue)
Insufficient water
quantity & quality
(e.g. Arsenic issue)
Longer dry spellsLonger dry spells
Water table
depletion
Water table
depletion
Water sensitive design
for industrial landuse:
-Opportunities:
More open space
available, low end use
activities
-Threats: Chemicals,
water loving solvents

7. Benefits of RWH
 Rainwater is purest form of water since it is condensed
 It is devoid of pollutants
 It is freely available
 RWH is not complex and costly
 It can be easily adopted and managed without much skills
 It reduces dependency on external and costly resources
 Considering increasing demand of water, poor services
offered by ULBs due to various reasons, future possible
climatic changes etc. RWH will be wise solution
 Rainwater is purest form of water since it is condensed
 It is devoid of pollutants
 It is freely available
 RWH is not complex and costly
 It can be easily adopted and managed without much skills
 It reduces dependency on external and costly resources
 Considering increasing demand of water, poor services
offered by ULBs due to various reasons, future possible
climatic changes etc. RWH will be wise solution

8. RWH: Components

9. Rainwater can be
harvested for two
reasons:
RAINWATER
Ready to use with storage above or below ground
Diverted into ground for withdrawal purpose
(Groundwater recharging)
Rainwater can be stored in tanks Rainwater can be recharged into ground

10. Data to be collected for
designing RWH system
INFORMATIONCOLLECTION
Catchment typesCatchment types
Meteorological data
Water demand & purpose of usageWater demand & purpose of usage
Data collection for designing RWH systemData collection for designing RWH system
Data to be collected for
designing RWH system
INFORMATIONCOLLECTION
Hydro-geological informationHydro-geological information
Community support/ Budget
Site Plan

11. CATCHMENTSCATCHMENTS
Roof tops
PavedPaved
CatchmentCatchment
SizeSize
CatchmentCatchment
SizeSize
Catchment DataCatchment Data
TiledTiled
Tin sheetsTin sheets
Cement
ForFor
CATCHMENTSCATCHMENTS
Land
surface
PavedPaved
UnpavedUnpaved
Semi -pavedSemi -paved
RunoffRunoff
coefficientcoefficient
RunoffRunoff
coefficientcoefficient
ForFor

12. Unpaved
Paved
Roof top
Catchment Variety
Catchment Data
Size of Catchment area
Catchment Variety
Sloping / flat / Barrel roof
Area = Length (L) x Breadth (B)

13. Runoff Coefficients and RWH potentialRunoff Coefficients and RWH potential
Water that will be
available for storage
or recharge.
More
Run off
Smooth
surfaces
Catchment Variety Surface Types Runoff
co-efficient More
Run off
Absorb
water and
less Run off.
Smooth
surfaces
Unpaved
surfaces
Catchment Variety Surface Types Runoff
co-efficient
ROOF CATCHMENTS
Tiles 0.8-0.9
Corrugated metal sheets 0.7-0.9
Concrete 0.70-0.95
GROUND SURFACE
COVERED with
Soil (slope <10%) 0.0-0.3
Rocky material catchment 0.2-0.5
Lawns, sandy soils having
(slope 2%)
0.05-0.10
Lawns, sandy soils having
(slope 2-7% )
0.10-0.15
Brick pavements 0.70-0.85
Park / Cemeteries 0.1- 0.25
Play grounds 0.2-0.35
Asphalt and Concrete
pavement
0.70-0.95
Source:
(CPWD manual on rainwater harvesting and conservation,
2002)

14. Urban Catchments variationsUrban Catchments variations
• Roof Tops
• Paved Area (Roads,
footpaths, Flyovers)
• Unpaved Areas
(lawns, open
grounds)
• Semi paved Areas
Rooftops Roofs + Unpaved
Sloping or flat roof
Type of catchment Possible contaminations
Industrial region
Toxic materials such as chemicals, oil,
grease, heavy metals
Roads, highways,
parking areas
Oil, grease, debris, plastic waste
Agricultural areas,
lawns, gardens
Pesticides, fertilizers, silt
Semi Paved Surface

