planning & designining rain water harvesting syst

8/13/2019 Planning & Designining Rain Water Harvesting Syst.

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PROJECT REPORT

ON

Planning and Designing Rain Water Harvesting System

Premnagar dehradun

DEPARTMENT OF CIVIL ENGINEERING

JB INSTITUTE OF TECHNOLOGY

DEHRADUN, UTTRAKHAND (248007)

[2013-2014]

Submitted By:

ABHIRAJ KUMAR PATHAK

Aditya Painyuli Amit Purohit

Balkrishana Tamta Deepak Singh

Himanshu Negi Sonali Rawat

Guided By:Mr. Subhash Chamoli


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On

Planning and Designing Rain Water Harvesting System

Premnagar dehradun

In partial fulfilment of requirements for the degree of

Bachelor of Technology

In

CIVIL ENGINEERING

SUBMITTED TO: SUBMITTED BY:

Prof. Sanjeev Gill (H.O.D) Abhiraj Kumar Pathak

Civil Engineering Department. Aditya Painyuli

JBIT,Dehradun Amit Purohit

Balkrishana Tamta

Deepak Singh

Himanshu Negi

Sonali Rawat


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DECLARATIONWE HEREB Y CERTIFY THAT THE REPORT EN TITLED PLANNING DESIGNING RAIN WATER HARVESTING SYSTEM

PREMNAGAR DEHRADUN IS SUB MITTED ,IN PARTIAL FULFILMEN T OF THE REQUIREMEN T FOR THE AW ARD O F DEGREE OFB ACHELOR OF TECHN OLOGY IN C IVIL EN GIN EERIN G ,T O JB INSTITUTE O F T E C H N O LO G Y U N D E R U T T A R A K H A N DT E C H N I C A L UNIVERSITY),DEHRADUN COMPRISES ON LY ORIGIN AL W ORK .

T HE MATTER EMB EDDED IN THIS REPORT IS O RIGIN AL AN D HAS N OT B EEN SUB MITTED EARLIER FOR THE AW ARD OF AN YOTHER DEGREE O F THIS OR AN Y UN IVERSITY.

ABHIRAJKUMARPATHAK (61530107002)ADITYAPAINYULI (10530107005)AMITPUROHIT (10530107008)BALKRISHANATAMTA (61530107004)HIMANSHUNEGI (10530102015)DEEPAKSINGH (10530107013)SONALIRAWAT (61530107012)

CERTIFIC TE


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his is to certify that the project work entitled

PLANNING DESIGNING RAIN WATER HARVESTING SYSTEM PREMNAGARDEHRADUN is a bonafide work carried out by ABHIRAJ KUMAR PATHAKcandidates of the B.Tech Civil Engineering from JB Institute of

Technology , Dehradun, affiliated to Uttarakhand Technical

University, Dehradun, under my guidance and supervision.

Mr. Subhash Chamoli Prof. Sanjeev Gill

{ Assistant Professor} {HOD Civil Engineering}

ExternalExaminer

(Signature)

Abstract


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Along the path of water flowing in a river basin are many water-related human

interventions that modify the natural systems. Rainwater harvesting is one such

intervention that involves harnessing of water in the upstream catchment. Increased water

usage at upstream level is an issue of concern for downstream water availability to

sustain ecosystem services. . To address this problem a technique was developed for

small scale farmers with the objective of harnessing rainwater for crop production.

However, the hydrological impact of a wider adoption of this technique by farmers has

not been well quantified. In this regard, the SWAT hydrological model was used to

simulate the hydrological impact of such practices. The scenarios studied were: (1)

Baseline scenario, based on the actual land use of 2000, which is dominated by pasture

(combination of natural and some improved grass lands) (PAST); (2) Partial conversion

of Land use 2000 (PAST) to conventional agriculture (Agri-CON); and (3) Partial

conversion of Land use 2000 (PAST) to in-field rainwater harvesting which was aimed at

improving the precipitation use efficiency (Agri-IRWH).


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CKNOWLEDGEMENTThe satisfaction and euphoria that accompanies the successful completion of any taskwould be incomplete without the mention of the people who made it possible whoseconstant guidance encouragement and support fructified my effort with success.

I consider it my privilege to express my gratitude and respect to all those who guidedme in the completion of my seminar report.

I would like to thank Prof.Sanjeev Gill Head of Department Civil Engineering forproviding me this valuable opportunity of presenting the seminar on Assessment ofPlanning and Designing Rain Water Harvesting System which has not onlyenhanced my knowledge about the subject but also increased my confidence level.

I am indebted to my mentor Mr. Subhash Chamoli for guiding me throughout thepreparation of my seminar. Last but not the least I would like to thank God myparents and colleagues for helping me directly or indirectly in the successfulcompletion of the project.Abhiraj Kumar pathak Aditya Painyuli

Amit Purohit Balkrishana Tamta

Deepak Singh Himanshu Negi

Sonali Rawat


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CONTENTS

1.1 Introduction

1.1.1 Rainwater Harvesting1.1.2 Why Rain Water Harvesting?

1.2. Rainwater Harvesting Feasibility Criteria

1.2.1 Plumbing Code1.2.2 Mechanical, Electrical, Plumbing (Mep

1.2.3 Water Use

1.2.4 Available Space

1.2.5 Site Topography

1.2.6 Available Hydraulic Head1.2.7 Water Table

1.2.8 Soils

1.2.9 Proximity Of Underground Utilities1.2.10 Contributing Drainage Area

1.2.11 Contributing Drainage Area Material

1.2.12 Water Quality Of Rainwater1.2.13 Hotspot Land Uses

1.2.14 Setbacks From Buildings

1.2.15 Vehicle Loading

1.2.16 Discharge To Combine Sewer System

1.3. Rainwater Harvesting Conveyance Criteria1.3.1 Collection And Conveyance

1.3.2 Overflow1.4. Rainwater Harvesting Pretreatment Criteria

1.4.1 First Flush Diverters

1.4.2 Leaf Screens1.4.3 Roof Washers

1.4.4 Vortex Filters

1.5 Criteria For Selection Of Rainwater Harvesting Technologies

1.6 Components Of A Rooftop Rainwater Harvesting System1.6.1 A Collection Or Catchment System

1.6.2 A Conveyance System Is Required To Transfer The Rainwater From The Roof

1.7 The Design Criteria Of A Sorage Tank

1.7.1 Available Space1.7.2 Site Topography1.7.3 Available Hydraulic Head

1.7.4 Water Table1.7.5 Soil

1.7.6 Proximity Of Underground Utilities


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1.7.7 Contributing Drainage Area

1.7.8 Water Quality Of Rainwater

1.7.9 Hotspot Land Uses1.7.10 Contributing Drainage Area Material

1.8 Rainwater Harvesting In Lpu Complex

1.9 Design Capacity Of Storage Tank2.1 Rainwater Harvesting Pretreatment Criteria2.2 Filtration Systems And Settling Tanks

2.3 Primary Treatment Of Rain Water

2.4 Secondary Treatment

2.4.1 Lab Testing On Rain Water Harvesting In prem nagar2.5 Experiment-2

2.6 Tertiary Treatment

Disinfection Technologies

Storage Tank Or Cistern To Store Harvested Rainwater2.6.3 Delivery System

2.6.3 Storage Tanks Or Reservoirs2.7 Storage Reservoirs For Domestic Rainwater Harvesting Are Classified In Two Categories

3.1 Rain Water Harvesting Techniques3.2 Urbanization Effects On Groundwater Hydrology

3.2.1 Methods Of Artificial Recharge In Urban Areas

3.2.2 Computation Of Artificial Recharge From Roof Top Rainwater Collection3.2.3 Benefits Of Artificial Recharge In Urban Areas

