L-2INTRODUCTION TO WATER SUPPLY

ENGINEERING

Environmental Engineering-I

- By Prof S S Jahagirdar

CONTENTS

Sources of water, elements of water supply schemes, design period

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Raw Water Source

The various sources of water can be classified into two categories:

Surface sources, such as Ponds and lakes;

Streams and rivers;

Storage reservoirs; and

Oceans, generally not used for water supplies, at present.

Sub-surface sources or underground sources, such as Springs;

Infiltration wells ; and

Wells and Tube-wells.

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Another way to classify the water sources

Rainwater, oceans, rivers, lakes, streams, ponds and springs are natural sources of water.

Dams, wells, tube wells, hand-pumps, canals, etc, are man-made sources of water.

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DO YOU KNOW?N

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HOW MUCH WATER IS USABLE?N

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One in five people do not have access to safe drinking water

Every 15 seconds a child dies from water related diseases

Some young children and women trek up to six miles a day in order to collect water for their families

Women carrying water drums

WORLD WATER CRISIS

•Much of the world's drinking water is contaminated and poses serious health threats

WATER RELATED DISEASES AND THEIR

CAUSES

Bacteria• E. coli• Salmonella typhi• Shigella spp.• Yersiniaenterocolitica

Viruses

• Hepatitis A/E virus

• Adenovirus• Enterovirus• Rotavirus

E. coli bacteria Hepatitis A Virus

Diseases• Diarrhea• Arsenicosis• Schistosomiasis• Intestinal

Worms• Hepatitis• Cholera• Malaria• Trachoma• Typhoid• Fluorosis

Problems with High-Tech Treatment Systems for Rural Areas of Developing Countries

• Usually are expensive and difficult to construct• Require expensive mechanical equipment• Require expensiveand dangerous chemicals (e.g. chlorine- carcinogenous)

High-Tech treatment system

A CURE FOR THIS GLOBAL PROBLEM?

OBJECTIVES OF WATER TREATMENT

1. To remove colour, dissolved gases and objectionable colour of water

2. To remove objectionable taste and odour.

3. To remove disease producing micro-organisms so that water is safe for drinking purpose.

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4. To remove hardness of water (In case of ground water source).

5. To make it suitable for wide variety of industrial purposes such as steam generation, dyeing etc.

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USES OF WATER

i. Drinking, cooking and washing

ii. Bathing

iii. Swimming pools and water games

iv. Fountains and cascades (Display)

v. Watering of lawns and gardens

vi. Air coolers and dish washers

vii. For fire fighting

viii. Industrial operations such as steam generation

ix. Irrigation

x. Sanitary purposes

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ELEMENTS OF WATER SUPPLY SCHEME

1. Selection of source – River, lake or open ,

tube well

2. Collection and conveyance of raw water – Intake works, pump house, rising main etc

3. Treatment of water- Multi barrier

treatment to remove different types of impurities and pathogens

4. Pumping and storing the treated water in the E S R s

5. Distribution- network of pipes is needed

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DATA TO BE COLLECTED FOR DESIGN OF WATER

SUPPLY SCHEME

1. Sources of raw water – Choice amongst

alternatives, reliability throughout the year

2. Quantity of water required which depends upon

- Population to be served- Population

forecasting, census data

- Water demands- domestic, public, industrial,

fire etc

- Design period – 30 yrs is common

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3. Quality of water – analysis of

water, line of treatment is decided by raw water quality

4. Survey data – Topographical

maps

5. Plan or map of city or town-for knowledge of existing structures and roads etc

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FACTORS AFFECTING DESIGN PERIOD

1. Useful life of the components of water supply scheme (Pumps, intake structures, rising main, pipe distribution network etc.) will decide the design period.

2. Higher design period has to be adopted if there are difficulties in future expansion.

3. Availability of funds. Less funds less design period

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4. Rate of interest on the loans. Larger the rate of interest smaller is the design period and vise-versa.

5. Rate of increase in population is lower then higher design period is adopted.

6. Quantity of water available. If required quantity of the water is not available for longer periods then lesser design period shall be adopted

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DESIGN PERIODS FOR COMPONENTS OF WATER

SUPPLY SCHEME

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OBJECTIVE QUESTIONS

1. The fresh water content on the earth is ______%.

2. Safe water can be obtained by using advanced __________________.

3. Much of the world's drinking water is ______________ and poses serious health threats

4. Design period for pumps is ____ years.

5. Purpose of water treatment is _______________

(to remove odour/to remove taste/to kill pathogens/ all of above)

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THEORY QUESTIONS

1. Discuss classification of sources of water in detail.

2. Explain elements of water supply scheme

3. Discuss objectives of water treatment.

4. Write short notes on

i. Factors affecting Design Period

ii. Data to be collected for design of water supply scheme

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NEXT LECTURE

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