15. METEOROLOGICAL
DATA
Annual Rainfall (Avg. of 25 yrs)
Rainfall Distribution
Potential of
RWH
DETERMINES
Meteorological DataMeteorological DataMETEOROLOGICAL
DATA
Rainfall Distribution
Peak Rainfall Intensity Option
Selection
DETERMINES

16. Example of rainfall patternsExample of rainfall patterns
2 1 0 3
20
103
247
288
83
23 14 5
0
50
100
150
200
250
300
350
Rainfall(mm)
19 20 15 21 25
70
237 235
113
17
9 9
0
50
100
150
200
250
Rainfall
Bangalore
Ahmedabad
0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
New Delhi

17. Runoff =A x R x C
A=Area
R=Rainfall in metres
C=Runoff coefficient
An example
 A=100 m2
 R = 600 millimeters
 C=0.80
Runoff = 48,000 liters
How much water can we collect?
Runoff =A x R x C
A=Area
R=Rainfall in metres
C=Runoff coefficient
An example
 A=100 m2
 R = 600 millimeters
 C=0.80
Runoff = 48,000 liters

18. WATER
CONSUMPTION
DEMAND:
Quantity of water used
Per capita water demand
RequirementsRequirements
Design
specification
INFLUENCEINFLUENCE
Water Consumption &Water Consumption & DemandDemandWATER
CONSUMPTION
DEMAND:
Per capita water demand
Water demand during the driest period
Design
specification
Design
specification
INFLUENCEINFLUENCE

19. Geologicaland
Hydrologicalinformation Nature of aquifer
Groundwater level
Nature of terrain
•If aquifers are
impermeable, non-
porous
•If depth of water level is
less than 8 meters
•If the terrain is hilly, rocky
or undulating
•If the soil is clayey
•If comprises of massive
rocks
(Basalt, Granite)
Geological and Hydrological information
Geologicaland
Hydrologicalinformation
Nature of soil
Geological formation
Nature of terrain
•If aquifers are
impermeable, non-
porous
•If depth of water level is
less than 8 meters
•If the terrain is hilly, rocky
or undulating
•If the soil is clayey
•If comprises of massive
rocks
(Basalt, Granite)

20. Conveyance or
Conduit System
To collect and transport rainwater to the storage
tank or recharge structures
Gutters
Down take pipes
Horizontal Channels all around the edge of a sloping roof
Vertical conduits that carry rainwater
Material:
•Plain galvanized iron sheet
•Mild Steel Pipes
•Semi-circular gutters of PVC
•Bamboo or betel trunks
Material:
•Plain galvanized iron sheet
•Mild Steel Pipes
•Semi-circular gutters of PVC
•Bamboo or betel trunks

21. Collecting Rainwater: Plumbing Concerns
In flat catchments velocity of flow towards the collecting inlets shall be limited.
To limit velocity of flow, slope of catchment surface shall
be:
1. For rough surface 100 : 1 and
2. For smooth surface 200 : 1.
The inlet size shall at least one size bigger than the collection pipe
size.
Domed Roof Outlet Grating is
designed with a removable
push fit high domed grating to
prevent blockage
http://www.besstem.com/products_details.asp
The inlet size shall at least one size bigger than the collection pipe
size.
4”Dia RDP
(Rainwater
Down Pipe)
6x4
Reducer
Dome
Shaped
Grating

22. Diameter of
RDP mm
(in.)
Maximum Rainfall mm/hr (in/hr)
50(2) 75(3) 100(4) 125(5) 150(6)
75(3) 153 102 76 61 51
100(4) 349 233 175 140 116
125(5) 621 414 310 248 207
Diameter of rainwater down pipe in mm based on roof area (sqm) and intensity of
rain (mm/hr). Slope of horizontal portion of pipe is 100:1.
Sizing Rainwater Collection Pipe
125(5) 621 414 310 248 207
150(6) 994 663 497 398 331
200(8) 2137 1424 1068 855 706
250(10) 3846 2564 1923 1540 1282
300(12) 6187 4125 3094 2476 2062
375(15) 10126 6763 5528 4422 3683