3.3 How It Works

Roof Catchments

Section Through Typical Gutter3.4 Harvesting Rainwater Harnessing Life

3.5 Attributes Of Groundwater3.5.1 Recharge Shafts3.5.2 Lateral Shafts With Bore Wells

3.5.3 Spreading Techniques

3.5.4 First Flush And Filter Screens3.5.5 Rainwater Harvesting Efficiency

3.6 Some Useful Data

3.6.1 Climatological Data

3.6.2 Irrigation3.6.3 Ground Water Potential (As On 31.03.2004)

4.1 Geomorphology And Soils

4.2 Hydrometeorology4.3 Hydrology And Surface Water Utilisation4.4 Agriculture

4.5 Hydrogeology

4.6 Water Level Behavior4.7 Ground Water Flow

4.8 Drinking Water Supply

4.9 Tube Well Irrigation


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5.1 Designing A Rainwater Harvesting System

5.2 Typical Domestic Rwh Systems

5.2.1storage Tanks And Cisterns5.2.2 Domestic Storage Tanks

5.2.3 Ferro Cement Tanks

5.2.4 Rock Catchments5.2.5 Cultural Acceptability5.6 Maintenance

5.6.1 Regulations And Technical Standards

5.6.2 Types Of Rainwater Use5.7 Advantage Of Rainwater Harvesting

5.8 Disadvantages

5.9 Effectiveness Of Technology

Reference

Name of figure. Page No.Vortex Filters

Components of a rooftop rainwater harvesting system

Rainwater harvesting in prem nagar dehradunBlock 55

Block 56

Water supply by pipeSand filter

PH meter

Turbidity meterStorage reservoirs for domestic rainwater harvesting

Rock catchmentsGraphical methode of determine the required storage volume for a rain water

1.1 Introduction:


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1.1.1 Rainwater Harvesting

Rainwater harvesting systems store and release rainfall for future use. Rainwater that falls on

a rooftop or other impervious surface is collected and conveyed into an above- or belowground

storage tank (also referred to as a cistern or rain tank), where it can be used for nonpotablewater uses and on-site storm water disposal/infiltration. Non-potable uses may

include landscape irrigation, exterior washing (e.g. car washes, building facades, sidewalks,

street sweepers, fire trucks), flushing of toilets and urinals, fire suppression (sprinkler

systems), supply for cooling towers, evaporative coolers, fluid coolers and chillers,

supplemental water for closed loop systems, steam boilers, replenishment of water features

and water fountains, distribution to a green wall or living wall system, laundry, and delayed

discharge to the combined sewer system.

In many instances, rainwater harvesting can be combined with a secondary (down-gradient)

storm water practice to enhance storm water retention and/or provide treatment of overflow

from the rainwater harvesting system. Some candidate secondary practices include:

Disconnection to a pervious or conservation area

Overflow to bio retention practices

Overflow to infiltration practices

Overflow to grass channels or dry swales

By providing a reliable and renewable source of water to end users, rainwater harvesting

systems can also have environmental and economic benefits beyond storm water

management (e.g. increased water conservation, water supply during drought and mandatory

municipal water supply restrictions, decreased demand on municipal or groundwater supply,

decreased water costs for the end-user, potential for increased groundwater recharge).

Seven primary components of a rainwater harvesting system include:

(1) Drainage area

(2) Collection and conveyance system (i.e. gutter and downspouts)

(3) Pre-screening and first flush diverter

(4) Storage tank

(5) Water quality treatment (as required by TRAM)

(6 )Distribution system

(7) Overflow, filter path or secondary storm water retention practice


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1.2.4 Available Space: - Adequate space is needed to house the storage tank and any

overflow. Space limitations are rarely a concern with rainwater harvesting systems if they are

considered during the initial building design and site layout of a residential or commercial

development. Storage tanks can be placed underground, indoors, on rooftops that are

structurally designed to support the added weight, and adjacent to buildings. Designers can

work with architects and landscape architects to creatively site the tanks. Underground

utilities or other obstructions should always be identified prior to final determination of the

tank location.

1.2.5 Site Topography: - Site topography and storage tank location should be considered

as they relate to all of the inlet and outlet invert elevations in the rainwater harvesting system.

The final invert of the outlet pipe from the storage tank must match the invert of the receiving

mechanism (e.g. natural channel, storm drain system) that receives this overflow. The

elevation drops associated with the various components of a rainwater harvesting system and

the resulting invert elevations should be considered early in the design, in order to ensure that

the rainwater harvesting system is feasible for the particular site.

Site topography and storage tank location will also affect pumping requirements. Locating

storage tanks in low areas will make it easier to get water into the cisterns; however, it will

increase the amount of pumping needed to distribute the harvested rainwater back into the

building or to irrigated areas situated on higher ground. Conversely, placing storage tanks at

higher elevations may require larger diameter pipes with smaller slopes but will generally

reduce the amount of pumping needed for distribution. It is often best to locate a cistern close

to the building or drainage area, to limit the amount of pipe needed.

1.2.6 Available Hydraulic Head: - The required hydraulic head depends on the

intended use of the water. For residential landscaping uses, the cistern should be sited upgradient

of the landscaping areas or on a raised stand. Pumps are commonly used to convey

stored rainwater to the end use in order to provide the required head. When the water is being

routed from the cistern to the inside of a building for non-potable use, often a pump is used to

feed a much smaller pressure tank inside the building, which then serves the internal water

demands. Cisterns can also use gravity to accomplish indoor residential uses (e.g. laundry)


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that do not require high water pressure.

1.2.7 Water Table:- Underground storage tanks are most appropriate in areas where the

tank can be buried above the water table. The tank should be located in a manner that is not

subject it to flooding. In areas where the tank is to be buried partially below the water table,

special design features must be employed, such as sufficiently securing the tank (to keep it

from floating), and

Conducting buoyancy calculations when the tank is empty, the tank may need to be secured

appropriately with fasteners or weighted to avoid uplift buoyancy. The tank must also be

installed according to the tank manufacturers specifications.

1.2.8 Soils: - Storage tanks should only be placed on native soils or on fill in accordance

with the manufacturer's guidelines. The bearing capacity of the soil upon which the cistern

will be placed must be considered, as full cisterns can be very heavy. This is particularly

important for above-ground cisterns, as significant settling could cause the cistern to lean or

in some cases to potentially topple. A sufficient aggregate, or concrete base, may be

appropriate depending on the soils. The pH of the soil should also be considered in relation to

its interaction with the cistern material.

1.2.9 Proximity of Underground Utilities: - All underground utilities must be taken

into consideration during the design of underground rainwater harvesting systems, treating all

of the rainwater harvesting system components and storm drains as typical storm water

facilities and pipes. The underground utilities must be marked and avoided during the

installation of underground tanks and piping associated with the system.

1.2.10 Contributing Drainage Area:- The contributing drainage area (CDA) to the

cistern is the impervious area draining to the tank. Rooftop surfaces are what typically make

up the CDA, but paved areas and landscaped areas can be used with appropriate treatment

(oil/water separators and/or debris excluders). Areas of any size, including portions of roofs,

can be used based on the sizing guidelines in this design specification. Runoff should be


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routed directly from the drainage area to rainwater harvesting systems in closed roof drain

systems or storm drain pipes, avoiding surface drainage, which could allow for increased

contamination of the water.

1.2.11 Contributing Drainage Area Material: - The quality of the harvested

rainwater will vary according to the roof material or drainage area over which it flows. Water

harvested from certain types of rooftops and CDAs, such as asphalt sealcoats, tar and gravel,

painted roofs, galvanized metal roofs, sheet metal, or any material that may contain asbestos

may leach trace metals and other toxic compounds. In general, harvesting rainwater from

such surfaces should be avoided. If a sealant or paint roof surface is desired, it is

recommended to use one that has been certified for such purposes by the National Sanitation

Foundation (ANSI/NSF standard).

1.2.12 Water Quality of Rainwater: - Designers should also note that the pH of

rainfall in the District tends to be acidic (ranging from 4.5 to 5.0), which may result in

leaching of metals from roof surfaces, tank lining or water laterals, to interior connections.

Once rainfall leaves rooftop surfaces, pH levels tend to be slightly higher, ranging from 5.5 to

6.0. Limestone or other materials may be added in the tank to buffer acidity, if desired.

1.2.13 Hotspot Land Uses: - Harvesting rainwater can be an effective method to

prevent contamination of rooftop runoff that would result from mixing it with ground-level

runoff from a storm water hotspot operation. In some cases, however, industrial roof surfaces

may also be designated as storm water hotspots.