23. Conveyance or Storm water drains
Open channel Channel with screening

24.  Catchments, rain outlets
(in existing buildings)
 Space available for water harvesting
structures
 Plumbing (water and sewage) and
electrical lines at the site
 Contour map to find out about the
natural drainage & slope
 Other features like a compost pit etc.
Studying site plan/details
Siteplan/details
Catchments
Space availability
Plumbing
Contour map
BUDGET AVAILABLE AND TENTATIVE
COST: Cost is main factor for rainwater-
harvesting project. A careful analysis on
storage requirements against the cost has to
be carried out prior to implementation of the
project.
Siteplan/details
Other features
Contour map

25. First flush device Ensures that runoff from the catchment does not
contaminates storage system (tanks, aquifers)
Normally first 2.5 mm of rainfall is
flushed away
Rejects air-borne and other pollutants
from the catchments entering in
RWH systems

26. First flush devices
FIRSTFLUSHDESIGN
DEPENDSON
Catchment ConditionCatchment Condition
Catchment TypesCatchment Types
Delay time before the rainy seasonDelay time before the rainy season
FIRSTFLUSHDESIGN
DEPENDSON
Delay time before the rainy seasonDelay time before the rainy season
Intensity and amount of rainfallIntensity and amount of rainfall
Catchment AreaCatchment Area
Thumb Rule: First 15Thumb Rule: First 15--20 minutes of first rainfall be discarded as first flush20 minutes of first rainfall be discarded as first flush

27. Collection Conveyance Filtration
Selection of filters depends on
Filtration System
StorageStorage RechargeRecharge
Purpose of use Type of recharge
structures
•Quality of run
off: Type of
catchment
•Amount of silt
load

28. Filters
Four types of filtration processes can be used in the RWH system:
Catchment stage: Separation or Screening: Filtration that separates out gross
pollutants
Conveyance stage: First Flush: The first spell of rain containing dissolved
impurities
Conveyance stage: First Flush: The first spell of rain containing dissolved
impurities
Filteration:Settling tanks removes silt and coarse
materials
Storage /Recharge: Filtration: Filters remove dissolved organic and inorganic
particles in the rainwater

29. Recharge: Preferably designed when water table is
declining.
Storage: Preferably designed when rain is temporally
distributed and not intensive, i.e. number of rainy days are
more
Storage/Recharge systems
Rainwater can be diverted into aquifers through suitable structures like dug
wells, bore wells, recharge wells and recharge trench

30. Parameter Type/condition Recommended
structure
(Storage, recharge
or both?)
Nature of aquifer Impermeable, non-porous, non-
homogeneous, hard rock area
Depth of
groundwater table
More than 8 metres
Nature of terrain Hilly, rocky or undulating
Type of structures
Storage
Recharge and
storage
StorageNature of terrain Hilly, rocky or undulating
Uniform or flat, alluvial and sedimentary
Nature of soil Alluvial, sandy, loamy
soils, gravel, silty, with boulders or
small stones (kankar)
Clayey soil
Nature of geological
formation
Massive rocks(such as the Deccan trap)
Fractured, faulted or folded rocks, or
comprises of weathered, jointed or
fissured rocks
Storage
Recharge and
storage
Recharge and
storage
Storage
Storage
Recharge and
storage

31. Parameter Type/condition Recommended
structure
(Storage, recharge or
both?)
Nature of rainfall
and monsoon
Number of rainy days are more,
bimodal monsoon, not intensive,
uniformly distributed
Unimodal monsoon, rainfall
available only for a few months
Type of structures
Storage
Recharge and
storage
Unimodal monsoon, rainfall
available only for a few months
Recharge and
storage

32. GW recharge structures : Urban context
• Recharge well
• Recharge pit
• Recharge trenches
• Dried up/ abandoned tube well converted into a
recharge structures
• Dug/Open well
• Recharge well
• Recharge pit
• Recharge trenches
• Dried up/ abandoned tube well converted into a
recharge structures
• Dug/Open well
• Recharge well
• Recharge pit
• Recharge trenches
• Dried up/ abandoned tube well converted into a
recharge structures
• Dug/Open well
• Recharge well
• Recharge pit
• Recharge trenches
• Dried up/ abandoned tube well converted into a
recharge structures
• Dug/Open well