1.2.14 Setbacks from Buildings: - Storage tank overflow devices should be designed

to avoid causing ponding or soil saturation within 10 feet of building foundations. Tanks

must be designed to be watertight to prevent water damage when placed near building

foundations.

1.2.15 Vehicle Loading: - Whenever possible, underground rainwater harvesting

systems should be placed in areas without vehicle traffic or be designed to support live loads


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from heavy trucks, a requirement that may significantly increase construction costs.

1.2.16 Discharge to Combine Sewer System: - Discharge of harvested rainwater to

the combined sewer system is considered an acceptable drawdown method to achieve

retention value. However, the drawdown must be limited to a rate which releases the SWRv

over at least 72 hours.

1.3. Rainwater Harvesting Conveyance Criteria

1.3.1 Collection and Conveyance: - The collection and conveyance system consists of

the gutters, downspouts, and pipes that channel rainfall into storage tanks. Gutters and

downspouts should be designed as they would for a building without a rainwater harvesting

system. Aluminum, round-bottom gutters and round downspouts are generally recommended

for rainwater harvesting. Minimum slopes of gutters should be specified. Typically, gutters

should be hung at a minimum of 0.5% for 2/3 of the length and at 1% for the remaining 1/3

of the length in order to adequately convey the design storm (e.g. Storm water Retention

Volume (SWRv)). If the system will be used for management of the 2-yr and 15-yr storms,

the gutters should be designed to convey the appropriate 2-yr and 15-yr storm intensities.

Pipes, which connect downspouts to the cistern tank, should be at a minimum slope of 1.5%

and sized/designed to convey the intended design storm, as specified above. In some cases, a

steeper slope and larger sizes may be recommended and/or necessary to convey the required

runoff, depending on the design objective and design storm intensity. Gutters and downspouts

should be kept clean and free of debris and rust.

1.3.2 Overflow: - An overflow mechanism should be included in the rainwater harvesting

system design in order to handle an individual storm event or multiple storms in succession

that exceed the capacity of the tank. Overflow pipe(s) should have a capacity equal to or

greater than the inflow pipe(s) and have a diameter and slope sufficient to drain the cistern

while maintaining an adequate freeboard height. The overflow pipe(s) should be screened to

prevent access to the tank by rodents and birds.

1.4. Rainwater Harvesting Pretreatment Criteria


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Pre-filtration is required to keep sediment, leaves, contaminants, and other debris from the

system. Leaf screens and gutter guards meet the minimal requirement for pre-filtration of

small systems, although direct water filtration is preferred. All pre-filtration devices should

be low-maintenance or maintenance-free. The purpose of pre-filtration is to significantly cut

down on maintenance by preventing organic buildup in the tank, thereby decreasing

microbial food sources.

For larger tank systems, the initial first flush must be diverted from the system before

rainwater enters the storage tank. Designers should note that the term first flush in

rainwater harvesting design does not have the same meaning as has been applied historically

in the design of storm water treatment practices. In this specification, the term first flush

diversion is used to distinguish it from the traditional storm water management term first

flush. The amount can range between the first 0.02 to 0.06 inchesand typically applies to

rooftop runoff.

The diverted flows (i.e. first flush diversion and overflow from the filter) must be directed to

an acceptable flow path that will not cause erosion during a 2-yr storm or to an appropriate

BMP on the property.

Various first flush diverters are described below. In addition to the initial first flush diversion,

filters have an associated efficiency curve that estimates the percentage of rooftop runoff that

will be conveyed through the filter to the storage tank. If filters are not sized properly, a large

portion of the rooftop runoff may be diverted and not conveyed to the tank at all. A design

intensity of 1 inch/hour (for design storm = SWRv) should be used for the purposes of sizing

pre-tank conveyance and filter components. This design intensity captures a significant

portion of the total rainfall during a large majority of rainfall events (NOAA, 2004). If the

system will be used for channel and flood protection, the 2-yr and 15-yr storm intensities

should be used for the design of the conveyance and pre-treatment portion of the system. For

the SWRv, a minimum of 95% filter efficiency is required. This efficiency includes the first

flush diversion. The Cistern Design Spreadsheet, discussed more in Section 1.2 assumes a

filter efficiency rate of 95% for the SWRv design storm. To meet the requirements to manage

the 2-year and 15-year storms, a minimum filter efficiency of 90% should be met.

1.4.1 First Flush Diverters: - First flush diverters direct the initial pulse of rainfall


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away from the storage tank. While leaf screens effectively remove larger debris such as

leaves, twigs, and blooms from harvested rainwater, first flush diverters can be used to

remove smaller contaminants such as dust, pollen, and bird and rodent feces. Simple first

flush diverters require active management, by draining the first flush water volume to a

pervious area following each rainstorm. First flush diverters may be the preferred pretreatment

method if the water is to be used for indoor purposes. A vortex filter (see Figures

3.2.2) may serve as an effective pre-tank filtration device and first flush diverter.

1.4.2 Leaf Screens: - Leaf screens are mesh screens installed over either the gutter or

downspout to separate leaves and other large debris from rooftop runoff. Leaf screens must

be regularly cleaned to be effective; if not maintained, they can become clogged and prevent

rainwater from flowing into the storage tanks. Built-up debris can also harbor bacterial

growth within gutters or downspouts (TWDB, 2005).

1.4.3 Roof Washers: - Roof washers are placed just ahead of storage tanks and are used

to filter small debris from harvested rainwater (see Figure 3.2.3). Roof washers consist of a

tank, usually between 25 and 50 gallons in size, with leaf strainers and a filter with openings

as small as 30-microns. The filter functions to remove very small particulate matter from

harvested rainwater. All roof washers must be cleaned on a regular basis.


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1.4.4 Vortex Filters: - For large scale applications, vortex filters can provide filtering of

CDA rainwater from larger CDAs.

Rooftop rainwater harvesting at the household level is most commonly used for domestic

purposes. It is popular as a household option as the water source is close to people and thus

requires a minimum of energy to collect it. An added advantage is that users own maintain

and control their system without the need to rely on other community members.

1.5 Criteria for selection of rainwater harvesting technologiesSeveral factors should be considered when selecting rainwater harvesting systems for

domestic use:

Type and size of catchment area

Local rainfall data and weather pattern

Family size

Length of the drought period

Alternative water sources

Cost of the rainwater harvesting system.

When rainwater harvesting is mainly considered for irrigation, several factors should be taken

into consideration.

These include:

rainfall amounts, intensities, and evaporate-transpiration rates


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soil infiltration rate, water holding capacity, fertility and depth of soil

crop characteristics such as water requirement and length of growing period

hydrogeology of the site

Socio-economic factors such as population density, labour, costs of materials and

regulations governing water resources use.

1.6 Components of a rooftop rainwater harvesting system

Although rainwater can be harvested from many surfaces, rooftop harvesting systems are

most commonly used as the quality of harvested rainwater is usually clean following proper

installation and maintenance. The effective roof area and the material used in constructing the

roof largely influence the efficiency of collection and the water quality.

Rainwater harvesting systems generally consist of four basic elements:

1. A collection (catchment) area

2. A conveyance system consisting of pipes and gutters

3. A storage facility,


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4. A delivery system consisting of a tap or pump.

1.6.1 A collection or catchment system: - is generally a simple structure such as

roofs and/or gutters that direct rainwater into the storage facility. Roofs are ideal as

catchment areas as they easily collect large volumes of rainwater. The amount and quality of

rainwater collected from a catchment area depends upon the rain intensity, roof surface area,

type of roofing material and the surrounding environment. Roofs should be constructed of

chemically inert materials such as wood, plastic, aluminum, or fiberglass. Roofing materials

that are well suited include slates, clay tiles and concrete tiles. Galvanized corrugated iron

and thatched roofs made from palm leaves are also suitable. Generally, unpainted and

uncoated surface areas are most suitable. If paint is used, it should be non-toxic (no leadbased

paints).