33. Recharge structure: Design Parameters
For designing the Recharge structure, following parameters need to be considered:
1.) Size of the Catchment
2.) Peak hour intensity of Rainfall
3.) Rate of recharge, which depends on the geological nature of the site
For designing the Recharge structure, following parameters need to be considered:
1.) Size of the Catchment
2.) Peak hour intensity of Rainfall
3.) Rate of recharge, which depends on the geological nature of the site
Peak rainfall intensity in 15 minutes= 25 mm
 For a rooftop area of 100 sq m holding capacity of the recharge well =
Catchment area X peak rainfall intensity for 15 minutes x run0ff coefficient =
 Assuming a void ratioa void ratio of 0.5, the required capacity of a recharge tank
= (100 x 0.025 x 0.85) / 0.5(100 x 0.025 x 0.85) / 0.5
 4.25 cum. (Total) which can be divided into different structures of
trenches, Recharge well and Recharge Pits.
Peak rainfall intensity in 15 minutes= 25 mm
 For a rooftop area of 100 sq m holding capacity of the recharge well =
Catchment area X peak rainfall intensity for 15 minutes x run0ff coefficient =
 Assuming a void ratioa void ratio of 0.5, the required capacity of a recharge tank
= (100 x 0.025 x 0.85) / 0.5(100 x 0.025 x 0.85) / 0.5
 4.25 cum. (Total) which can be divided into different structures of
trenches, Recharge well and Recharge Pits.
Peak rainfall intensity in 15 minutes= 25 mm
 For a rooftop area of 100 sq m holding capacity of the recharge well =
Catchment area X peak rainfall intensity for 15 minutes x run0ff coefficient =
 Assuming a void ratioa void ratio of 0.5, the required capacity of a recharge tank
= (100 x 0.025 x 0.85) / 0.5(100 x 0.025 x 0.85) / 0.5
 4.25 cum. (Total) which can be divided into different structures of
trenches, Recharge well and Recharge Pits.
Peak rainfall intensity in 15 minutes= 25 mm
 For a rooftop area of 100 sq m holding capacity of the recharge well =
Catchment area X peak rainfall intensity for 15 minutes x run0ff coefficient =
 Assuming a void ratioa void ratio of 0.5, the required capacity of a recharge tank
= (100 x 0.025 x 0.85) / 0.5(100 x 0.025 x 0.85) / 0.5
 4.25 cum. (Total) which can be divided into different structures of
trenches, Recharge well and Recharge Pits.
•Rainfall intensity: 90 mm
•Catchment area= 100 sq m
•Rainfall intensity: 90 mm
•Catchment area= 100 sq m
Runoff =A x R x C

34. The maps are
published by
Meteorological
agencies and can
help to determine
peak hour intensity
The maps are
published by
Meteorological
agencies and can
help to determine
peak hour intensity
The maps are
published by
Meteorological
agencies and can
help to determine
peak hour intensity
The maps are
published by
Meteorological
agencies and can
help to determine
peak hour intensity

35. Recharge Well – Cross section

36. Recharge Well

37. Recharge well

43. Abandoned tube well
Specifications:
oA pit of desired size is
constructed around the
existing casing pipe of dry
tube well.
oThe pit can also be away
from it if there is no space.
oFilled with filtering
material
Specifications:
oA pit of desired size is
constructed around the
existing casing pipe of dry
tube well.
oThe pit can also be away
from it if there is no space.
oFilled with filtering
material
•Dry or abandoned bores available
•Quality of water is ensured to be free of contaminants as abandoned tube
wells may put water directly into aquifer and there may not be any chances
of natural filtration.
•Specially suitable for rooftop rainwater

44. Step 1: Understand catchments & site conditions
Step 2: Identify rain outlets and slopeStep 3: Location of existing or new collection chambersStep 4: Interconnect different outlets
Step 5: Divert rainwater into recharge structures - interconnect different
outlets

45. Defunct bore well
Recharge pits with bores
RWH-Centre for Science and Environment (CSE), New Delhi
Recharge pits with bores
Recharge well
Municipal storm water drain
Desilting pond
Recharge trench

46. Storage system – Materials
PVC Tanks
Ferro-Cement Tanks
Earthen Tanks
Brick Masonry Tanks
Tanks should be made of durable and
waterproof materials. The inside of the
tank must have a non-toxic surface
particularly if the water will be used for
drinking purposes
PVC Tanks
Earthen Tanks
Under ground

47. Methods to determine size of tanks
Based on minimum requirements
Storage = No. of water users X No. of dry days X Per capita demand
Based on availability
Tank capacity according to volume to rainwater to be collected from catchment
Based on demand
Tank capacity according to volume to water demand for scarcity/dry days
Based on water balance method
Tank capacity Arrive d from maximum water quantity collected any one time

48. Based on minimum requirements
Size of storage tank V = n x d x q
Where n : no. of water users
d : no. of dry days / scarcity period
q : per capita demand
Storage = No. of water users X No. of dry days X Per capita demand
Number of people in a family =6
Per capita consumption of water per day= 10 liters
Total demand for dry period =6x10x100= 6,000 liters
Free board= add 10 per cent volume =6,600 liters.
A storage of 6,600 liters (6.6 cum )can be built

49. Based on availability of rainfall
Sizing the tank based on availability
•Where rainfall is for only short period and not likely to meet all your demand
•If available water is less than the demand
•Tank capacity according to volume to rainwater to be collected from catchment
 Roof top area: 100 sqm
 Per capita consumption of water per day= 60 liters
 Water requirement for dry days= 5x60x100
=30,000 liters
 Available rainwater =100x250x.8
=20,000 liters
Demand> Availability, Sizing of tank based on availability :20,000 liters
 Roof top area: 100 sqm
 Per capita consumption of water per day= 60 liters
 Water requirement for dry days= 5x60x100
=30,000 liters
 Available rainwater =100x250x.8
=20,000 liters
Demand> Availability, Sizing of tank based on availability :20,000 liters
•Rainfall: 250 mm
•Number of persons=5
•Number of dry days=100

50. Based on water demand
 Roof top area : 100 sqm
 Per capita consumption of water per day= 100 liters
 Water for dry days= 4x100x100
=40,000 liters
 Available rainwater =100x1100x.8
=88,000 liters
Availability > Demand, Sizing of tank based on demand:40,000
liters
•If rainfall is more than the water need
•Tank capacity according to volume of water demand for scarcity/dry days
 Roof top area : 100 sqm
 Per capita consumption of water per day= 100 liters
 Water for dry days= 4x100x100
=40,000 liters
 Available rainwater =100x1100x.8
=88,000 liters
Availability > Demand, Sizing of tank based on demand:40,000
liters
•Rainfall: 1.100 mm
•Number of persons=4
•Number of dry days=100

51. Total Water Demand for 5 members in one month for drinking and
cooking for a month (30Liters/day) = 30x30 =900 Liters
Roof top area: 60 sqm; Runoff coeffient: 0 .85
Minimum rainfall months = December and January
Storage required= 900+ 900 + 900 = 2700 liters
Final Tank Size = 3 cum
Sizing the tank based Water Balance Method
• Get monthly/weekly data rainfall
• Prepare table showing pattern of inflow and outflow
• Arrive at maximum water quantity in tank at any one time
• This is the recommended tank size
How to determine the Size of the tank?
Regular
months =
900
T
o
t
a
l
=
2
7
0
0
Total Water Demand for 5 members in one month for drinking and
cooking for a month (30Liters/day) = 30x30 =900 Liters
Roof top area: 60 sqm; Runoff coeffient: 0 .85
Minimum rainfall months = December and January
Storage required= 900+ 900 + 900 = 2700 liters
Final Tank Size = 3 cum
Dec = 900
Regular
months =
900
T
o
t
a
l
=
2
7
0
0
Jan = 900

52. Water Balance Method
• Volume accumulated in the tank based on monthly rainfall
• Prepare table showing pattern of inflow and outflow
• Arrive at maximum water quantity in tank at any one time
• This is the recommended tank size