1.6.2 A conveyance system is required to transfer the rainwater from the

roof: - catchment area to the storage system by connecting roof drains (drain pipes) and

piping from the roof top to one or more downspouts that transport the rainwater through a

filter system to the storage tanks. Materials suitable for the pipe work Include polyethylene

(PE) polypropylene (PP) or stainless steel. Before water is stored in a storage tank or cistern,

and prior to use, it should be Filtered to remove particles and debris. The choice of the

filtering system depends on The conditions. Low-maintenance filters with a good filter output

and high Water flow should be preferred. First flush systems whichfilter out the first rain

and diverts it away from the storage tank should be also installed. This will remove the

Contaminants in rainwater which are highest in the first rain shower.

1.7 THE DESIGN CRITERIA OF A SORAGE TANK

1.7.1 Available Space: - Adequate space is needed to house the storage tank and any

overflow. Space limitations are rarely a concern with rainwater harvesting systems if they are

considered during the initial building design and site layout of a residential or commercial

development. Storage tanks can be placed underground, indoors, on rooftops that are

structurally designed to support the added weight, and adjacent to buildings. Designers can

work with architects and landscape architects to creatively site the tanks. Underground


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utilities or other obstructions should always be identified prior to final determination of the

tank location.

1.7.2 Site Topography: - Site topography and storage tank location should be considered

as they relate to all of the inlet and outlet invert elevations in the rainwater harvesting system.

The final invert of the outlet pipe from the storage tank must match the invert of the receiving

mechanism (e.g. natural channel, storm drain system) that receives this overflow. The

elevation drops associated with the various components of a rainwater harvesting system and

the resulting invert elevations should be considered early in the design, in order to ensure that

the rainwater harvesting system is feasible for the particular site.

Site topography and storage tank location will also affect pumping requirements. Locating

storage tanks in low areas will make it easier to get water into the cisterns; however, it will

increase the amount of pumping needed to distribute the harvested rainwater back into the

building or to irrigated areas situated on higher ground. Conversely, placing storage tanks at

higher elevations may require larger diameter pipes with smaller slopes but will generally

reduce the amount of pumping needed for distribution. It is often best to locate a cistern close

to the building or drainage area, to limit the amount of pipe needed.

1.7.3 Available Hydraulic Head: - The required hydraulic head depends on the

intended use of the water. For residential landscaping uses, the cistern should be sited upgradient

of the landscaping areas or on a raised stand. Pumps are commonly used to convey

stored rainwater to the end use in order to provide the required head. When the water is being

routed from the cistern to the inside of a building for non-potable use, often a pump is used to

feed a much msmaller pressure tank inside the building, which then serves the internal water

demands. Cisterns can also use gravity to accomplish indoor residential uses (e.g. laundry)

that do not require high water pressure.

1.7.4 Water Table: - Underground storage tanks are most appropriate in areas where the

tank can be buried above the water table. The tank should be located in a manner that is not

subject it to flooding. In areas where the tank is to be buried partially below the water table,


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special design features must be employed, such as sufficiently securing the tank (to keep it from

floating), and conducting buoyancy calculations when the tank is empty. The tank may

need to be secured appropriately with fasteners or weighted to avoid uplift buoyancy. The

tank must also be installed according to the tank manufacturers specifications.

1.7.5 Soil: - Storage tanks should only be placed on native soils or on fill in accordance

with the manufacturer's guidelines. The bearing capacity of the soil upon which the cistern

will be placed must be considered, as full cisterns can be very heavy. This is particularly

important for above-ground cisterns, as significant settling could cause the cistern to lean or

in some cases to potentially topple. A sufficient aggregate, or concrete base, may be

appropriate depending on the soils. The pH of the soil should also be considered in relation to

its interaction with the cistern material.

1.7.6 Proximity of Underground Utilities: - All underground utilities must be taken

into consideration during the design of underground rainwater harvesting systems, treating all

of the rainwater harvesting system components and storm drains as typical storm water

facilities and pipes. The underground utilities must be marked and avoided during the

installation of underground tanks and piping associated with the system.

1.7.7 Contributing Drainage Area: - The contributing drainage area (CDA) to the

cistern is the impervious area draining to the tank. Rooftop surfaces are what typically make

up the CDA, but paved areas and landscaped areas can be used with appropriate treatment

(oil/water separators and/or debris excluders). Areas of any size, including portions of roofs,

can be used based on the sizing guidelines in this design specification. Runoff should be

routed directly from the drainage area to rainwater harvesting systems in closed roof drain

systems or storm drain pipes, avoiding surface drainage, which could allow for increased

contamination of the water.

1.7.8 Water Quality of Rainwater: - Designers should also note that the pH of

rainfall in the District tends to be acidic (ranging from 4.5 to 5.0), which may result in

leaching of metals from roof surfaces, tank lining or water laterals, to interior connections.


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Once rainfall leaves rooftop surfaces, pH levels tend to be slightly higher, ranging from 5.5 to

6.0. Limestone or other materials may be added in the tank to buffer acidity, if desired.

1.7.9 Hotspot Land Uses: - Harvesting rainwater can be an effective method to prevent

contamination of rooftop runoff that would result from mixing it with ground-level runoff

from a storm water hotspot operation. In some cases, however, industrial roof surfaces may

also be designated as storm water hotspots.

1.7.10 Contributing Drainage Area Material: - The quality of the harvested

rainwater will vary according to the roof material or drainage area over which it flows. Water

harvested from certain types of rooftops and CDAs, such as asphalt sealcoats, tar and gravel,

painted roofs, galvanized metal roofs, sheet metal, or any material that may contain asbestos

may leach trace metals and other toxic compounds. In general, harvesting rainwater from

such surfaces should be avoided. If a sealant or paint roof surface is desired, it is

recommended to use one that has been certified for such purposes by the National Sanitation

Foundation (ANSI/NSF standard).

1.8 Rainwater harvesting in Prem nagar

Location-block number 55, 56, 57

These three blocks are situated behind the prem nagar.


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Block 55

Block 56

General data about rainfall in prem nagar


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Area of one block = 1800m^2

Number of Block=03

Now total area =1800*3

=5400 m^2

Annual rainfall depth =.700m

Total number of peoples = 8000(approx)

1.9 Design capacity of storage tank

Total water collection= area *rain fall depth

=5400*0.7= 3780 m^3

Now total amount of water =3780000 liter

There will be 60% of rainfall used for rainwater harvesting= (3780000*60)/100=>2268000 lit

So loss of rain water => 3780000-2268000=1512000 liter

Total number of peoples= 8000

Per capita water demand =15 liter/person/day

Total water demand for drinking => 8000*15= 120000 liter/day

Total water demand for gardening and cleaning purpose =>2268000-120000= 2148000 liter

So total storage tank capacity =3780000 liter

Now we will install the tank in each block = (2268000/3) = 756000 liter

2.1 Rainwater Harvesting Pretreatment Criteria

Pre-filtration is required to keep sediment, leaves, contaminants, and other debris from the

system. Leaf screens and gutter guards meet the minimal requirement for pre-filtration of

small systems, although direct water filtration is preferred. All pre-filtration devices should

be low-maintenance or maintenance-free. The purpose of pre-filtration is to significantly cut

down on maintenance by preventing organic buildup in the tank, thereby decreasing

microbial food.

2.2 Filtration systems and settling tanks

There are a wide variety of systems available for treating water before, during and after

storage .The level of sophistication also varies, from extremely high-tech to very


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rudimentary. A German company, WISY, have developed an ingenious filter which fits into a

vertical downpipe and acts as both filter and first-flush system. The filter, s cleverly takes in

water through a very fine (~0.20mm) mesh while allowing silt and debris to continue down

the pipe. The efficiency of the filter is over 90%. This filter is commonly used in European

systems The simple trash rack has been used in some systems but this type of filter has a

number of associated problems: firstly it only removes large debris; and secondly the rack

can become clogged easily and requires regular cleaning. The sand-charcoal-stone filter is

often used for filtering rainwater entering a tank. This type of filter is only suitable, however,

where the inflow is slow to moderate, and will soon overflow if the inflow exceeds the rate at

which the water can percolate through the sand. Settling tanks and partitions can be used to

remove silt and other suspended solids from the water. These are usually effective where

used, but add significant additional cost if elaborate techniques are used. Many systems found

in the field real simply on a piece of cloth or fine mosquito mesh to act as the filter (and to

prevent mosquitoes entering the tank). Post storage filtration include such systems as the up

flow sand filter or the twin compartment candle filters commonly found in LDCs .Many

other systems exist and can be found in the appropriate water literature.


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Water supply by pipe

Rainwater harvesting is one of the most promising alternatives for supplying water in the face

of increasing water scarcity and escalating demand. The pressure on water supplies, increased

environmental impact from large projects and deteriorating water quality, constrain the ability

to meet the demand for freshwater from traditional sources. Rainwater harvesting presents an

opportunity for the augmentation of water supplies allowing t the same time for self-reliance

and sustainability.

2.3 Primary Treatment of Rain Water

Sand Filters

A sand bed filter is a kind of depth filter. Broadly, there are two types of filter for separating

particulate solids from fluids:

Surface filters, where particulates are captured on a permeable surface

Depth filters, where particulates are captured within a porous body of material

In addition, there are passive and active devices for causing solid-liquid separation such as

settling tanks, self-cleaning screen filters, hydro cyclones and centrifuges.


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There are several kinds of depth filter, some employing fibrous material and others

employing granular materials. Sand bed filters are an example of a granular loose media

depth filter. They are usually used to separate small amounts (


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Requirements: Buffer solutions pH 4 & 7, Digital pH Meter, Beakers, Conical Flask,

Glass Stirrer, Burette 50 ml, Standard Hydrochloric acid solution 0.001 M, Methyl orange

indicator.

Principle: The original definition of the PH = -log [H] is not exact, & cannot be determined

exactly by electrometric methods. The activity rather than the concentration of an ion

determines the e.m.f of a galvanic cell of the type commonly used to measure PH, hence PH

may be defined as PH = -log OH+

Where OH+ is the activity of the hydrogen ion, but even this quantity, as defined, is not

capable of precise measurement, since any cell of the type

H2, Pt | H+ (unknown) || salt bridge || reference electrode

Used for the measurement inevitably involves a liquid junction potential of more or less

uncertain magnitude.

Measurement of PH by the e.m.f. method gives values corresponding more closely to the

activity than the concentration of hydrogen ion. It can be shown that the PH value is nearly

equal tolog 1.1 OH+, hence

PH = PCH + 0.04

The modern definition of PH is an operational one and is based on the work of standardization

and the recommendation of USNBs. In UPAC definition the difference in PH between two

solutions a std and an unknown at the same temperature with the same reference electrode

and with hydrogen electrodes at the same hydrogen pressure is

PH (X) - PH (S) = EX - ES /2.3026RT/F

Where EX is the emf of the cell

H2, Pt | solution S || 3.5M KCL | reference electrode

& ES is the emf of the cell

Two Helectrode may be replaced by a single glass electrode which is transferred from one

cell to the other. The PH difference thus determined is a pure number. The PH scale is defined

by specifying the nature of the standard solution & assigning a PH value to it.

The modern PH meter is an electronic digital voltmeter, sealed to read PH directly, & may


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range from a comparatively simple hand-hold instrument, suitable for use in the field to more

elaborate bench models. A PH meter therefore, always includes a control so that with the

electrode assembly placed

In a buffer solution of known PH, the scale reading of the instrument can be adjusted to the

correct value.

If the cell emf is measured over a range of PH, all measurements at the same temp. & if the

readings are then repeated for a series of different temperatures, then on plotting the results as

a series of isothermal curves, we find that at same PH value (PHi) the cell emf is independent

of temp, PHi is called the isopotential PH.

Procedure

Preparation of buffer solutions

1. Dissolve 1 buffer (pH 4 or 7) tab/cap in 50ml Double distilled water taken in a glass

beaker.

2. Transfer the liquid into a 100ml volumetric flask.


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3. Wash twice the beaker with 20ml of double distilled water and add washings in

volumetric flask.

4. Make up the volume of volumetric flask up to the mark with double distilled water.

Calibration of instrument

1. Switch on & adjust temperature knob at ambient temp and set Calibrate & Slop knob

at mid position. Set instrument at pH mode.

2. Put pH 7 buffer solution below clean, activated & dry pH electrode attached with the

instrument.

3. Adjust the Calibrate knob till reading displays 7.00 & then remove and wash the pH

electrode and gently wipe with tissue paper.

4. Put the pH electrode in pH 4 buffer solution & adjust the slop know till reading

displays 4.00.

5. Now the instrument is calibrated and no any knob is disturbed till end of experiment.

Calculation of pH value

1. Filter the water sample if there is any visible turbidity or precipitate.

2. Put the pH electrode in water sample taken in a beaker & note the reading of display.

3. Repeat the process for 3 times and Note down the average of all 3 values.

Calculation of alkalinity of water sample

1. Fill burette with standard hydrochloric acid (0.001M)

2. Take 100ml filtered water sample in a conical flask and add 1-2 drops of methyl

orange indicator, the color of water becomes yellow.

3. Add drop wise standard HCl to the conical flask & view over white background till


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color changes from Yellow to Reddish

4. Note the reading & repeat the process for three times.

Observation Table

Calculations

Water sample = HCl Solution

N1 x V1 = N2 x V2

N1 x 100 = 0.001 x 11.0

N1= (0.001 x 11)/100

N1= 0.00011

Result

The value of water sample was recorded 10.04 and the alkalinity (Hydroxyl Ion

Concentration) of given water sample was found to be 0.00011 N.


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2.5 Experiment-2

Object To determine the turbidity of water sample using coagulant treatment.

Requirements Digital Nephlo Turbidity Meter, Beakers, Conical Flask, Glass Stirrer, 0.1M

Potash Alum soln.

Procedure

Addition of coagulant

1. Add 5.0ml of 0.1M Potash alum solution in 250ml of filtered water sample and stay

for 5 minutes.

2. Shake well the precipitate if formed to make a turbid solute

Calibration of instrument

1. Switch on & adjust NTU range button at 1000 NTU.

2. Put double distilled water in sample tube up to the mark for reference and set the NTU

reading with ZERO calibrate button to 0.00.

3. Replace the blank with Standard 100 NTU Solution and set the NTU reading with

NTU calibrate button to 100.

4. Again replace distilled water followed by standard turbid solution and set 0.00 &

100.0 receptively with corresponding knobs.


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Calculation of Turbidity

1. Fill the sample tube with coagulant treated water sample.

2. Note down the display reading.

3. Repeat the process for 3 times and Note down the average of all 3 values.

Observation Table

Calculations

Average NTU Value= (212+210+211)/3 = 211

Result

The Turbidity of water sample was found to be 211 NTU


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2.6 Tertiary Treatment

2.6.1 Disinfection Technologies :- Although there are numerous disinfection

technologies, some of them are more appropriate for home use than others. We recommend

that you consider using a combination of ultraviolet light and chlorine for the following

reasons.

Ultraviolet light (UV) is extremely effective against Cryptosporidium, but high doses are

required to inactivate some viral pathogens. In addition, UV systems do not maintain a

Disinfectant residual in your plumbing system.

Free chlorine is very effective against viruses but is virtually ineffective against

Cryptosporidium. In addition, it is easy to maintain and measure free chlorine residual in your

plumbing system.

If you do not want to maintain a disinfectant residual in your plumbing system, you may want

To consider using ozone as an alternative to UV, Like UV, ozone does not produce a longlasting

residual and will not provide any protection against bacterial regrowth in your

plumbing. However, it is effective against both parasites and viruses. The major reason that

we are not recommending ozone is that there is no ANSI/NSF standard for evaluating the

safety of ozone generators used for potable water applications. If you do decide to use ozone

as your disinfectant, be sure to use an ozone contact vessel that is certified in accordance with

ANSI/NSF Standard 61 requirements.