53. When constructing a storage tank
2. Inlet
1. Cover
3. Overflow
 Tanks should be properly covered to
prevent algal growth.
Inlet pipe should come from a level
that is higher than the tank top.
There must be overflow pipe –
Covered with mesh
The outlet pipe should draw water
from the middle
There must be drain pipe for wash out
during cleaning
The tank must rest on strong and firm
base.
The inside surface should be non toxic
Floor to slope towards drain outlet
1
2
3
4 2. Inlet 3. Overflow
4. Outlet5.Drainpipe
7.Non- toxic
inside
6.Strong base
 Tanks should be properly covered to
prevent algal growth.
Inlet pipe should come from a level
that is higher than the tank top.
There must be overflow pipe –
Covered with mesh
The outlet pipe should draw water
from the middle
There must be drain pipe for wash out
during cleaning
The tank must rest on strong and firm
base.
The inside surface should be non toxic
Floor to slope towards drain outlet
4
8.Floor with slope
5
6
7
8

54. Design Procedure
Analyze Meteorological Data
Analyze geological & hydrological data
Analyze the site plan
Objective of designing RWH ? II What is the analysis required?
Pay back Period Calculation
Cost Estimation
Design of storage and recharge system
Identify RWH potential
Determination of water Demand

55. Operation and Maintenance

56. RWH project
Req.1
RequirementRequirement
justifiedjustified
Req.2
Space AvailableSpace Available
Req.2
Sufficient BudgetSufficient Budget
Planning &Planning &
Designing StageDesigning Stage
(5%)(5%)
Construction StageConstruction Stage
(80%)(80%)
• Excavation/Retrofitti
ng
• Material
• Plumbing
• Storage facility
• Conveyance system
Capital & O&M costCapital & O&M cost
(15%)(15%)
Consultation /
Labour/Salary
Construction StageConstruction Stage
(80%)(80%)
• Excavation/Retrofitti
ng
• Material
• Plumbing
• Storage facility
• Conveyance system
Capital & O&M costCapital & O&M cost
(15%)(15%)
Consultation /
Labour/Salary
RWH project impact
Benefits
Socio-economic factors
Cost reduced on water
purchase
Health benefits

57. Allocation of BudgetAllocation of Budget
Broadly, planning , designing, implementation and O& M activities comprise the
measure heads for budgeting a RWH system.
Planning and Designing 5%
Implementation 80%
Operation and Maintenance 15%

59. a. Planning & designing cost (5%)a. Planning & designing cost (5%)
• Data collection and analysis
• Meteorological parameters
• Site plan and Catchment area
• Drainage pattern (natural/artificial)
 Catchment mapping (for big projects)
• Survey : location, geology/soil, slopes, drainage line &
sewage discharge arrangements
• Water demand assessment & storage potential planning
• Design of storage/recharge structures
• Data collection and analysis
• Meteorological parameters
• Site plan and Catchment area
• Drainage pattern (natural/artificial)
 Catchment mapping (for big projects)
• Survey : location, geology/soil, slopes, drainage line &
sewage discharge arrangements
• Water demand assessment & storage potential planning
• Design of storage/recharge structures

60. b. The installation cost : Implementation (80%)b. The installation cost : Implementation (80%)
• Excavation
• Civil work (retrofitting of catchment, brick work, collection chambers,
sedimentation tanks, underground storage tanks, recharge wells,
trenches, pits etc.)
• Storage tanks (ready-made, construction)
• Filter media
• Inter connecting pipes
• Gutter
• First flush systems
• Excavation
• Civil work (retrofitting of catchment, brick work, collection chambers,
sedimentation tanks, underground storage tanks, recharge wells,
trenches, pits etc.)
• Storage tanks (ready-made, construction)
• Filter media
• Inter connecting pipes
• Gutter
• First flush systems
Recharge Structure / Storage Structure with filtration and conveyance
system