2.6.2 Storage tank or cistern to store harvested rainwater: - for use when

needed. Depending on the space available these tanks can be constructed above grade, partly

underground, or below grade. They may be constructed as part of the building, or may be

built as a separate unit located some distance away from the building. The storage tank

should be also constructed of an inert material such as reinforced concrete, Ferro cement

(reinforced steel and concrete), fiberglass, polyethylene, or stainless steel, or they could be

made of wood, metal, or earth. The choice of material depends on local availability and

affordability. Various types can be used including cylindrical Ferro cement tanks, mortar jars

(large jar shaped vessels constructed from wire reinforced mortar) and single and battery


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(interconnected) tanks. Polyethylene tanks are the most common and easiest to clean and

connect to the piping system. Storage tanks must be opaque to inhibit algal growth and

should be located near to the supply and demand points to reduce the distance water is

conveyed. Water flow into the storage tank or cistern is also decisive for the quality of the

cistern water. Calm rainwater inlet will prevent the stirring up of the sediment. Upon leaving

the cistern, the stored water is extracted from the cleanest part of the tank, just below the

surface of the water, using a floating extraction filter. A sloping overflow trap is necessary to

drain away any floating matter and to protect from sewer gases. Storage tanks should be also

kept closed to prevent the entry of insects and other animals.

2.6.3 Delivery system: - which delivers rainwater and it usually includes a small pump, a

Pressure tank and a tap, if delivery by means of simple gravity on site is not feasible.

Disinfection of the harvested rainwater, which includes filtration and/or ozone or UV

disinfection, is necessary if rainwater is to be used as a potable water source.

2.6.4 Storage tanks or reservoirs: - The storage reservoir is usually the most

expensive part of the rainwater harvesting system such that a careful design and construction

is needed. The reservoir must be constructed in such a way that it is durable and watertight

and the collected water does not become contaminated.

All rainwater tank designs should include as a minimum requirement:

1. A solid secure cover

2. A coarse inlet filter

3. An overflow pipe

4. A manhole, sump, and drain to facilitate cleaning

5. An extraction system that does not contaminate the water, e.g. a tap or pump.


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2.7 Storage reservoirs for domestic rainwater harvesting are classified in

two categories: -

1. Surface or above-ground tanks, most common for roof collection,

2. Sub-surface or underground tanks, common for ground catchment systems.

Materials and design for the walls of sub-surface tanks or cisterns must be able to resist the

soil and soil water pressures from outside when the tank is empty. Tree roots can also damage

the structure below ground. The size of the storage tank needed for a particular application is

mainly determined by the amount of water available for storage (a function of roof size and

local average rainfall), the amount of water likely to be used (a function of occupancy and

use purpose) and the projected length of time without rain (drought period).

3.1 Rain water harvesting techniques


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There are two main techniques of rain water harvestings.

(1) Storage of rainwater on surface for future use.

(2) Recharge to ground water.

(1) The storage of rain water on surface is a traditional techniques and structures used were

underground tanks, ponds, check dams, weirs etc. Recharge to ground water is a new concept

of rain water harvesting and the structures generally used are: -

Pits: - Recharge pits are constructed for recharging the shallow aquifer. These are

constructed 1 to 2 m, wide and to 3 m. deep which are back filled with boulders, gravels,

coarse sand.

Trenches: - These are constructed when the permeable stream is available at shallow

depth. Trench may be 0.5 to 1 m. wide, 1 to 1.5m. Deep and 10 to 20 m. long depending up

availability of water, these are back filled with filter materials.

Dug wells: - Existing dug wells may be utilized as recharge structure and water should

pass through filter media before putting into dug well.

Hand pumps: - The existing hand pumps may be used for recharging the shallow/deep

aquifers, if the availability of water is limited. Water should pass through filter media before

diverting it into hand pumps.

Recharge wells: - Recharge wells of 100 to 300 mm. diameter are generally constructed

for recharging the deeper aquifers and water is passed through filter media to avoid choking

of recharge wells.

3.2 Urbanization effects on Groundwater Hydrology: -

Increase in water demand

More dependence on ground water use

Over exploitation of ground water

Increase in run-off, decline in well yields and fall in water levels

Reduction in open soil surface area

Reduction in infiltration and deterioration in water quality

3.2.1 Methods of artificial recharge in urban areas: -

Water spreading


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Recharge through pits, trenches, wells, shafts

Rooftop collection of rainwater

Road top collection of rainwater

Induced recharge from surface water bodies.

3.2.2 Computation of artificial recharge from Roof top rainwater

collection: -

Factors taken for computation.

Roof top area 100 sq .m. for individual house and 500 sq .m. for multi

storied building.

Average annual monsoon rainfall - 780 mm.

Effective annual rainfall contributing to recharge 70% - 550 mm.

3.2.3 Benefits of Artificial Recharge in Urban Areas: -

Improvement in infiltration and reduction in run-off.


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Improvement in groundwater levels and yields.

Reduces strain on Special Village Panchayats/ Municipal/Municipal Corporation

water supply.

Improvement in groundwater quality.

Estimated quantity of additional recharge from 100 sq. m. roof top area is 55.000

liters.

3.3 How it works

3.3.1 Roof catchments: -

Rainwater can be collected from most forms of roof. Tiled roofs, or roofs sheeted with

corrugated mild steel etc are preferable, since they are the easiest to use and give the cleanest

water. Thatched or palm leafed surfaces are also feasible; although they are difficult to clean

and can often taint the run-off. Asbestos sheeting or lead-painted surfaces should be avoided.

The rainwater is collected in guttering placed around the eaves of the building. Low cost

guttering can be made up from 22 gauge galvanized mild steel sheeting, bent to form a V

and suspended by galvanized wire stitched through the thatch or sheeting.

3.3.2 Section through typical gutter: -


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The guttering drains to a down-pipe which discharges into a storage tank. The down-pipe

should be made to swivel so that the collection of the first run-off can be run to waste (the

first foul flush), thus preventing accumulated bird droppings, leaves, twigs and other

vegetable matter, as well as dust and debris, from entering the storage tank. Sometimes a

collecting box with a mesh strainer (and sometimes with additional filter media) is used to

prevent the ingress of potential pollutants.


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Alternatively, a foul flush box, which can be drained separately, may be fitted between the

down-pipe and the storage tank. The run-off from a roof is directly proportional to the

quantity of rainfall and the plan area of the roof. For every one millimeter of rain a square

meter of roof area will yield one litter of water, less evaporation, spillage losses and wind

effects. The guttering and downpipes should be sized so as to be capable of carrying peak

volume of run off; in the tropics this can occur during high intensity storms of short duration.

3.4 harvesting rainwater harnessing life:A noble goal a common responsibility: - Ground water exploitation is

inevitable is Urban areas. But the groundwater potential is getting reduced due to

urbanization resulting in over exploitation. Hence, a strategy to implement the

groundwater recharge, in a major way need to be launched with concerted efforts by

various Governmental and Non-Governmental Agencies and Public at large to build

up the water table and make the groundwater resource, a reliable and sustainable

source for supplementing water supply needs of the urban dwellers.

3.5 Attributes of groundwater:

There is more ground water than surface water.

Ground water is less expensive and economic resource.

Ground water is sustainable and reliable source of water supply.

Ground water is relatively less vulnerable to pollution.


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Ground water is usually of high bacteriological purity.

Ground water is free of pathogenic organisms.

Ground water needs little treatment before use.

Ground water has no turbidity and color .

Ground water has distinct health advantage as art alternative for lower

sanitary quality surface water.

Ground water is usually universally available.

Ground water resource can be instantly developed and used.

There are no conveyance losses in ground water based supplies.

Ground water has low vulnerability to drought.

Ground water is key to life in arid and semi-arid regions.

Ground water is source of dry weather flow in rivers and streams.

3.5.1 Recharge Shafts: - For recharging the shallow aquifer which is located below

clayey surface, recharge shafts of 0.5 to 3 m. diameter and 10 to 15 m. deep are constructed

and back filled with boulders, gravels & coarse sand.

3.5.2 Lateral shafts with bore wells: - For recharging the upper as well as deeper

aquifers lateral shafts of 1.5 to 2 m. wide & 10 to 30 m. long depending upon availability of

water with one or two bore wells is constructed. The lateral shafts are back filled with

boulders, gravels & coarse sand.

3.5.3 Spreading techniques: - When permeable strata start from top then this technique

is used. Spread the water in streams/Nalas by making check dams, nala bunds, cement plugs,

gabion structures or a percolation pond may be constructed.

3.5.4 First flush and filter screens: -The first rain drains the dust, bird droppings,

leaves, etc. which are found on the roof surface. To prevent these pollutants from entering the

storage tank, the first rainwater containing the debris should be diverted or flushed.

Automatic devices that prevent the first 20-25 liters of runoff from being collected in the

storage tank are recommended. Screens to retain larger debris such as leaves can be installed


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in the down-pipe or at the tank inlet. The same applies to the collection of rain runoff from a

hard ground surface. In this case, simple gravel-sand filters can be installed at the entrance of

the storage tank to filter the first rain.

3.5.5 Rainwater harvesting efficiency :- The efficiency of rainwater harvesting

depends on the materials used, design and construction, maintenance and the total amount of

rainfall. A commonly used efficiency figure, runoff coefficient, which is the percentage of

precipitation that appears as runoff, is 0.8. For comparison, if cement tiles are used as a

roofing material, the year-round roof runoff coefficient is about 75%, whereas clay tiles

collect usually less than 50% depending on the harvesting technology. Plastic and metal

sheets are best with an efficiency of 80-90%. For effective operation of a rainwater

harvesting system, a well-designed and carefully constructed gutter system is also crucial.

90% or more of the rainwater collected on the roof will be drained to the storage tank if the

gutter and down-pipe system is properly fitted and maintained. Common materials for gutters

and down-pipes are metal and plastic, but also cement-based products, bamboo and wood can

be used.

3.6 Some useful data

Geographical Area : 2662 Sq. km

Blocks : 10 (prem nagar west)

Rural Population as % of Total Population: 52.52%


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Urban Population as % of Total Population: 47.48%

Prem nagar, the central most city of dehradun is located between 30o 59: 31o 37 north

latitudes and 75o 04 : 75o 57 east longitudes. Total geographical area of the district is 2662

sq.km. Administratively, the district is controlled by dehradun division. . The total population of


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district was 19,53,508 as per 2001 Census, which constitutes 8.04 % of the total population of

the prem nagar. dehradun district has observed a growth (1991-2001) rate of 18.40 %. Population

density of district is 742 person/sq.km having a literacy rate of 77.91%

4.1 Geomorphology and soils

The district forms a part of Beas Sub basin of Indus basin.The district is part of Bist Doab

Tract, which is inter alluvial plain tons River. Physiographically, the

district is characterised by two distinct features i.e. vast upland plain and Satluj flood plain.

The width of the flood plain varies according to the amount of shift experienced by the river.

It is widest in the dehradunr tehsil. The district is mainly drained by the river tons and dehradun has two

types of

soils viz-tropical arid brown and arid brown soils (solonized). Tropical brown soils are found

In major parts of the district whereas arid brown soils are found in south western part of the

district especially in dehradun .

Type of soil is found.

4.2 Hydrometeorology

Climate of the district can be classified as tropical and dry sub humid. The area receives

normal annual rainfall is about 701 mm which is spread over 35 rainy days. 70% of rainfall

occurs during south-west monsoon.

4.3 Hydrology and surface water utilization

The Bist Doab Canal System is the major source of canal irrigation. The network of dehradun

branch (irrigate northern and central parts) and Phillaur distributary of dehradun branch

((irrigate southern parts of the district). In all there are 41 canals having total length of 604.40

km. of which Best Doab canal is 43 km long. Out of 2,27,423 ha net irrigated area, 26,755 ha

is irrigated by canal and rest by ground water. At present, two irrigation projects are in

operation. One project is for Remodeling of Phillaur distributry system in prem nagar area and


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other project is for Construction of super passage over Nasrala choe near prem nagar. The main

purpose of the irrigation project is to increase the capacity of the channel by 20% and to

avoid the damages to the crops and adjoining abadies during flood season.

4.4 Agriculture

Net area sown in the district is 2,27,994 ha which constitutes 86% of the total area. Area

sown more than once is 1,85,285 ha bringing the total cropped area (Gross sown area) to

4,13,279 ha. Paddy constitutes main kharif crop whereas the wheat is the main Rabi crop.

Perusal of historical data reveals that the paddy cultivation has increased about 85 times since

1950-51 against wheat cultivation, which has increased only 1.7 times. Average yield of

paddy cultivation has increased from 806 kg/ha to 3588 kg/ha where as wheat crop average

yield has increased from 958 kg/ha to 4925 kg/ha over the period of last 50 years. Thus, it has

given further stress on ground water.

4.5 Hydrogeology

The district is occupied by geological formations of Quaternary age comprising of Recent

alluvial deposits belong to the vast Indus alluvial plains. Central Ground Water Board has

drilled one exploratory borehole and 15 piezometers to delineate and determine potential

aquifer zones, evaluation of aquifer characteristics etc.

Ground water exploration undertaken by CGWB has revealed the presence of 4 sets of

aquifer groups down to a depth of 312 m. These zones


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4.6 Water level behavior

43

Depth to water level in the area ranges from 6.0 to 29.0 m bgl during pre-monsoon period and

is shallow in northern part and deeper in southern part. Deepest water levels are normally

reported from parts of Shahkot block.


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In major part of the district water level varies between 10 and 15m. Long-term net change of

water levels indicates a general decline (negative change) in the large part of the district and

it is up to 8.18m. The maximum fall is observed in parts of Nakodar and Shahkot blocks.

4.7 Ground water flow

Elevation of the water table in the district varies from 205m to 240m above msea level.

Average gradient of the water table is of the order of 1.08 m/km. Overall flow of ground

water is towards south- west direction.

4.8 Drinking water supply

Entire drinking water supply to all the rural as well as urban sectors of the district is based on

only ground water through deep tube wells drilled down to the depth of 150 m. These tube

wells tap aquifer zones from a depth range of 55 m to 143m. On an average 35m thick aquifer

is tapped for extracting Ground water.

4.9 Tube well irrigation

There are 92,734 shallow tube wells ranging in depth from 25 to 60m and provide irrigation

to 200349 ha area which constitutes about 88.09% of the total irrigated area. Discharge of

these shallow tube wells ranged between 100 and 800 lpm with a drawdown of 1.0 to 3.5m. A

large number of shallow tube wells generally exist in the blocks lying in southern parts and

deep

Tube wells exist only in Shahkot and Lohian blocks of the district. This is primarily due to

occurrence of relatively finer grained sediments in these blocks.

5.1 Designing a rainwater harvesting system

For the design of a rainwater harvesting system, rainfall data is required preferably for a

period of at least 10 years. The more reliable and specific the data is for the location, the

better the design will be. Data for a given area can be obtained at the meteorological

departments, agricultural and hydrological research centers and airports. One simple method

of determining the required storage volume, and consequently the size of the storage tank, is

shown below:


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With an estimated water consumption of 20 L/C*d, which is the commonly accepted

minimum, the water demand will be = 20 x n x 365 l/year, where n=number of people in the

household. If there are five people in the household then the annual water demand is 36,500

liters or about 3,000 l/month. For a dry period of four months, the required minimum storage

capacity would be about 12,000 litters. As rainwater supply depends on the annual rainfall,

roof surface and the runoff coefficient, the amount of rainwater that can be collected =

rainfall (mm/year) x area (m2) x runoff coefficient.

As an example: a metal sheet roof of 80 m2 with 800 mm rainfall/year will yield = 80

x800x0.8= 51,200 l/year. Demonstrates the cumulative roof runoff (m3) over a one-year

period and the cumulative water demand (m3). The greatest distance between these two lines

gives the required storage volume (m3) to minimize the loss of rainwater.

5.2 Typical domestic RWH systems

5.2.1 Storage tanks and cisterns

The water storage tank usually represents the biggest capital investment element of a

domestic RWH system. It therefore usually requires careful designto provide optimal

storage capacity while keeping the cost as low as possible. The catchment area is usually the

existing rooftop or occasionally a cleaned area of ground , as seen in the courtyard

Collection systems in China ,and guttering can often be obtained relatively cheaply, or can be

manufactured locally.