61. c. Operation & Maintenance (15%)c. Operation & Maintenance (15%)
Expenditure for o & m in term of the following parameters:
• Cleaning/replacing filter media (sand, gravels, pebbles, charcoal, jute Choir
etc.)
• Removal of silt
• Repair leaking tanks / cracks at catchment and tanks
• Water quality tests (TDS, TSS, minerals, bacteriological parameters)
• This activity needs to be done twice a year : pre monsoon and post
monsoon for sustainability and efficacy
• Salary payment to care taker/operator
• O&M is necessary for the community level intervention. However, for
individual household it may not be significant in terms of cost
Expenditure for o & m in term of the following parameters:
• Cleaning/replacing filter media (sand, gravels, pebbles, charcoal, jute Choir
etc.)
• Removal of silt
• Repair leaking tanks / cracks at catchment and tanks
• Water quality tests (TDS, TSS, minerals, bacteriological parameters)
• This activity needs to be done twice a year : pre monsoon and post
monsoon for sustainability and efficacy
• Salary payment to care taker/operator
• O&M is necessary for the community level intervention. However, for
individual household it may not be significant in terms of cost

62. Retrofitting / new construction
 It costs more to retrofit an existing building for a RWH
system.
 Cost can be considerably reduced if RWH system is
included during the construction of the establishment.
Terrain (Geology), and meteorological parameters,
climate
Terrain affects cost e.g. excavation and drilling in hard rock terrain is >
expensive compared to alluvium
 Meteorological conditions affect cost for storage. If the intensity of rain
is high, it requires larger diameter conduit system and increases the
cost
 Climatic conditions especially coastal regions require painting, rust
proof arrangements for RWH project
Cost efficient design criteriaCost efficient design criteria
Terrain (Geology), and meteorological parameters,
climate
Terrain affects cost e.g. excavation and drilling in hard rock terrain is >
expensive compared to alluvium
 Meteorological conditions affect cost for storage. If the intensity of rain
is high, it requires larger diameter conduit system and increases the
cost
 Climatic conditions especially coastal regions require painting, rust
proof arrangements for RWH project

63. CCosting for a primary schoolosting for a primary school
1. Design and Data collection= Rs.10,000
2.Construction Cost
-Recharge pit (quantity 1)
- 100mm PVC pipe ,15m =Rs.3000
- Boring =Rs.3000
- Stone, sand, gravel =Rs.4000
- Brick wall,4x3x3 =Rs.25,000
- Manhole cover =Rs.5000
 Total - Rs.40,000
CCosting for a primary schoolosting for a primary school
1. Design and Data collection= Rs.10,000
2.Construction Cost
-Recharge pit (quantity 1)
- 100mm PVC pipe ,15m =Rs.3000
- Boring =Rs.3000
- Stone, sand, gravel =Rs.4000
- Brick wall,4x3x3 =Rs.25,000
- Manhole cover =Rs.5000
 Total - Rs.40,000

64. -Storage Cost
- Plastic tank,2000l =Rs.20,000
- RCC base =Rs.5000
- Conveyance pipe 20rft =Rs.2000
 Total - Rs.27,000
3. Capital, operation & maintenance cost = Rs.23,000
 Overall Cost = Design+ Construction +O & M
=10,000+1,07,000+ 23,000
=Rs. 1,40,000
-Storage Cost
- Plastic tank,2000l =Rs.20,000
- RCC base =Rs.5000
- Conveyance pipe 20rft =Rs.2000
 Total - Rs.27,000
3. Capital, operation & maintenance cost = Rs.23,000
 Overall Cost = Design+ Construction +O & M
=10,000+1,07,000+ 23,000
=Rs. 1,40,000

65.  Water Cost per tanker (10 cum) =Rs.1000
 For 1 cum charge =Rs.100
 RWH for storage and recharge (annual) =300 cum
 Savings per year =200x100 =Rs. 30,000
 Pay back period =1,40,000/30,000
=5 years
Pay Back Period
 Water Cost per tanker (10 cum) =Rs.1000
 For 1 cum charge =Rs.100
 RWH for storage and recharge (annual) =300 cum
 Savings per year =200x100 =Rs. 30,000
 Pay back period =1,40,000/30,000
=5 years