There are an almost unlimited number of options for storing water. Common vessels used for

very small-scale water storage in developing countries in clued such examples as plastic

Bowl sand buckets, jerry cans, clay or ceramic jars, cement jars, old oil drums, and empty

food Containers, etc. For storing larger quantities of water the system will usually require a

tank or a cistern. For the purpose of this document we will classify the tank as an aboveground

storage vessel and the cistern as a below-ground storage vessel. These can vary in size

from a cubic me tree or so (1000 liters) up to hundreds of cubic meters for large projects, but

typically up to a maximum of 20 or 30 cubic meters for a domestic system. The choice of


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system will depend on a number of technical and economic considerations silted below.

Space availability

Options available locally

Local traditions for water storage

Costof purchasing new tank

Costof materials and labor for construction

Materials and skills available locally

Ground conditions

Style of RWH-: the system will provide total or partial water supply One of the main

choices will be whether to use a tank or a cistern. Both tanks and cisterns have their

advantages and disadvantages.


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5.2.3 Ferro cement tanks

Above ground level, tanks are constructed with a plain or reinforced concrete base,

cylindrical walls of Ferro cement and a roof of Ferro cement, or sometimes mild steel

sheeting. The construction of Ferro cement walls is carried out by first assembling a

cylindrical mesh of chicken wire and/or fence wire reinforcement, with or without the aid of

formwork. On to this, a cement-rich mortar of 3:1 sand: cement is applied by trowel and built

up in layers of about 15 millimeters to a finished thickness of between 30 to 100 millimeters,

depending on wall height and tank diameter. Thicker walls may have two layers of mesh. The

mesh helps to control local cracking and the higher walls may call for the provision of small

diameter vertical steel reinforcing bars for bending resistance. Sometimes barbed fence wire

is wound spirally up the wall to assist with resistance to ring tension and stress distribution.

Effective curing of the mortar between the trowel ling of each layer is very important and

affects the durability of the material and its resistance to cracking. Mortar should be still

green when the next layer is placed. This means that the time gap between layers should be

between 12 and 24hours. The finished material should then be cured continuously for up to

10 days under damp hessian, or other sheeting. A ferrocement tank is easy to repair and, if the

mortar has been properly applied and cured, should provide long service as a water-retaining

structure at a fraction of the cost of a reinforced concrete structure.

5.2.4 Rock catchments

Just as the roofs of buildings can be exploited for the collection of rainwater, so can rock

outcrops be used as collecting surfaces. Indeed, if access to the catchment area by animals,

children etc, can be prevented, a protected catchment can collect water of high quality, as

long as its surfaces are well flushed and cleaned before storage takes place. A significant

proportion of Gibraltars water is obtained from sloping rock catchments on the Rock. At the

foot of the slopes, collecting channels drain into pipes which lead to tanks excavated inside

the rock. Some artificial collection surfaces have also been formed: cracks and voids in rock

surfaces have been filled in and at large, soil covered, sloping area has been covered in

corrugated mild steel sheeting supported on short piles driven into the subsoil. This is a huge

example of what may be possible on a smaller domestic or village scale. Sometimes it proves

difficult to prevent the collected water from being polluted. If so, it is sensible to use this


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water for purposes that do not require a potable water supply, such as house cleaning,

laundry, horticulture etc, and reserve for drinking water, cooking and personal hygiene the

better quality water which has been collected from a clean roof .Use can also be made of

other forms of ground catchment where, although the collection coefficient can be as low as

30%, useful volumes of water can be collected and used for agriculture and animals.

5.2.5 Cultural acceptability

Rainwater harvesting is an accepted freshwater augmentation technology in many parts of the

world. While the bacteriological quality of rainwater collected from ground catchments is


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poor, rainwater from properly maintained rooftop catchment systems, which are equipped

with tight storage tanks and taps, is generally suitable for drinking and often meets the WHO

drinking water standards. This water is generally of higher quality than most traditional water

sources found in the developing world. Rooftop catchment of rainwater can provide good

quality water which is clean enough for drinking, as long as the rooftop is clean, impervious

and made from non-toxic materials and located away from over-hanging trees.

5.6 Maintenance

Maintenance is generally limited to the annual cleaning of the tank and regular inspection and

cleaning of gutters and down-pipes. Maintenance typically consists of the removal of dirt,

leaves and other accumulated material. Cleaning should take place annually before the start

of the major rainfall season. Filters in the inlet should be inspected every about three months.

Cracks in storage tanks can create major problems and should be repaired immediately.

5.6.1 Regulations and technical standards

The most important aspect during the construction of a rainwater harvesting system is to

completely separate the rainwater and drinking water networks. All rainwater pipe work and

tapping points should be clearly designated and secured against unauthorized use. In

Germany, the construction of a rainwater harvesting system does not require a building

approval but it is advisable to report it to the local public health office as well as the local

water supplier. Some regulations and standards should be taken into consideration during

construction and maintenance of a rainwater harvesting system


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(Graphical methode of determine the required storage volume for a rain water)5.6.2 Types of rainwater use

Rainwater systems can be classified according to their reliability, yielding four types of user

regimes:

Occasional - water is stored for only a few days in a small container. This is suitable

when there is a uniform rainfall pattern with very few days without rain and when a

reliable alternative water source is available.

Intermittent - in situations with one long rainy season when all water demands are

met by rainwater. During the dry season, water is collected from other sources.

Partial - rainwater is used throughout the year but the 'harvest' is not sufficient for all

domestic demands. For example, rainwater is used for drinking and cooking, while

for other domestic uses (e.g. bathing and laundry) water from other sources is used.

Full - for the whole year, all water for all domestic purposes comes from rainwater. In


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5.8 Disadvantages

The main disadvantages of rainwater harvesting technologies are the limited supply and

uncertainty of rainfall. Rainwater is not a reliable water source in times of dry periods or

prolonged drought. Other disadvantages include:

Low storage capacity which will limit rainwater harvesting, whereas, increasing the

storage capacity will add to the construction and operating costs making the

technology less economically feasible

Possible contamination of the rainwater with animal wastes and organic matter which

may result in health risks if rainwater is not treated prior to consumption as a drinking

water source

Leakage from cisterns can cause the deterioration of load-bearing slopes

Cisterns and storage tanks can be unsafe for small children if proper access protection

is not provided.


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5.9 Effectiveness of technology

The feasibility of rainwater harvesting in a particular locality is highly dependent on the

amount and intensity of rainfall. As rainfall is usually unevenly distributed throughout the

year, rainwater harvesting can usually only serve as a supplementary source of household

water. The viability of rainwater harvesting systems is also a function of the quantity and

quality of water available from other sources, household size, per capita water requirementsand available budget. Accounts of serious illness linked to rainwater supplies are few,

suggesting that rainwater harvesting technologies are effective sources of water supply. It

would appear that the potential for slight contamination of roof runoff from occasional bird

droppings does not represent a major health risk. Nevertheless, placing taps at about 10 cm

above the base of the rainwater storage tanks allows any debris entering the tank to settle on


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the bottom, where it will not affect the quality of the stored water, provided it remains

undisturbed.

Finally, effective water harvesting schemes require community participation which is

Enhanced by:

sensitivity to peoples needs

indigenous knowledge and local expertise

full participation and consideration of gender issues,

Taking consideration of prevailing farming systems as well as national policies and

community by low


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Conclusions

The cheap but invaluable natural resource of water in the way of floods have to be effectively stored, to

ensure safety of the people besides more importantly its effective utility for alround development

Rainwater harvesting

With the ever increasing concrete jungles besides metalling of ever increasing road metalling,

Rainwater harvesting is the ultimate method of ensuring ground water table for the benefit of all living

beings on this earth besides its flora and fauna.


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Bibliography:

Nissen-Petersen E(2007) Water from roofs,Danida

Gould G, Nissen-Petersen E(1999) Rainwater catchment systems,IT

Publications, London

Pacey A, Cullis A(1986) Rainwater harvesting: The collection of rainfall

and run-off in rural areas, IT Publications, London

https://www.rain water harvesting

https://www.Rain water harvesting & overview,


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planning & designining rain water harvesting syst

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